Weak knowledge of building control: March 2011

Sunday, March 27, 2011

Weak current College】【warm temperature control mode.

1. overall temperature: If the room is relatively small, most appropriate overall temperature control. Overall temperature is the temperature control system installed in the diversity of water in front of the main line, use it to control the temperature of the heating room.

2, room temperature: room temperature fit room more building, because in many cases some of the rooms is idle, and room temperature to achieve energy-saving effect. Individual room control is passed to each room temperature controller, control of the water in the diversity of the actuator, adjustable flow for each branch, to control the room temperature.

3, regional control: some of the larger room, a single loop is unable to complete the heating requirements, take several loop of pavement can guarantee the indoor temperature required, also some room for room temperature requirements almost the same, only the individual room on room-temperature requirements are different, so that we can adopt the regional temperature control system. Zone control is similar to the room temperature requirements, comfort request high main room installation temperature controller, and then set the thermostat water with the diversity of multiple electric actuator, using a thermostat temperature control in a zone.

4, tiered lab control: tiered lab temperature is mainly used in Villa heating system, Villa building larger, more room, layered and room temperature of installation is extremely important. Tiered room temperature is at every layer of water connecting diversity in charge of road, install the controller on the precise control of the temperature of each layer. You can adjust the diversity of water on the manual control valve to control each room of the indoor temperature. If you want to reach room temperature for precise control, you can set the thermostat in each room, as realization of individual room temperature control.

【 Weak current College 】 inverter issues on

With the universal converter market's growing prosperity, not including OEM import converter, converter, exceed 25 million Yuan, the converter and its ancillary equipment installation, commissioning, maintenance and repair of the workload that give users a significant direct and indirect losses. This article will address the reasons for the above problems, according to the practical application of a large number of users, from the application environment, electromagnetic interference and anti-interference, power quality, electrical insulation, and other aspects of the analysis, made some suggestions for improvement.

2 working environment issues

In the converter in the practical application, since domestic customers in addition to a few private rooms, most of them in order to reduce costs, the inverter installed directly in the industrial field. The work site in General is dust, temperature, the humidity in the South there is a big problem. For the cable industry and metal dust, ceramics, textile and other industries have corrosive gas and dust, in mine, etc, explosion-proof requirements, etc. It must, in accordance with the situation to make the appropriate countermeasures.

2.1 inverter installation design basic requirements

(1) the converter should be installed in a control cabinet.
(2) it is best to install the converter in the control cabinet within the Central; frequency changer to vertically installed, just above and below to avoid the installation may stop the exhaust, intake of large components.
(3) on the bottom edge of converter, distance control cabinet top, bottom, or divisions, or large components must be installed, and so the minimum spacing should be greater than 300mm.
Cabinet installation inverter basic requirements
(4) if the special users in use need to remove the keyboard, the keyboard, pore converter Panel, be sure to use the tape seal or use fake strictly Panel replacement to prevent large amountsof dust into the inverter.
(5) the inverter to be undergoing scheduled maintenance, timely cleaning dust inside.
(6) other basic installation and usage requirements must comply with the user manual for instructions; if you have questions please contact the appropriate manufacturer's technical support staff.

2.2 dust control cabinet design requirements

In many places, especially the dust than metal dust, flocks of establishments using inverter, take proper and reasonable protection measures are necessary, appropriate dust control measures to ensure the inverter function is very important. General requirements for the control cabinet as a whole should be sealed, through specially designed inlet, outlet for ventilation; control cabinet top should have the safety net and protective roof outlet; control cabinet bottom should have a floor and air inlet, entry hole and install dustproof mesh.

(1) control cabinet of duct to design reasonable, exhaust patency, avoid cabinet form vortex in a fixed location, in the form of dust buildup.
(2) control cabinet above the top outlet to install protective cover to prevent debris directly into the hands of the top cover height; protective to reasonable, does not affect the exhaust. Protective cover side outlet to install protective NET, prevent debris directly into the hands of flocks.
(3) if the use control cabinet top side exhaust, outlet must have a safety net.
(4) it is important to ensure that control cabinet top of axial-flow fan rotate in the right direction, to exhaust. If the fan installed in the control cabinet top external, you must ensure that protective cover and fan are sufficient height; if the fan installed on the top of the internal control cabinet, install the screws must use only top-shells, prevent loss caused in the Cabinet fan components and equipment damage. Recommended for fans and retrofitting plastic between the Cabinet or rubber damper washer, can significantly reduce fannoise and vibration.
(5) the control cabinet's front and back doors and other joints, you want to use gasket or sealant to seal the deal, will prevent dust to enter.
(6) control cabinet bottom, side panel of all the air inlet, entry hole, dust-proof network installed. Blocking of flocks sundries. Dust networks should be designed to be removable for easy cleaning and maintenance. Dustproof mesh grid to small, can effectively block the small flocks of (and general household anti mosquito screens similar to the grid); or a case-by-case basis to determine the appropriate size of the grid. Dust networks around and control cabinet in combination with the Department to work with closely.
(7) on the control cabinet must carry out regular maintenance, timely clean internal, external, flocculation of dust, hair and other debris. Maintenance cycle may, under specific circumstances, but should be less than 2 to 3 months; a place for serious dust, recommended maintenance cycle in about 1 month.

Dust control cabinet installation requirements

2.3 7、it mildew control cabinet design requirements

Most of the inverter manufacturers internal PCB, metal structures are not anti-wet moldy special processing, if the inverter long in this State, the metal structure is prone to corrosion, conductive copper in high-temperature operation, compounded by the corrosion process. For computer control board and driving power plate of fine copper wire, as a result of corrosion will be damaged, therefore, apply to damp and and contain corrosive gases, must use the inverter's internal design with basic requirements, such as printed circuit board must adopt three prevention paint spraying, for structural components must be in the process of Nickel-chromium-plating, etc. In addition, you also need to adopt other positive, effective and reasonable protection against moisture, corrosion gas measures.

(1) control cabinet can be installed on a separate, sealed rooms withair conditioning, this method if the control device, the cost of establishing the engine room below the showcase separate confined disposal occasions, at which point the control cabinet can be used as a dust or general environmental design.
(2) separate inlet. Separate inlet can be located at the bottom of the control cabinet, through independent confined trench and external clean environment connection, this method will need to install an air intake Department, dust-proof network if ditch less than 5 m and above, you can consider adding blower.
(3) Within the closed control cabinet can be equipped with desiccant moisture absorption or adsorption of toxic gases of active materials and recently replaced.

3 interference problems

3.1 inverter on the interference of microprocessor-based control panel

In the injection moulding machines, elevators, etc., control systems, the use of computer or PLC control, system design or renovation process, be sure to note the converter to computer control board interference problems. Because the user's own design of microprocessor-based control panels generally poor level of technology, does not comply with the EMC international standards, inverter, produced by conduction and radiation interference, often resulting in control systems are not working properly, and therefore need to take the necessary measures.

(1) good grounding. Motor control system such as strong electric should grounded through reliable earthing grounding bus, microcomputer control plate shield, it is best to separate earthing. For some jamming serious occasions, it is recommended to place sensors, I/O interface screen and control panel is connected to the control of land. [3]

(2) to the computer control panel input power retro EMI-filter, common mode inductors, high frequency magnetic ring, low cost. Can inhibit conducted interference. In addition to radiation interference serious occasions, such as GSM, around exists or PHS stations, you can add to the microcomputer control sheet metal mesh shielding enclosures for shielding.
Microprocessor-based control panel power anti-jamming measure

(3) to enter the frequency converter with EMI filter, can inhibit the inverter to the power grid, conduction interference with input AC and DC reactor L1, L2, improves the power factor, reduce pollution, the combined effect of harmonics. In some distance between the motor and frequency inverter over 100m occasions, you will need to add the inverter side AC output reactors L3, resolved because the output wire-to-ground distribution parameters caused by leakage current protection and reduce external radiation interference. A proven method is to use pipe threading or shielded cable, and the steel shell or cable shield and reliable connection to the Earth. Please note that without adding AC output reactors L3, with pipe thread or shielded cables of methods to increase the output to ground of distributed capacitance, prone to over-current. Of course, in practice generally only take one or several methods.

Reduce the frequency of external control device of interference

(4) on analog sensors detect input and analog control signal electrical shielding and isolation. The inverter control system consisting of the design process, we recommend that you try not to use analog control, in particular control distance greater than 1M, cross-control cabinet installation. Because converters generally have more •8, switching frequency input output, you can meet the requirements. If you want to use the analog control, it is recommended that must use shielded cables and sensor side or inverter side to achieve remote grounding. If the interference is still seriously, you need to implement the DC/DC isolation measures. You can use standard DC/DC module or use V/F conversion, use frequency isolated Lotus set input method.

3.2 inverter itself anti-jamming problems

When the inverter power supply system in the vicinity, there are high-frequency impulse load such as welder, electroplating, electrolysis power source power supply or use of slip ring power supply, inverter itself easily because of interference protection. It is recommended that the user uses the following measures:

(1) in the frequency converter input side added inductance and capacitance, constitute an LC filter network.
(2) inverter power cable directly from a transformer side power supply.
(3) the conditions permitting, you can use a separate transformer.
(4) the use of external switch quantity control Terminal control, the connection line is long, it is recommended to use shielded cables. When the control line and main circuit power are laid in the trench, in addition to the control line must use shielded cables, the main circuit line must be steel shield for threading, decrease mutual interference to prevent incorrect operation of the inverter.
(5) the use of external analog control Terminal control, if the connection line 1 m or less, the use of shielded cables connected, and implements inverter side grounding it; if the line is long, spot jamming serious occasions, it is recommended that you install the inverter DC/side DC isolation module or use a V/F conversion, using frequency directives control the given mode.
(6) the use of external communication control Terminal control, recommended STP and inverter side of shield earthing (PE), if the interference is very serious, it is recommended that the shielding to receipt control power (GND). For RS232 communication method, note the control line try not to exceed 15m, if you want to lengthen, must reduce the communication baud rate, to around 100m normal communication baud rate is less than 600bps. For RS485 communication, you must also consider the terminal match resistance, etc. For field bus speed control systems, communication cable must be used for the cable and adopt more grounded way in order to improve reliability.

4 power quality issues

In the high-frequency impulse load such as welder, electroplating, electrolysis power, power supply, voltage often flicker; in a workshop, there are hundreds of inverter normovolemic rectifying load as you work, power system harmonics is very large, for power quality has a serious pollution, on the device itself also has considerable damage, the light is not capable of continuous uptime, the resulting device input circuit damage. You can take the following measures:

Centralized rectification DC total bus power supply

(1) in the high-frequency impulse load such as welder, electroplating, electrolysis power source power supply, etc it is recommended that the user adds the static var compensator, increase the power and quality.
(2) in the frequency converter comparison set workshop, it is recommended that the centralized rectification, the DC bus power supply in total. We recommend that users use 12 pulse rectifier mode. The advantage is that the harmonic minor, sectionCan, especially suitable for frequent play brake, electric power to run and run simultaneously.
(3) converter input side with passive LC filter, decrease the input harmonic, improve power factor, low cost, high reliability and good effect.
(4) and is equipped with a frequency converter input side PFC devices work best, but the costs are relatively high.

5 motor shaft voltage of leakage, and bearing currents issues

Inverter-driven motor, motor models and Csf for stator casing between equivalent capacitance, stator and rotor Csr as the equivalent capacitance between the Crf for rotor and equivalent capacitance between the enclosure, Rb-bearing on the shaft of the electric resistance; Cb and Zb-bearing oil film capacitor and non-linear impedance.

High-frequency PWM pulse input, motor voltage within distributed capacitance coupling effect constitute a system of common-mode loop, thus giving rise to the leakage current, voltage and current of the bearing axis.

Inverter-driven motor models of induction motor

Leakage current is PWM voltage three-phase power supply is very transient voltage unbalance between the Csf and the Earth. Its size and PWM DV/dt size relative to the size of the switching frequency, its direct result will lead to a leakage protection device action. In addition, for legacy machines, because of its poor insulation materials, and after a long run of aging, some after frequency conversion of the insulation damage. Therefore, we recommend that before upgrading, you must test for insulation. For the new variable-frequency motor insulation, requirements than a standard motor with high a level.

Bearing current major presence in three ways: dv/dt current, EDM (ElectricDischargeMachining)-current and current loop. The size of the axis voltage not only with the motor parts within the parameters of the coupling capacitor and pulse voltage rise time and amplitude. Dv/dt current major and PWM rise time tr, tr, dv/dt current amplitude increases; the higher the carrier frequency inverters, bearing currents of dv/dt-current components. EDM current certain contingency occurs only when the bearing with grease layer breakdown or bearing internal exposure, stored in the electronic rotor Earth capacitor charge of Crf (1/2Crf×Urf) through the bearing equivalent circuit of Rb, Cb and Zb on and spark discharges causing decrease, reduce the bearing finish life, serious damage caused directly. The extent of the damage depends primarily on the axis voltage and stored in the e-Crf rotor Earth capacitor size.

Loop current in power transformer grounding wire, wire, electrical ground the inverter and motor load and earth ground between loop (such as water pump load). Loop current main cause conducted interference and ground jamming, inverter and motor. Avoid or reduce the circulation is to minimize the impedance of the ground loop. Because of the frequency converter grounding wire (PE inverter) General and electrical grounding wire (PE motor 1) connected to a point, therefore, must as far as possible, bold motor grounding cable diameter, decrease the resistance between the two, inverter and the power of the Earth with ground wire copper bus or dedicated grounding cable, to ensure good grounding. For diving deep-well pump this load, ZE motor 2 grounding impedance may be less than ZE transformer and ZE converter, easy formation and circulation, it is recommended to disconnect the ZE inverter, anti-jamming performance better.

The inverter output strings consisting of inductance, RC sine wave filter is suppressing shaft voltage and an effective way of bearing currents. There are a number of manufacturers to provide a standard filter.

6 closing

This article from the converter to the practical application of system problems, from application environment, electromagnetic compatibility and power quality, electrical insulation, etc, to put forward some solutions to problems and suggestions for improvement, for inverter in the practical application of a reference value.

【 Weak current College 】 water flow sensor principles and applications-Power By 【 China power house network 】

A basic principle of the flow sensor is the use of the Hall element of Hall effect to measure the magnetic physical quantity. In the Hall elements of cathode conspiracy into load resistance, at the same time pass on 5V DC voltage and current direction and magnetic field direction orthogonal. When the water through the turbo switch magnetic rotor spinning shell advance, produce different poles of the rotating magnetic field, the magnetic wire cutting, high and low pulse level. Because of the Hall element of the output pulse signal frequency and magnetic rotor speed proportional to the rotor speed and flow proportional to the size of the under water heater starts. The pulse signal frequency experience formula see-(1).
f=8．1q-3 (1)
Type: f-pulse signal frequency, H2
Q-flow, L/min
The water flow sensor feedback signal through the controller to determine the value of the water flow. According to the different gas heater model, choose the best boot volume, you can achieve ultra low voltage (0.02MPa) started. 2 works water flow sensor is mainly composed of copper valve, flow rotor components, steady flow component and Hall components (see Figure 1). It is mounted on the inlet side of the water heater is used to measure water flow. When water flows over the rotor component, magnetic rotor rotation and speed change linearly with the flow. Hall element output the appropriate pulse signal back to the controller, the controller determines the size of the water, adjust control proportional valve's current to adopt proportional valve control gas volume, avoid the use of gas water heaters in summer and warm winter during cool phenomenon. Water flow sensor fundamentally solves pressure differential pressure of the water-oil valve starts and tipping water valve is easy to miss the action appears dry heating and shortcomings. It has a reflecting sensitive, long life, fast action, safety and reliability, connect the flow to facilitate launch ultra low (1.5 L/min), etc., by the majority of users.
Figure 1 flow sensor flow rotor components mainly by turbine switch shell, magnetic rotor, brake ring. Use the current switch modes, its performance advantages over mechanical pressure differential disk structure and size significantly narrowed. When the water flow through the turbine driven magnetic switch shell, rotor rotation, different pole near the Hall element, a Hall element on-time departure hall element is disconnected. From here, you can measure out the rotor speed. According to the measurement of water flow and rotor speed and output signals (voltage) of the curve, you can determine the start of the water heater, water pressure and start pressure corresponds to the start of the water and the rotor speed start. The control circuit, we can achieve when the rotor speed is greater than the start when you start the work speed; the water heater at speed is less than start speed, water heaters and stop working. This water heater starts pressure MPa in the General settings, start the water flow 0.01 for 3 ~ 5 L/min (required to meet the water heater standard on maximum temperature rise limitation). In addition, because the water in the magnet magnetic cutting, become magnetized water, the oxygen content in the water increases, so people feel refreshed after bathing. Brake ring is shut off, the Suppression of high-speed rotating magnetic rotor rotation, termination of pulse signal output. Controller not receive pulse signal, immediately control combustion proportional valve closing valve, cut off the gas to prevent ganshao. Three water flow sensor and comparison of air-oil valve pressure-water and oil valve disadvantage is the high water pressure startup, and to reduce water pressure need to sacrifice some steady flow characteristics (flow-pressure fluctuations of stable capacity). In order to be able to make both, only intensify the water valve diaphragm, such as the body increases costs will rise, and the flow starting pressure indicators cannot go too low. On the water flow sensors, in the water-side to increase stability, steady flow components. Ring of geometry and physical performance, through the test successfully developed apply to different capacity water heaters of steady flow components, has good stability characteristics (inlet pressure variation in 0.1 ~ 0.5MPa, yield change in 3L/min), ensure that the water pressure variation, maintain flow in a certain range, reached the thermostatic effect.
Compare pressure-water and oil valve and flow sensors, can be seen, the former is a more complicated mechanical, structural, small and great, but the control circuit is simple; the latter is electrical, relatively simple structure, small size, but the control circuit of the complex. More important is the former high water pressure startup, waterway system resistance, it is not advisable to use larger in 10L/min or more bulk water heater AZ; while the latter started water down the waterway system resistance is small, in more than 10L/min bulk water heater has been widely used. IV conclusion in recent years, the use of water flow sensor measuring flow in strong type Digital thermostat heater in a large number of applications as it turns out, uses water flow sensor has a simple structure, high reliability, a wide range of measurement, etc. If you can match the combustion proportional valve for gas ratio adjustment, can achieve gas water heater in the combustion process of automatic control.

【 Weak current College 】 air-conditioning refrigerant recovery equipment of four functions---Power By 【 China power house network 】

1. recycling: recycling process is the air conditioning system refrigerant to refrigerant tank. Due to the pressure of the refrigerant tank is roughly equal to the pressure of the air conditioning system (i.e., refrigerants condensing pressure), so called device has a booster function, this function implementations rely mainly on the compressor. Our products are used by the compressor is no oil-so that the device not only has a booster function, and can be used as a hydraulic pump. Recovery speed is improved, and can be gaseous, liquid and recycling.

2. regeneration: the regeneration process is recycled back to the process of handling refrigerant. Recycling of refrigerant in mainly solid particles, refrigeration oil, water, air, and several major categories. This task consists of drying filter. It can remove the recovered refrigerants and solid impurities in the water, not oil separator inside the device, you can isolate the recycling of refrigerant in the refrigeration oil. Because air belongs to the Non-Condensable Gas. After the end of the collection can be adjusted by the refrigerant tank drain valve on the discharge of air in the tank, the regeneration process guarantees the recovery of the refrigerant can again be used.

3. vacuum process: as the recycling of air conditioning system does not meet the requirements of the vacuum, so it must be on the air conditioning system thoroughly vacuum. This also helps to remove residual moisture in the system and other gases. Ensure that the filling into the system again the refrigerant is not pollution, this process consists of devices equipped with bulk imports two-stage vacuum pump, to finish, taking the more thorough, and help to detect air conditioning system of tiny leaks.

4. Add: air conditioning systems after maintenance needs to inject the refrigerant in the system, for small air conditioner, rely primarily on refrigerant tank and is sucked out of the system pressure before in the refrigerant into the system. For large air conditioning, this company to recycle charging machine design pressure filling function, the device's internal implementation of refrigerant compressor to transfer in the system. Rely on accurate electronic measurement system for automated quantitative charging refrigerant.

【 Weak current College 】 enterprise video conferencing system's three top technical---Power By 【 China power house network 】

According to the market advisory company WinterGreenResearch forecast, the unified communications market development cycle is about to step into the healthy growth and rapid application of the stage. In 2008, the market may achieve 15% growth in 2009 will grow .by 30%. And video in the enterprise-class unified communications deployments will be uncompromising black horse. Traditional enterprise video technologies include: MCU, H.323, frame relay, and IP network-based video application, would bring more rich .functionality to the user. But to successfully use these features, the user needs to some new hot technology to give more attention. A LPR: get stable video stream Unified communications enterprise voice, video .and data synchronization hosting over IP networks to transfer the video data packets, which inevitably encounter network packet question. Packet loss will result in video image mosaic; image local deformation, frequent refresh or flashing screen; video and audio are not synchronized; frame rate drops .and the still image. In unified communications, video, voice and data flow is synchronous transmission, packet loss will result in overall audio distortion, continuous or intermittent noise, as well as the quality of the content of the presentation, such as fuzzy distortion of .slide or page slower, etc. These issues will significantly impact the consumer experience of application. If the network packet loss rate is too large or too frequently, will cause the excessive delay for video communication, or even result in loss of communication. Packet loss is congestion by internal or external network priority flow caused by the conflict, etc. To avoid loss, it is first necessary to determine the host network packet loss rate, packet loss distribution over time, as well as a video .call in various terminals and equipment performance. LPR (packet loss recovery) is the current resolution of video transmission packet loss of one of the most effective method, the technology is based on Polycom company developed a new algorithm, with .the aim of protecting IP video call from the effects of network packet. In fact, LPR is a use of forward error correction (FEC) method to override the implementation of lost packets. By the sending system to issue a data stream to add redundant data .so that the receiving system can detect and correct the error without having to request the sending system to transfer the missing information. This is not required to wait for the network will have the ability to correct, make the FEC is ideal for real-time communications ., such as television broadcasting, IP telephony and IP video conferencing. LPR works through video Terminal control all ongoing calls inbound packet information. Once detected, packet loss, the terminal will take three means to guarantee call quality: lost .packet recovery (LPR), the dynamic bandwidth allocation (DBA), and does not support LPR, using the traditional video error yinxiao (PVEC) technology. Unlike most mistakes avoidance algorithm only yinxiao or intervene in receiving packet loss .information system, LPR will intervene to video call in all levels of the system, part by temporarily assigned to a call bandwidth data channel, which is used to send FEC data to the receiving system to play a role. In the network packet loss occurs, .a loop through the above process, LPR will increase or decrease the size of the FEC data channel until you find must be assigned to the FEC data channel minimum bandwidth, allowing the receiving system to be able to recover all lost packets. < .br> When the FEC data channel is larger than the standard value, the system will detect whether you can reduce over FEC data channel size for audio, video and content data provide more bandwidth available on the phone. Since LPR only detect packet loss will only .be occupied bandwidth, this feature makes the LPR is great for random or unexpected packet environment. Against packet loss rate relatively fixed network environment, the dynamic bandwidth allocation (DBA) function in conjunction with LPR. DBA is also a .kind of algorithm, you can video call process automatically and dynamically adjust the video bitrate, to eliminate or avoid packet loss. For example, in a video call 384kbps detected a stable at 10 percent packet loss rate, the DBA will decrease by about 10% .of the video bit rate to minimize by 320kbps 288kbps left and right, and resampling signals, to see if there are packet loss. If necessary, the DBA can further reduce the video bit rate, until a few seconds until it no longer appears lost packets .. At lower bit rates, if measurement of packet loss for the DBA temporary phenomenon, the DBA will gradually increase the video bit-rate. Conversely, if the DBA continues to detect packet loss, it will no longer resize .video bit rate, but will continue the call. Therefore DBA applies to Internet overuse or throughput problems caused by packet loss environment. The parties involved in communication systems do not support LPR, you can use video error yinxiao (PVEC .) feature. PVEC is an IP video quality of service (QoS) algorithm, it can by packet loss effects caused by the compensation. It is through the use of neighboring macroblock, front frame and the rear frame to estimate the current contents of the video .frame. And LPR recover lost packets and DBA avoid packet technology, the role of the obscure PVEC packet loss. On this basis, the LPR that users can BER higher IP networks (DSL, cable, satellite, high conflict .and LAN / WAN, etc) for high quality video calls without having to endure the consequences of lost packets. Through the ongoing call rate for temporary adjustment, LPR can protect a video call from short-time network problems. Once the network problem solving, .LPR will initiate the call rate or current bandwidth availability, automatic bit rate back to the highest level. This makes network bandwidth can be fully utilized to achieve the recovery of lost packets and transmission of real-time reconstruction so that the audio and video data stream .patency, exclude waiting, intermittent, noise or information clutter, more capable of reducing the dynamic jitter buffer emptyAnd related delay. But using LPR generates FEC channel bandwidth, the use of the video call itself reduce the available bandwidth. .In the low connection speeds, can cause temporary reduced frame rate or resolution. The second restore site: face-to-face experience Users for video image is clear, the real requirement is that .there is no upper limit, which directly led to Cisco, Nortel Networks really really far and the birth of the HP Halo to these products as representative, the application will take advantage of enterprise video-high definition technology, the experience of implementing reduction field. . Unlike traditional video conference system, the most obvious of these products is characterized by its ultra-high-definition resolution. According to reports, the network's system uses three high-definition plasma display, each screen resolution can achieve 1080 .× 1080p, than the existing international standards in HD resolution (1280 × 720p) twice, is an ordinary TV resolution 10 times. Provides 6 people at the "virtual meeting" of the network's 3000, each plasma screen required bandwidth in 2 ~ 3 screen .between 4Mbps, total needs around 10Mbps bandwidth, ordinary ADSL is not possible to host, so the need for specialized dedicated line access or fiber access. Ultra high performance capabilities of the image with high-fidelity audio, as well as ergonomic environment design, the .Cisco network's performance in meeting system to real exchange in every detail, such as "clear the whites, the hairs on the skin, as well as the communication between each other slightly shy look", etc. It is understood that the net prices actually is .7.9 ~ 29.9 million in AMD, Pepsi, GE and other large enterprises. HP's Halo Studio system emphasizes that can be used for corporate remote simulation face-to-face business meeting. Connect through Halo Halo Studio, each can .support the Conference table in front of six persons, the second row of three to six persons, up to 12 people in the meeting size. Each Studio have three plasma display, participants can see and I the same size of the image. In addition, .attendees can also use an installation in the plasma display above the 50-inch screen, in collaboration with other Halo Studio staff share their notebook computer files and data. Studio also includes a high-definition picture and video camera, can be used for filming the .items on the table and displayed in collaboration on a monitor, real render color, shadow and subtlety. At the same time equipped with phone let attendees can work outdoors and Halo. Studio equipped with broadcast-quality audio and lighting facilities, the participants can use .the screen and easy user interface, start by clicking on the mouse. A complex software control system will ensure that Halo Studio easily and seamlessly work together. HP Halo adopts high-bandwidth, separate connection of specialized video switching network .provides full-motion video HVEN experience, which makes global Halo Studio audio or video delay will not be people perception. In order to ensure a 24 × 7, HP provides include: network operation and management, remote diagnostics and troubleshooting, security protection, equipment .maintenance and subsequent maintenance and repair services. Users do not need to manage Halo Studio operation and maintenance, Currently, HP has 18 countries worldwide and has over 60 such Studio. According to reports, .the HP Halo collaboration Studio package for the price of the room is 39.9 million dollars, plus monthly 2.4 million ~ 2.5 million in service fees. At present, the user already includes Halo dream factory, Novartis, AIG financial products, BHP Billiton (BHP Billiton .), Canon, and other well-known companies. Nortel's ultimate far really (Telepresence) system is fully embodied communication "rendering", life-size screen, HD seamless video effects and StereoSurround sound effects, collaborative multimedia content .to show, video multipoint control technology (MCU) recording, archiving, streaming media and high-definition support services. More optimization is that this kind of experience you can demand from two small meetings, to be able to accommodate up to 28 people large meeting .room, users can realize high-definition video communication and at the same time seamlessly show film, data tables and other collaborative format the content of the document, is equivalent to a complete virtual people in the Conference room is able to complete all activities. The .entire process is based entirely on offsite meeting environment of far from true. Extreme far really system characterized by modular features; Studio-grade lighting; professional acoustic treatment; no remote control and control of man-machine interaction; hidden .-camera, microphone and PA system. Each element is designed to integrate fully reflects the technology of seamless and transparent as well as the organic integration of the physical environment, forming a unified environment for audio and video conferences. In addition you cannot shake hands, .and face-to-face meetings have no difference. Nortel is really a standard turnkey, Nortel offers a comprehensive set of services. Including the scene investigation, network assessment, project management, open services, 7 × 24 - .hour support, and is designed for high-definition system MNOC multimedia services, 24 x 7 meeting booking, proactive remote monitoring, Conference building, confirmation and reporting of monthly remote services. Three QoS: high-quality transmission security . In the network application QoS is not new technology, but in video hosting online streaming media QoS is a new hot technology. Business-to-video technology innovation is streaming media technology into the mainstream .of the application. Streaming media playback with strict requirements, the requirements of real-time at specific intervals to decode a specific data cell. Currently streaming media business in a number of issues, such as media files playback pause, mosaic phenomenon, there are a .large number of users access a top emergency content server processing difficulties, and so on, these issues are related to streaming media QoS guarantee. Enterprise video because of the mostly applied in critical business, but also with the voice, .dataSynchronous transmission, so the network transmission quality have higher requirements. Streaming media QoS needs to address two issues, bandwidth and delay jitter. We all know that video, and voice and unified communications is the most consumed bandwidth in the .network application. Bandwidth limit on the one hand, affect the quality of video playback; on the other hand, because the streaming media applications consuming bandwidth, and network with other business in the contend bandwidth on the business impact of normal operation. . In addition, IP network for video data grouping store and forward mechanism determines the latency and jitter is inevitable, therefore convective media transport, the end-to-end delay should be controlled to a certain range. Streaming media QoS with advanced video .coding schemes, in improving the efficiency of the video data compression, as far as possible eliminate redundant information in the video, making source code output for as little as possible the amount of data, thereby adapting the minimum transmission bandwidth of the network. At the .same time, you can provide flexible video quality rating to best adapt to the dynamic nature of the network, as far as possible, providing users with better video quality. Scalable coding technology increases the encoded output stream, adapted to .network bandwidth, the flexibility of dynamic change, multimedia data compression into multiple streams. One can decode, called basic Bitstream, other stream called enhanced layer. They are not individually decoded, but only with the basic layer and its previous reinforced layer combined with decoding ., used to improve viewing. .

Weak current College】【air conditioning system control table-dangerous points - Power By】【China power house network.

<thead> Job name air conditioning system serial number danger point control measures </ thead> 1 work sheet 1, work on the security measures should be perfect; 2, maintenance operation personnel to equipment onsite review safety measures; 3, the .assignee should work ban member account safety considerations. 1, 2 falling heights must be tied up, hang tight belts, seat belts in should check before use; 2, conditioners overhaul should be completed with catching device; 3, staff should not hinder heights of .disease, where there is the prohibition mental abnormality. 3 physical shock 1, wet hand strictly prohibits engaging in power; 2, electric utensils power cord and motor insulation good, non-destructive power cord and mixing with protector and nimble Cable Tray; 3, .in particularly humid and surrounding areas are the conductor should use the line with voltage safety lights; 4, power cable should be hung on the fixed part, is strictly prohibited on the rotating parts; 5, working on the electrical circuit should wear near electric alarm .. 4 of wounding 1, high job should use a tool bag, ropes hold delivery tools; 2, avoid lower level jobs, you sure can't avoid, two face should be installed the protective net of sufficient strength; 3, the prohibition on .lifting of walking; 4, staff should wear and fasten a helmet; 5, place of work should be located below the warning signs or fence or special guardianship and other preventive measures. 5 use the wheel plate, polishing machine, cutting machine 1, before .use, check the wheel plate, polishing plate fine no crack; 2, electric tool should have safety shield; 3, using wheel machine, cutting machine, staff should stand at the side of the location, do not stand in the position of the wheel .plate, and the prohibition of the use of side grinder grinds; 4, when used, should wear protective mask; 5, swap slice should disconnect power or remove the plug. 6 electric welding, flame cutting, gas welding, gouging 1, work site .should be equipped with fire-fighting equipment; 2, acetylene, oxygen cylinder distance placed as required; 1, site should no flammable substances such as alcohol, gasoline, oils, cleaning rags; 4, scene specialist care. 7 in 1 working on scaffolding ., scaffold by standard setting, experience your qualified before use; 2, scaffold erection should be firm, be able to withstand over weight people and goods; 3, scaffold use materials should meet the requirements, no insects and mechanical damage; 4, work to .prevent falling. 8 slip, fall 1, work site lighting sufficient and emergency lighting; 2, live the grease stains, sludge should be wiped clean, could not be hugely caodai or in sacks; 3, staff should wear anti-slip work shoes. .9 in 1 work on the ladder, ladders should be consistent with the safety requirements with mat; 2, when the ladder angles should be less than 60 degrees, people should stand at the distance of 1 m below the top of the ladder; 3, .ladders should be mounted securely and specialist support. 4, herringbone open device should prevent ladder; 5 and up and down the ladder should be stepped on, grab hold of. 10 use of electric tools 1, use insulated gloves for work; 2, before .checking the appearance of power tools is intact, the wires are damaged; 3, power line to be equipped with a protector. 11 fan belt replacement with the crowbar will pry into orbit belt 12 a / c charging refrigerant wear antifreeze gloves, in strict accordance .with the air conditioning maintenance regulations of operation and repair of 13 plate Tube fan 1, broken three-phase power supply; 2, note well the aerial work protection measures. 14 central air-conditioning maintenance-phase 1, disconnect the power supply; 2 ., equipment maintenance, care shall be taken to prevent electric shock and the rotating part twisted. 15 excitation room air-conditioning maintenance 1, attention to prevent electrical shock; 2, attention to prevent accidental contact excitation equipment. 16 rain valve repair and test 1 ., close the total water and rain water valve valve Access; 2, open the relief pilot valve, solenoid valves or manual emergency valve will open the deluge valve, the pressure of the water from the relief pilot valve discharges, will the entire deluge valve installation .water emptying. 17 fire-fighting water spray electric valve repair and replacement 1, turn off the fire pipe water supply valve to open the drain valve to pipe water emptying; 2, disconnect the electric valve electric device control power. 18 fire hydrant maintenance replacement .close fire hydrant water valve, open at both ends of a fire hydrant relief or drainage. 19 fire pump overhaul fire pump control knob for the "cut", disconnect the motor three-phase power supply air switch, turn off and out of the water .valve, discharge pressure of the pump body, finished. 20 110, 220kV switching station to carry a ladder when safe distance, and put down after two handling. 21 installation pipe flanges and valves of screws is the qiaogun correction screw holes are not permitted to .use the finger into the screw holes in touch..

Weak current College】【Central air conditioning & refrigeration industry nomenclature resolution (2).

1.7 evaporation and boiling Evaporation refers to free-surface liquids gasification process. For example, water evaporation. Clothes dry process. Evaporation on the surface of the liquid is due to the high energy of .molecular overcome liquid molecules of gravitation, wear out liquid reaches of space. In the same environment, liquids, the higher the temperature, the faster the evaporation. Refrigeration engineering, many issues are related to the evaporation process, such as cooling and humidification of air .conditioning and drying process. Infrared humidifier humidification is surface evaporation process. Boiling is the liquid inside the bubble forms of violent gasification process. For example, the process water to the boil. At a certain pressure, the liquid is .heated to a certain temperature began to boil. Throughout the boiling process, liquid absorption of heat all for its volumetric expansion and the gas-liquid phase transition temperature remains unchanged. If the electrode humidifiers belongs to the boiling process. .1.8 thermal conductivity (also known as thermal conductivity) Thermal conductivity is a materials transfer heat capacity of a physical quantity. If two equally thick material, one is a copper blocks, one is a cork blocks, put them in .the high temperature than itself, you can feel the copper block temperature, and the Cork block you feel in a short time. This description of two materials on heat conduction of different capacities, the materials on the thermal capacity of different transmission to digital representation is .called thermal conductivity, its value is equal to: when the material layer thickness on both sides for the lm, the temperature difference of 1 ° c, the surface area of over lm2 1h the conduction of heat, the symbol l, units are kcal / .mh ℃, the State's legal units is W / mK or use J / mhK indicated that conversion between them is: 1W/mK = 0.860kcal/mh ℃. Different materials have different thermal conductivity, and material composition, .density, molecular structure, and other factors. The same kind of material, the thermal conductivity of the main factors is the density and moisture. Density, thermal conductivity, thermal conductivity of high humidity is also high. 1.9 heat transfer coefficient When you freeze a substance, such as in surface blowing it freeze faster than not blowing time fast. Represents the different substances in different States heat capacity of the physical quantity known as the .heat transfer coefficient, its value is equal to the hourly, every square meters area, when fluid and solid wall for temperature-difference between l ° c the transfer of heat. To sign a representation, its units as kcal / (m2h ℃), .the international system of units is W / (m2k) or J / (m2h ℃), the relationship is between the two conversion: 1W / (m2K) = 0.860kcal / (m2h ° c) 1.10 heat transfer .coefficient Heat from the hot side of fluid through the flat wall transfer to low-temperature side fluid. This heat transfer capabilities in addition to temperature, heat transfer on both sides and the size of .the area concerned, and the flat wall heat transmission coefficient, flat wall thickness of the walls on either side of the heat transfer coefficient. All factors column into a single formula, namely: Q .= KFDt (kJ / h) Type: Q: transmission of heat (kJ / h); F: flat wall surface area (m2); the temperature difference Dt: Dt = t1-t2 (° c) .; Heat transfer coefficient K: kJ / (m2h ° c) K is heat transfer coefficient, it numerically equal to the temperature difference when the sides l ° c, heat transfer area by lm2 .lh, thermal fluid from one side to another side of the cooling fluid transfer of heat. Unit is kJ / (m2h ° c) or W / (m2k). 1.11 specific volume and density Unit volume of moist air has the quality known as density, wet air per unit mass of a volume called the hematocrit. 1.12 humidity Humidity is humid air containing water vapor content in the number .of physical quantities, there are three types of representation. A £ ® absolute humidity Lm3 wet air steam quality. Symbol for Z, unit is kg/m3. .V: steam volume of possession, that is, the wet air volume, expressed in m3. Absolute humidity is not convenient to use. It does not directly reflect the humid air of dry and wet. < .br> B. amount of wet Per kg of dry air containing water vapor amount known as the moisture content, symbols for d, unit is kg / kg (dry). 1.13 dew point .temperature Under certain atmospheric pressure, moisture content does not change the steam condensation in the air to water (DEW) temperature. Unchanged at d, air temperature, from unsaturated State becomes saturated, air relative humidity j = 1O0 per .cent. In the air conditioning technology, the air temperature and dew point temperature, air dehumidification drying. 1.14 enthalpy Enthalpy wet air is an important parameter. Is a bit with the pressure inside the .can of composite state parameters. In the air conditioning process, often moist air state changes, enthalpy can easily determine the status of the change in the amount of heat in the process. Humid air change process is the process of .constant pressure, enthalpy difference equal to the heat capacity, namely: tDh = DQ = cmDt Type: Dh: enthalpy difference kJ / kg (dry) DQ: heat capacity kJ / kgm: .kgc moist air quality: humid air of the constant pressure heat kJ / (kg ¡ã c) 1.15 static, dynamic pressure, pressure In the select air conditioning or fan, you often encounter the static and dynamic pressure, .pressure these three concepts. According to the role of knowledge on fluid mechanics, fluid in the unit area is called a vertical force on pressure. When the air flow along the wind pipe wall, the pressure can be divided into static and dynamic pressure and full .pressure, unit is mmHg or kg/m2 or Pa, China's legal units is Pa. A. static pressure (Pi) Due to the irregular movement of air molecules and impact on the wall .is called a hydrostatic pressure. The calculation to calculate the absolute vacuum is called absolute zero of hydrostatic pressure. To atmospheric pressure to zero pressure is called relative static pressure. Air pressure means relative static pressure. Static pressure above atmospheric pressure, is positive, lower .than the atmospheric pressure is negative. B. dynamic pressure (Pb) Means the air flow pressure, as long as the wind tube air flow has certain dynamic pressure, its value is always positive .. C. full pressure (Pq) full pressure is static and dynamic pressure of algebra and: Pq = Pi x Pb full pressure represents lm3 gas with total energy. If the atmospheric starting point for the calculation, it can .be positive, it can be negative. .

Weak current College】【compressor considerations when connected in parallel.

1. maintain oil surface 2. back to the solution of 3. protective devices? parts department products plant 4. confirmation of piping stress (Which maintain the oil .surface is the most important issue) 1 keep the oil surface (1) Compressor parallel use, because the compressor oil quantity and volume of the oil system, long operation will cause the compressor for .oil changes (party oil surface reducing, rose oil face a party). If】【drawing 1-1. Connect to the same type of compressor A and b, if the compressor of A oil is .high and the system back to A small quantity of oil, the oil surface will continue to decline, finally appear almost no oil State, causing the damage caused by poor lubrication bearings. Compressor oil quantity of B, and the system back to oil a large .quantity of oil, B will continue to rise, the last motor rotor almost submerged in oil inside, causing the input power increases, the portion of the increase in temperature. Parallel compressor runtime changes the oil surface (= oil .quantity side to the other side of the compressor) is called [partial oil]. The worst time, dozens of minutes to appear on the other side of the compressor oil free. 1 keep the oil surface .(2) Try to make each compressor oil quantity equal to the amount of oil equal suction line, you can extend a State without oil, but these measures are not fully offset the Elimination of compressor oil. . Maintain oil surface method ☆ The design is not susceptible to partial oil system ☆ Occurred after partial oil, we must take the compressor oil back to the initial state of design. < .br> 1 keep the oil surface (3) Avoid partial oil strategy is: ① the same model, with the capacity of the compressor connection, as far as possible on the .oil quantity equal to the amount of oil. / ② compressors of the exhaust pipe to the confluence of the Department, as well as the differences between the Department of the suction line to the compressor, each system's parts are the .same shape, 2 compressor to maintain parity of the refrigerant + oil flow. ③ for further restraint systems on oil, gas pipeline design oil separator, it is best to adopt separation into two compressor oil back into the system < .br> These three strategies ① and ② ③ is must, is necessary. Effect is obvious) 1 keep the oil surface (4) Some time after the operation are oil operation . Both the oil operations, buildings can through both sides of the exhaust pipe, the compressor suction tube for all oil can even work?, very long time. »Effective way is through tubing connection .2 compressor oil storage location, move the oil through tubing. ? Both oil operation of representativeness, through the following order for a short time both compressor ON-OFF (Note 1), correct partial oil. 【Figure 1 .-2】 ① stop a compressor (OFF), 2 minutes: oil will move through to the operation of both tubing (ON) side of the compressor ① ② instead of .ON-OFF relations in 2 minutes: oil will move through to the operation of both tubing (ON) side of the compressor ③ restored to their original running state (both restored to operation status (ON)) Use the attention of the tubing Note that if you set both operate in the conventional oil, oil level changes will accelerate (Note 2). Not all tubing, oil surface only through the .exhaust pipe and suction tube slowly changes. However, the settings are tubing, normal operation and also through tubing oil flow, causing oil level changes to speed up the phenomenon. This problem, you need to reduce both oil operation interval or have installed solenoid valve .tubing, only allow operation connected are some solutions such as tubing. Note 1: 1) here is an example of setting frequency, frequency + fixed-frequency connection, the frequency has been ON .status, frequency of repeated for low-speed operation (oil from variable to fixed-frequency) and high-speed rotation (oil moves from fixed frequency inverter) are oil. That is, by repeatedly changed sides of oil pressure size for both oil. . 2) extend the party compressor stop time, running side of refrigerant gas compressor will be condensed in stop logging on the compressor of the exhaust system, affecting the trust of measuring the compressor is stopped. So you want to shorten .the stop time. Note 2: Through tubing for oil mobile can be explained by the fact that both sides have save oil pressure difference (1/1000MPa degree of variance), and through this pressure difference, .the compressor oil in a large number of fine particles can move. Fine oil is very light, even slight pressure difference you can also move, you can drop in a short time to cause poor lubrication the oil surface. 2 .back to the solution of Too avoid partial earlier in important matters, oil pipeline shape equalization to reduce excessive back to fluid phenomena is also very important for the design project. If the pipeline shape, lead to the two sides back .to fluid, will be back up many occurred within the compressor, as well as liquid compression to reduce the oil concentration causing poor lubrication. In addition, the shape of the suction head separation is also a back-up of .the major issues of equality. Than simple T words separately, fluid can be divided in sleek Y words separately more ideal. 【Figure 2-1】 Whether due to fluid cause liquid compressed confirm ., you need to stop by for a long time, after defrosting time IN and OUT of the machine to confirm. No matter which one, you need to consider the refrigerant filling quantity of maximum deviation, and the short pipe is in need of strict consideration .and implementation. 3 protection device accessories parts of equipment (1) Often running 2 compressor (both oil operation is another), but also to the ability to adjust to only operate when one compressorWait ., so the protection devices and accessories from different parts of the configuration. Only do while running, it is best to 2 compressor has shared 1 high voltage protection (HPS), low-voltage protection (LPS). But .exhaust pipe temperature protection of each compressor must be installed. Compressor motor protection (IP) and the crankcase heater bands also needs to be installed separately. All tubing due to use of the electromagnetic valve set (reference 1) Above .,】【Figure 3-1 represents only at the operation of connection points. 3 protection device accessories parts of equipment (2) Only running one compressor, first ., you must stop the side of the compressor installation globe valve exhaust pathway. You can prevent stop when the countercurrent and refrigerant condensing, put liquid refrigerant compressor. (1 * Note 1 Reference) High-voltage protection (HPS .) need individual installation, low-voltage protection (LPS) preferred shares for 1 low-voltage protection. Exhaust pipe temperature protection must be an individual installation. Compressor motor protection (IP) and the crankcase heater bands need individual installation. All tubing due to .use of the electromagnetic valve set (reference 1) Above,】【Figure 3-2 indicates a party to the operation of connection points 4 confirmation of piping stress . Because of the connection tubing is complicated, the system has been added, so it is best to conduct oil piping system stress damage to confirm. The following instructions to confirm the stress profile 【Figure 4-1 .】. (1) stress confirmation Stress confirmation, you must use the stress table from physical measurement First of all, the real start .measurement, it is a good idea to do a piping system stress analysis, confirm that the stress concentration point (= install stress table place) where stress is centrally, Piping of the root of the fixed part (example: .compressor shell, contact Department, etc.) → 【Figure 4-1】 ○ parts Piping fixed part of the first bending Department → 【Figure 4-1】 △ section The determination of .parts requires X, Y2 direction determination】【Figure 4-2. (2) the recognition criteria for the determination of the kind Real confirmation, in standard conditions .running conditions. ☆ The compressor ON or OFF "introduction start stop time", whether dramatic stress, whether occurring more than piping materials elastic limit stress? (example: stop state two compressor at the startup and operating conditions are .oil has only one compressor start stop) * Power supply voltage, nominal + 10% (compressor start torque max) ☆ Compressor stability operation, whether because of the piping system produces more than pipe .resonance material fatigue limit stress? (example: two simultaneous operation of compressor and party operation) * Power supply voltage, rated ± 15% (in order to master the resonance of deviation) < .br> (3) reduce stress concentration (stress too large of countermeasures) Reduce stress, generally have the following. (Must be in the actual piping system seek solutions) < .br>? Reduce the weight of the piping system ? Design can absorb stress of bending and cyclic Department The Department of buildings increased bending bending radius Case .1 This connection is using high-pressure Chamber compressor system. For low pressure compressor system, cavity must connect back to the tubing between the compressor. ? This figure can be reduced to one oil .separator, installed in the main exhaust pipe, use Y-type connections, and then return to the compressor oil, respectively, in This kind of structure of benefit that can be both run interval lengthen oil < .br>? This form easily overheat operation, the operation of the compressor will be reduced. Case 2 ? If you use this low-pressure Chamber compressor map you want to breathe .in the dispenser for special handling, deliberately let A pressure higher than in the low pressure compressor B low pressure compressor pressure refrigeration oil flow to A one-way from B compressor. Moreover, in the form of A compressor- .based compressor, B supplement compressor (B cannot separate operations), ? There are pressures because B compressor deliberately reduced, causing b COP is relatively low, generally do not use; . .

Weak current College】【electric actuator reliability and maintenance.

Electric actuators can be divided into straight trip itinerary and angle, it is an automatic control system indispensable equipment whose main task is the regulator for the control signal in proportion to the converted into linear displacement or angular displacement to lead the valve, regulator, bezel, etc to achieve automatic control. It is widely used in electric power, metallurgy, petroleum, chemical industry and other industrial sectors in the field of automatic control.

Over the past 10 years, due to the widespread adoption and uptake of micro-computer control, micro-mechanical, and other new technologies, new results and mature experience, electric actuator is the rapid development, has now been widely used "computer + servo system" structural model of computer type electric actuator, signaling completion of the microprocessor, tuning parameters switch, status indication, control of output, to improve performance, use and maintenance of flexibility.

First, the reliability of the electric actuator

Electric Actuator reliability refers to it within the prescribed conditions and within the time stipulated features ability to complete.

"General conditions" can be summarized as:

(1) environmental conditions: refers to electric actuator performance environmental characteristics, such as temperature, humidity, pressure, magnetic, mechanical shock, vibration, dust, etc.
(2) dynamic conditions: refers to electric actuator performance of dynamic properties.
(3) load conditions: means can affect the performance of electric actuator load characteristics, such as torque, charged object types and properties, etc.
(4) the use and maintenance conditions: electric actuator reliability only in use, and maintenance, for use and maintenance conditions, the first thing to note is the perfect use and maintenance; and second, you must require the operator to achieve the appropriate technical standards.

"Conditions" is motorized actuator reliability definition the most important and most obvious parts. Under different conditions, their reliability is a black-out specific conditions on reliability may be meaningless. The functionality of the "requirement" is the characterization of the electric actuator tasks of parameters, such as torque, on/off and time, stroke, fixed time, dead zone, etc.

Electric actuators in lifetime reliability changes is to study the basis of their reliability depends on early failure, failure of random failure and depletion. Common reliability theory (R) it a certain amount of indicators characterizing the reliability of the device, it refers to the device in the prescribed conditions and within the time stipulated features of probability. A simple and intuitive, the electric actuator industry in actual use, simply use the average time between failures (MTBF) characterization of reliability features, and as a representative of the electric actuator reliability of performance indicators.
Electric actuators for reliability in General is affected by the following main factors and influences: System selection and design, component/component, an action parameter, machinery construction, manufacturing, assembling accuracy, operation and maintenance personnel capacity, operation and maintenance programs, operation accuracy, maintenance, Assembly and construction conditions, spare performance degradation, transport and use.

To make electric actuator has many features and outstanding performance, and often had to increase the complexity of the system structure, in order to ensure the functionality and performance in use is put into practice, making the reliability problems. Because electric actuators directly control the unit's operating process, impact on the unit and power plant safety and economy, research, analysis of the reliability of the electric actuator is very important and meaningful.

2. electric actuator failure analysis

Improve the reliability of electric actuators, it is necessary to minimize and eliminate failure, but in fact this failure are many. There is a component failure, some system components/component integrated factors, some are electrical, secondary circuit and external factors. Some failure by adjusting the way you can solve, is due to the long life, poor accuracy, you need to repair and replacement parts to restore its performance, while some are the result of the original design of the desired improvement in order to exclude.

1. electric actuator failure characteristics

(1) the commissioning phase failure

New electric actuator failure problem more complicated, characterized by the design, manufacture, installation and management, and other quality issues are intertwined. Failure to reveal serious, it is difficult to adjust the speed, dirt or grease stability so that the actuator failure jam or action. Some components are missing or misplaced spring loaded, seals, but also belong to the design defect, component selection, the actions are not smooth, positioning accuracy is poor, treat such a failure, you should be patient and meticulous, careful handling, one by one.

(2) the initial and ongoing failure to run

Debugging is in normal production phase fault characteristics are: a small number of seals as Assembly quality and material quality problems in the short term damage to oil spills; originally glued in the pipe wall, the hole wall of Burr, sticky sand, impurities and dirt particles cause certain components of precariousness. General to the running of the medium-term, the system components/assemblies is best run work status, low failure rate.

(3) run late fault

Electric Actuator run time, each kind of symbol/components for the operating frequency and load conditions, all wearing parts wear out successively. Failure of this stage is characterized by a position feedback bad contact positioning accuracy is poor, and stability, efficiency significantly reduce, the failure rate has gradually increased. When should a comprehensive inspection, replacement of failure parts, make do, should not have to deal with ideas, science, strictly determined to be fully invested, repair, or may run staff a lot of trouble, even serious effects unit normal adjustment and control.

2. sporadic, sudden failure

Such a failure in time shown as incidental mutation, fault zone and causes more obvious, by non-human and human factors, such as a bad position feedback device, the brake pad wear and "ABS", Parts damaged, coil burn, seal failure, etc.

3. electric actuator maintenance

Electric Actuator primarily by the motor, bearings, gear system and electronic parts, etc. According to the United States military MIL-HDBK-338 released reliability data showed that the actuator failures are mainly concentrated in the motor and bearings, motor failure: winding failure accounts for 20%, accounting for 45% of the bearing failure, slip ring, brush and commutator damage 5%, other 30%; in bearing failure: lubricants metamorphic, vanishing 45%, 30% of the pollution, erosion, accounted for 5%-5%, 5%, the corrosion of the other 10%. Therefore, good maintenance can complement the reliability of the electric actuator, increase its effectiveness.

【 Weak current College 】 DDC controller configuration principles---Power By 【 China power house network 】

2.1 device number centralized place

Cooling stations, boiler houses, heat exchanger stations, substations are device central place, shall select bulk DDC controller. For example: Honeywell, Excel5000, XL-500, Siemens600, MBC. XL-500I/O point 128, MBC, I/O module 80 (each I/O module is 1 or 2 or 4 points), which can be extended.

For example, a project to bid the book: XL-500 analog and digital input and output when mixed with 650 $/point, pure digital input and output of 400 Yuan per point. XL-50 analog and digital input and output when mixed with 850 RMB/point (the only controller unit price, not including sensors and actuators).

From the economic conditions taken into account by the visible, conditional use bulk of DDC controller is reasonable.

2.2 process-related equipment requirements, configure the same controller

According to the process-related equipment needs to be configured the same controller, this makes it easier to debug and run (monitoring). For example: the same cold station controller to monitor, control, management, except for chillers, cooling pumps, cooling pump, fill the pump, including from cold station installation distance of cooling towers, expansion tank. Heat source system boilers, boiler circulation pump, boiler feed pump, heat exchanger, secondary heating circulation pumps and boiler related exchanger, circulation pump, water pump, expansion tank (including a different installation location) also belong to the same controller.

2.3 press run time and season configuration controller

According to the above configuration, the device is running, in summer, winter outage winter and summer downtime, year-round operation. The following analysis of general engineering equipment operating season.

Summer operating equipment: chillers, cooling pumps, cooling pumps, cooling tower, dedicated cooling station with variable power distribution equipment.

Winter running equipment: heating with hot water boiler, heating with heat exchangers, boilers, hot water circulation pump (a), the heating circulation pump (second), fuel oil boiler feed pump, boiler feed water pump (in addition to the works of domestic hot water steam boiler heat is used for the quarter, the other for winter operation), geothermal, Sirocco screen with heat exchanger and related circulation pump, water pump, expansion tank, etc.

Year-round operation equipment: domestic hot water steam boiler and steam boiler feed pumps, softener, softening water, condensate tank, condensate pumps, air conditioning repair for air conditioning pump, expansion tank, air conditioners, fans, fan-coil line), domestic hot water with a heat exchanger and circulation pumps, pool heaters, circulation and filtration pump, DOSER, water supply and drainage equipment, exhaust fan, elevators, lighting, power supply equipment, water separator, set water, backwater bypass valve (means heating areas), pool, living with fire and water tank.

You can run all year round in a controller, this makes it easier to press the seasonal maintenance controller, system operation is not affected.

2.4 system 2 and above address bus configuration

2.4.1 no network controller

Some products central station and field controller DDC newsletter only with converter in no network controller, for example: Excel500 central station by xpc-500 or Q7055 converter to connect 3 C-Bus bus, each can add 29 stand DDC controller. SiemensS600 central station by 538-675 exchanger can connect 4 BLN bus, each can add 100 DDC controllers, controller requires communication between work, in conditions of placement in a controller, to accommodate the same C-Bus or same BLN bus, so you can ensure that communication is not affected by the workstation failure and still be able to meet the communication requirements of the process. For example: cold station controller and expansion tank, cooling tower controllers are not on the same controller, but the two controllers should hang on the same bus.

2.4.2 a network controller

Some products central station and field controller DDC newsletter intermediate need to install the network controller. For example: Johnson products central station and DDC controllers will need to install the network controller, which exists in different network controller DDC controller under hanging in any 1 network controller failure circumstances cannot, therefore, such a system work in communication requirements should be housed in the same network controllers hang bus.

2.5 press monitoring object to configure the installation locations

When the monitored object is set to installed across the room, adjacent room and adjacent floors, and is not related to each other mutually independent should fully use DDC controller capacity arrangement in a controller, if you have richness I/0 points, wiring length and to the extent permitted in the product, and is independent of unwanted and other points of DDC newsletter can be arranged in a controller. (SiemensI/O line up 230m, DI/DO: 14AWG-22AWG, AI/AO: 18AWG-20AWG).

2.6DDC controller after comparing different configurations, and then do recommend programmes

On the project according to the monitoring, control, management, equipment and distribution locations, on-site requirements, using different controller configuration options, you need comprehensive comparison to decision recommended scenarios. For example, an engineering equipment distribution, functional, monitor content management requirements has been established to consider the conditions, the use of DDC configuration XL-500 centralized configuration, or with the bus expansion through Lon-Bus XL-500 programme, or a combination with XL-500 and XL-100. When using MBC extended programmes or MBC and MEC combination programme, even there are also multiple scale and MEC MEC configuration scenarios, you need to do some work, from a performance price ratio,Comprehensive comparison with maintenance and do recommend programmes.

2.7DDC controller monitor target for air conditioners, a new fan of configuration

In high-rise buildings, many of the same functions, the same plane of floors, air conditioning equipment layout is the same horizontal position on the same device number. DDC controllers generally choose 1 medium controller 2 conditioner or fan, or a device number often should use large controller. This configuration uses a different controller to monitor, control, management towards the South and North more reasonable. So in the preparation of the post, downtime, temperature setting is on (toward) by groups, and even the floor and towards the group preparing the schedule to run more convenient.

3DDC controller to monitor, control, management principles

DDC controller is building equipment automation, the most important component, it can compile stored procedures, make the device according to the procedure runs, you can capture devices, various preparation, operation, transmission failure status to the workstation, and accept the various command workstation timely transferred to the device and executing agencies to complete the command, it can be seen DDC controller in important role in the system.

DDC controller for building air conditioning ventilation system, the heat source and switching systems, refrigeration and cooling systems, distribution systems, public lighting, elevator and escalator systems for monitoring, control and management. But in design to the implementation of national, sectoral ministries procedures, specifications, requirements, the following talk about the views of the author.

3.1 and fire facilities interface

3.1.1DDC controller cannot monitor firefighting equipment and facilities

Belongs to fire special equipment and facilities are: water, fire fighting hydrants, spraying pumps, with exhaust smoke machine, positive-pressure blowers, fire shutter, fallout first floor elevators, fire elevator, fire elevator catchments sewage pumps, fire, emergency lighting, evacuation signage lights, emergency broadcast, power supply for fire-fighting, fire water storage tank and dedicated exclusively to high water.

3.1.2DDC controller monitoring work and fire equipment and facilities

(1) underground layer of smoke machine: usually design in typical double as exhaust fan. However, a two-speed motor single duct system, low-speed to normal working time exhaust, DDC controller should monitor. When using high speed to fire, the fire controllers monitor. Another is the dual-motor, motors, capacity, often small air motor is typical exhaust, DDC controller should monitor. Another large amount of wind and small air fan is used, when the fire by a fire controller monitoring;

(2) a basement blowers: some works will double as a fire in the basement of blower air, meet regulatory requirements by 50 per cent of the amount of exhaust smoke. This class of device DDC controller in normal working hours should be monitored, as a fan. In fire by a fire starting and stopping the controller monitors and open dedicated outdoor air valve, close the air valve;

(3) the combined domestic and fire water storage tank or high water;

When life and fire and the cistern, the water level drops slightly higher than the fire water level signal, from DDC controller detection after low water level alarm and stop watch domestic water supply, to find causes, to the sink in water, is situated slightly lower than the overflow water DDC controllers with high water level alarm (if set water electric valve, received high signal, the water supply should be immediately shut down the electric valve), duty to find the cause. When the water level below the fire water tank, fire controllers receive low-water signal and the issue of low water level alarm signal.

When life and fire combination of high water, the water level drops slightly higher than the fire water level detection by DDC controllers, should immediately to pump water, but if the water level drop bottom-fire water level, not for living water (use of living water supply pipe installation to restrict elevation), the signal received by the fire controller alarm signal, after find reason. watchkeeping personnel When the water level of a high water tank overflowing level, DDC controllers with high water level alarm, to immediately stop the pump.

3.2 and corresponding electronic control device interface

3.2.1 elevator centrally monitor disk

In the selection of elevator central control disc project, DDC controller is not necessary to monitor the location of elevator cabin only monitors the operating status and fault.

3.2.2 no elevator centrally monitor disk

No lift to centrally monitor disk works, generally only monitors the operating status and fault alarm. To monitor the position of the box, "Beijing Desheng Guosheng information system engineering co., Ltd." binary encoder practices so that you can save a lot of DI. For example, a 30-story building will save 25 points.

3.2.3 sewage pump

General high-rise building have sewage pumps, and supporting electronic control, it is as level (supporting) automatic starting and stopping. DDC controller, therefore, should not be monitoring the starting and stopping only monitoring fault alarm, automatic State, running, or select the level sensor. But owners ordered sewage pump to explicitly provide liquid level sensors and introduced watch the terminals, and requires the manufacturer to DDC controller required contacts connected to terminals.

3.2.4 frequency live feed pump

Many projects use constant pressure variable water supply system. Basically it is supporting EFI electronic control equipment, pump starting and stopping automatically run under pressure. Therefore, DDC controller only monitoring fault alarm, manual, automatic State, running state. Simply matching manufacturer will DDC controller required contacts connected to terminals.

Friday, March 18, 2011

【 Weak current College 】 decoration budget five common failing in

Most modern people admitting to the decoration. So before you do, the renovation budget result in significant cost overruns; decoration, wall paints colorful, bright and colorful, can live a long time but the brain increase dizziness; buy the furniture bought together, not two years out of date, or throw or ... These issues become the most common of the owners.
Problems of a breast with no global
Many prospective owners to get the new key, haven't planned immediately decoration, decoration style from selection when lost and don't know which style is more suitable for yourself, all depends on the loading edge checkpoint… side, as a result, the decoration effect differs quite, the decoration budget overruns a lot too.
It can be proposed, yet decorative products of prospective owners to get the key, don't worry, you should determine the decoration style, including the use of decoration materials, furniture purchase and placement, and other details will be aware of. And then combined with decoration style, their financial capacity, determine a budget, and in the construction process to control the budget.
Next, delegate a reputable, reliable construction quality, prices of decoration companies, will your investment situation, on the functional requirements of the specific housing clearly, decoration companies in design, decoration for you. At the same time, you should go to the site, at any time and the construction unit consultations, improved local original is the perfect place to get the most ideal decoration effect.
Two small gains common failing
In fact, many repair disputes are consumer gains psychology. For example, many consumers to save money, hire an unlicensed construction team for decoration.
The construction team is usually only 35 people, to undertake projects, first of all to low prices to attract customers, commitment to customers want to pretend like you pretend to like. Once an agreement has been reached, the use of materials such as decoration on shoddy will woes, even on a landlord renovation remaining material to use.
Secondly, the completion of the contract still could not be completed, the longer the construction front drag on. In the area of environmental protection, many property owners in the decoration of the end of several months can not be accommodated because indoor taste make people afraid to normal breathing.
It can be ºæ·éð¹ã¸æ decoration team advise prospective owners: what you pay for a penny. Decoration of this money, the province may not.
Common failing three firmly
Decoration, you find a lot of pretty pictures, also bought a lot of fashion and home magazines. Decoration, you carefully selected pictures show it to the designer view, but not a designer for your new home.
In fact, the appropriate references and reference is necessary, but simply imitate, completely unnecessary. A good decoration effect, from the use of materials, color matching, layout arrangement, lighting configuration, decoration of display, green dot and personality is reflected in many aspects. The same decorative styling, in another person's residence is well proportioned decent, but use at home only to clutter.
Recommended that prospective owners and architects timely communication is very important. Before the construction, prospective owners should promptly told the architect's own needs and type of your own home, you purchase the furniture, how to put these furniture, also need to purchase what accessories with designers achieved consensus, a real decoration for your home.
Four common problems in one step
Young Coverly is very easy to walk into a misunderstanding, to "one step", doing wall-to-wall cupboards and some fixed furniture. The large sofa in the living room with a large wall or bookcase; the bedroom is the wardrobe, large bed, eyes is not dynamic furniture, a long time no longer be able to make changes and adjustments.
Decoration should do with environmental change. Different seasons replace matching home accessories, master of mood changes as the home to produce fresh; the changing of times new home trends, home design ideas, furniture of style will change; more importantly, when two people of the world into a family of three, how reasonable partition and use the housing space, master also needs readjust.
Therefore we recommend that new House decoration must be "blank space" to accommodate future changes leave enough space. Disposable complete decoration creates a lot of waste, making the owner in relocation housing, on the one hand, I do not know how to design, one hand also throw outdated furniture.
Common standards for five blind
Many people decorate the House like the wind, the pursuit of luxury, others are also blind pursuit, regardless of their actual situation, the result of a decoration down consumption to several hundred thousand dollars. In fact, the excessive consumption is prospective owners a very immature consumer psychology.
In fact, modern decoration emphasizes "light decoration, decoration", many parts of the body is really no need to "fight". For example, most of the housing's internal only 2 meters high, do the "ceiling" of decoration is inappropriate. Hanging out of the top even beautiful, easy to give people a sense of oppression, it is better to stick with some wood or plaster decorations; the more upscale decoration materials may not be possible, the use of quality materials, each square meters can save tens of costs, with the money to buy some upscale atmosphere of furniture and electrical appliances, more practical and beautiful.
The modern decoration of the concept should be small, green, warm and comfortable living is the most important. "Blind complaining" invest relatively large proportion, occupy more interior space, because the use of toxic materials, on physical and mental health are also very negative.

【 Weak current College 】 elevator maintenance experience with frequency converter

A Mitsubishi A540-55K converter, this machine could have broken a module, for good measure, to the rear drive is functioning, the trigger line dial-out module, resulting in a power check on the trip, found and burned a module IGBT module so the trigger-line dial triggered off may have a small amount of voltage, this module is half powerup on-State, a short-circuit Burnout as a result, this characteristic GTR module to this test!

Many Mitsubishi A240-22K converter, all bad module! because maintenance is not good, such as radiator dust multiple plug, circuit board is too dirty, thermal grease failure, etc., this inverter output module (PM100CSM120) is an integration module, is bad all the way to the entire change, maintenance of high prices! good module also hard to find! if you haven't broken the inverter, you have to careful maintenance!

A Yaskawa 616G5-55KW inverter, badly damaged and it turned out to be a fast fuse (three-phase has a fast penetration), electrician may have no experience, no checking module of the problem, but also unable to find fast melting, replaced by a copper wire, turn on after a loud crack, two modules, the absorbing circuit, driving Board is unable to repair, replacement plate, resulting in substantial losses if the module is mostly fast fuse, but bad fast melting does not necessarily replace broken! copper melting faster had seen many times!

Often someone in the Mitsubishi A240-5.5KW inverter when exchanging A540-5.5KW A540-5.5KW "N" line earthing! a transmission frequency converter is gives bang!-converter damaged!, on the one hand the "N" A540-5.5KW line and A240-5.5KW inverter ground position similar to the electrician didn't! clear grafted in the ground; some are mistaken for electricians "N" line is ground! please Mitsubishi inverter users be careful wiring!

Appearance like how to detect the current module, is actually very simple, just use the capacitance meter, detect module C-E G-E or electrical capacity, the current capacity is big! attention to similar modules in comparison!

Try to Converter output voltage converter you find over 1000 volt (enter 380V), asked whether there is a frequency inverter fault? burn motor? he also did not understand the converter will only boost buck, not the original he is!! digital multimeter measurement, because the converter output voltage is high-frequency carrier, no anti-jamming measure digital table here is very inaccurate!
In the Mitsubishi A540 auxiliary power inverter (R1, T1) wiring is not off the shorted tablets, results in the inverter burned after also could not understand his reasons, the original when shorted tablets didn't take off, the inverter internal R and R1, T and T1 is already linked, the electrician thought from R, T has two lines, the result put T R received the S1, R1, white received short circuit, R1, R and T and T1 line is via power plate's middle tier, as a result the power Board burn burst open into two layers! in general there is no need to add auxiliary power supply (R1, T1)!

When the maintenance frequency converter does not know how to use fake load, when the driver is at fault, burned the module after said module quality! false load is one of several hundred European resistance (light gun can), conspiracy in the main loop, such as a fast melting put it away, loading resistance; no fast melting in the main back to anywhere on this disconnect, conspiracy! this resistance to current limiting resistor, when the module is short-circuit will not burn down the modules, etc. after powering the normal measurement transducer output, before this fake load pulling!!
Many factories-powered generator is, when generating a fault, the output voltage often converter and electronic instrumentation burned! there's one last year for Shenzhen home-drawing factory once broke down over Taiwan 30KW inverter, cut off 10 days, causing heavy losses, the factory in generator made many protection method may not be obvious! a later we want passive protection methods, Inverter or instrument input air switch plus a varistor (380V, with 821K 220V471K) so when a high-voltage, pressure-sensitive will short circuit, air switch tripping, protection of the frequency converter, inverter fault rate is significantly reduced, varistor is cheap, this method is to spend money doing big things!

Parallel (three-phase is a Delta connection) of varistor wattage sizes not strictly required, enter the current of the selection of varistor relatively little (or a few parallel)! when varistor unlit when it is completely short-circuit! now also requires that you have good quality of air switch, responsive! protection current and not too large!, of course, is received by the local air switch output!

Speaking of varistor, a converter which input also varistor, should also have guaranteed! minor injuries by just blowing circuit board of copper wire, serious injury to burn the rectifier module, switch power supply, CPU board, capacitors, causing serious injuries may be when a varistor short circuit when its metal debris flying everywhere; explosion issue strong electrostatic and electromagnetic waves (very much like lightning strike); blow Board of copper wire make air switch not actions. Therefore, in the converter outside the other pressure sensitive resistor is much better!

Some people buy the module requires model a verbatim! actually completely unnecessary, as the module parameters with 7MBR25NE-120 7MBR25NF-120 is the same, only more of the four positioning feet! because IGBT module driver is voltage control, better interchangeability, as long as the voltage, the current parameter, a different model IGBT modules are interchangeable! have sizes of installation can also be another boring! GTR module you will also need to consider its magnification, interchangeability narrowly! we repair the inverter so cheap it is to take full advantage of the module interchangeability, avoid using the module on the market, sell, otherwise the module price high or hard to find!

How to choose a module: Maintenance frequency converter, judging the quality of the module is key! first you want to see the module is opened too (see appearance marks), and now has many modules are maintenance, parameter correctly but the quality is very poor! pressure value is the most important parameter, the available voltage 380V, enter the measurement of inverter output module voltage value is greater than 1000V, 220V, 600V! current available capacitor comparison table to determine the size! IGBT module can also be used analog multimeter 10K stall detection if it is capable of action, use the pointer (black-red) to trigger module G-E enables module C-E breakover, when G-E shorted, C-E close! this method is the simplest and most basic measurement method, is the maintenance of the novice to the professional may not measure!

Screw did not tighten! look like, but on the inverter is deadly! there are a lot of inverter when mounted on a vibration device (such as industrial washing machines, machine tools, etc.) to run for a period of time, its main circuit connection screws and tighten the screws of the module is easy to loose, in which the first damage is usually a module, if the module has no other screw-fastened, the module will soon broke down, complained that the module quality! also placed special emphasis on not to inverter mounted on vibration device, otherwise good converter may soon broke!

Often see maintenance frequency converter not fake the results of a load, or burning module can load with fake!, almost can be forearmed! unless you buy are counterfeit module!!

Fuji G9-5.5KW inverter rectifier module CVM40CD120 structure Description:

Rectifier parts: R, S, T, A (+) and N-(-)

Charging SCR: A, P1, Gth (trigger)

Brake pipe: DB, N-, G7 (trigger); DB, B + is its continued flow diode

Power switching valve: D8, S8, G8

Th1, Th2 thermistor:

Mountain Ken MF series has a common failing is sometimes displayed "Erc" failure, then you can do the following: open the parameters, write "90", in which case the inverter 7831 show "PASS", write "number" converter capacity, then the value parameter to restore factory (parameter 36 = 1)!

Inverter capacity: 2.2KW-233.7KW-247.5KW-26

15KW-2822KW-3030KW-31

45KW-3375KW-35110KW-37

Other power and so on!

On the elevator inverters daily maintenance: now the elevator are frequency converter to control when the converter failed will give many people the inconvenience, but also sharp bad managers, if you usually have to inverter for maintenance, you can significantly reduce the frequency of failure rate, we maintain a large number of elevator inverters, summing up the usual maintenance of several issues to note:

1) elevator electric apparatus room temperature must not be too high, or the converter component is easy to aging, air-conditioned, the effect is pretty good!

2) prevent the rain soaked, usually on the scraping of Typhoon, Windows blown out the inverter from the rain.

3) lightning, this is the entire building or lightning protection throughout the community, being struck by lightning on facilities of inverter General badly damaged.

4) converter cooling fans to scheduled cleaning dust, found that there is sound or not functioning to be replaced.

5) Elevator motor abnormal noise is usually a problem, such as inverter motor three-phase current unbalance, then it is best to repair, wait until the inverter full occurs, you may be seriously damaged. If you do not have maintenance experience don't own maintenance, many people get worse converter.

Weak knowledge of building control