【 Weak current College 】 how to choose the most suitable video conference system?

Video conference system and hardware, software, networks are closely related, every business is different from the actual situation, the required video conference system are not the same, comprehensive analysis and communicate with manufacturers to choose the most suitable video conference system.

Divided by network platform, video conference system can be divided into based on the private network video conferencing system, based on a mixed network and the Internet public network video conferencing system. By constructing a modal split, video conference system can be divided into software video conferencing and hardware video conference, video conference system major general portfolio expansion MCU multipoint controller/meeting room Terminal \PC desktop Terminal/phone access gateway (PSTNGateway) \Gatekeeper (gap), etc. Press Conference-quality Division, and standard definition video conference system and high-definition video conferencing system.

Laying network while it is possible to guarantee meeting quality, but much higher input costs, on the development of SMEs is not appropriate. In fact, the Internet has developed very well, even the cheap ADSL line can also provide more bandwidth, 384Kbps such bandwidth fully able to meet the video conferencing application clear and smooth. Therefore, generally choose public Internet suffice.

Using purification of PC-based software solutions while meeting the software itself costs is not high, but each room is also equipped with a dedicated PC, separate video and audio capture device (e.g. USB camera and headset) and the operating system and other related infrastructure software, installation, maintenance overhead, taken together, its cost is low. And pure hardware solution can not only perform high quality meeting and can be highly integrated integration all the features of the terminal equipment is complete without the other with other hardware and software facilities, the plug and play, using simple, maintenance-free, therefore its comprehensive cost than pure software cheap. Overall, pure software more suitable for the individual Office deployment (based on an existing Office PC), pure hardware conference room is suitable for deployment.

2007 SD video conferencing is still the mainstream market, occupying 93.60% market share, which represents the future of technology trend of high-definition video conferencing only 6.40% market share. High-definition video conferencing system advantage manifests itself in several ways: high resolution formats have increased the number of pixels can improve picture quality, make big screen picture more clear, smooth, and smooth clear video quality, high-quality sound effects can enhance attendee's conference experience to help participants to focus on the content of the Conference itself; at the same time, the high definition picture can make large screen image also has a clear video images that more participants appear on the screen, allows more attendees; high definition of high resolution images, to clearly show the details of the content, especially in the graphics operations (such as design drawings, animated discussions, topographic maps, etc.), relying on the Visual communication remote personnel, have great benefits. And compared to standard definition video conference system, costs more, on network requirements are higher.

Enterprises should be a comprehensive analysis of the company's actual needs, including input costs, network bandwidth, device management, choose the most suitable for their own video conference system.

Weak current College】 【elevator operation management.

<br> <br> Elevator equipment operation management, is the guarantee of the good operation of the elevator of management activities. The main contents include: elevator equipment run inspection monitoring management, Elevator exception occurred in the management, management of elevator machine room and .elevator files management, etc. <br> First, the operation of the lift equipment inspection monitoring management <br> Visit monitoring management, by elevator watchkeeping, scheduled on elevator equipment inspections, inspection and found the problem in a timely manner. Elevator watchkeeping daily .on the elevator for a visit, according to the inspection of fill out the "elevator equipment inspection records as table 4-7-1. <br> <br> (1) the establishment of inspection monitoring management system <br> Company engineering Dept .of elevator administrator, according to the elevator performance and operation of developed elevator inspection management system. And supervision to perform watchkeeping. <br> <br> ① on duty daily on the main part of the elevator inspected once. <br> <br> .② visits on request inspection of contents carefully. <br> <br> ③ timely processing of visiting your problem and do the inspection record <br> <br> (2) inspection of contents <br> Watchkeeping inspections should note: traction machine if .there is noise and smell, is hot; bearing bolt is loose; gear box oil, the oil color is normal, the axle for solid and reliable; indicating instrument, LEDs, each relay has normal; transformer, reactor, and so is overheating; .actuator is normal; traction wheels, Dray, speed limiter, etc. is normal; telecommunications facilities, badges, spare wheel and driver and rescue tool will wrench is placed in the specified location; there is no vibration elevator, switch door is smooth; pit .speed limiter is normal. <br> <br> (3) the negative situation found in inspection processing <br> When the inspection found a bad state, watchkeeping shall promptly take measures to adjust. If the problem you should promptly report company engineering Dept .head, in collaboration with the competent for resolution. Repairs should be strictly adhered to the elevator maintenance standards. <br> <br> Second, the exception handling management <br> When the elevator exception occurred in the work of the Division of the staircase .and lift personnel are cool, keep a cool head, in order to seek a safer solution. <br> <br> (1) the disposal of fire <br> <br> ① When floor fire, Elevator watchkeeping duties should immediately try to .press the "fire off" so that the elevator into the fire in the running state. Elevator to the base station, passengers quickly leave the cabin. Telephone notification Engineering Department and dial 119 phone alarm. <br> <br> ② Wells road or .car in a fire, the driver should immediately stop the escalator and commuters leave, cut off the power after dry chemical fire extinguisher or 1211 fire extinguishers fire. At the same time, the phone informs the Engineering Department. If the fire is hard to dial .119 phone alarm, in order to guarantee the high-rise building in personnel and property security. <br> (2) elevator was flooding at the time of disposal <br> The elevator was flooding of the tunnel, Elevator stopped on the second floor .above; flooding when the floor, Elevator stopped in the water flooded in a layer, and then disconnect the power switch and immediately organization personnel, raw water shutoff is blocked after the dehumidification process, such as hot air blow dry. Using shake table test insulation .resistance, standard, you can try the ladder. On the staircase only when you can put to use. <br> <br> Third, the elevator room management <br> Elevator watchkeeping, company engineering Dept elevator administrator under the leadership of the work .. Elevator administrator is responsible for formulating the elevator room management system. Watchkeeping strictly enforce the elevator room management system. <br> <br> (1) elevator room management system <br> <br> ① non-room staff are not allowed to .enter the engine room, must be entered after the company engineering Dept Manager have agreed that in the engine room staff escorted. <br> <br> ② room should be equipped with adequate fire equipment, free on flammable and explosive substances. <br> .<br> ③ weekly clean room health, keep clean room. <br> <br> ④ to avoid unnecessary trouble, the engine room to lock at any time. <br> <br> (2) the shift system <br> < .br> ① normal shift in time. Shift workers should take over staff speak out on the day of the operation of the elevator, succession staff should review the elevator equipment inspection records, tools, etc., confirmed after running inspection record signature. <br .> <br> ② When he takes over the post staff, shift personnel shall not away. Should ask the Engineering Department elevator administrator seeking solutions. <br> <br> ③ elevator accidents, is not processed, should shift personnel continue to be responsible .for incident handling, succession staff to assist in handling. <br> <br> 4. lift the archive management <br> In order to understand the overall situation, Elevator engineering team to build high-rise buildings for the elevator profile. The archives .include: elevator lift with schematics, installation diagram, the elevator equipment inspection records, the elevator equipment maintenance records and other items. Archives of the elevator equipment inspection records, the watch head finishing a book every month, the Engineering Department elevator administrator. <br .> <br>.

【 Weak current College 】 warm IX errors

First, the water warm moist, electric heating and drying?

Water floor heating of water is heated by the carrier, is not the role of regulation room humidity. Warm and comfortable or not dry because of the low-temperature radiant floor heating is heating the envelope's heating, low temperature and radiation both determines how high his comfort. If the estimated indoor moist so that everyone would have a headache, that means that the heating system may leak.

2. home installed air conditioning and floor heating is installed, is not a duplicate investment?

Of course not repeated investment. Air conditioning is the biggest refrigeration, heating function is his Deputy if air conditioning heating in winter is not only a waste of resources, and costs will be high. But the floor heating is a professional, not only saving zhinuan, are not very expensive, therefore, whether from economic accounts, or heating comfort, a warm air conditioning also do, is not wasted, not to be repeated investment.

3. control of water temperature low temperature water supply can be implemented

All responsible European boiler manufacturers do not recommend or oppose, directly to boiler water temperature down to meet the warm temperature water (no more than 60 ° c) the risk is likely flue gas condensation water and seriously damage the boiler service life, Germany heating system most used fixed water temperature constant mixing equipment on a second regulation, there is another way is based on the climate temperature on water temperature compensation adjustment, which can further conserve energy, reduce costs.

4. heating heating rate the sooner the better

Floor-heating radiant heat determines how its reach housing heat balance will be a long process, generally the initial need 6-7h time, and for system debugging may need longer, according to Germany to warm the standard, does not allow to shorten the time and improve the water temperature, whichmay cause cracking of cement and floor tiles

5. the surface temperature is higher, the better

In Europe, the low-temperature floor heating both for saving energy, but also for health requirements in Germany to warm after 30 years of development, and related medical research also indicates that the surface temperature does not exceed 28 ° c, could reach 30 degrees centigrade, local, and if the ground surface temperature over the safe temperature, it can cause vascular dilatation of the body and cause a variety of diseases.

6. heating is very simple and does not need to design

Many customers that heating is very simple, only need ground covered tube can, in fact, this is the biggest mistake. Warm as HVAC professional is a new technology, design than traditional radiator system more complicated, because the design is the foundation of good construction, design reasonable or not directly related to and affect its performance, the ground cracked, and a series of issues that also affect other work smoothly and quality level. Floor heating system design should be rigorous serious computing and meticulous study. No professional floor heating design, that is, using the best heating products, high quality construction of heating of floor heating system is poor.

7. as long as the plumber one that can pavement heating

Many owners to lower initial investment, find a heating company designers do about design and decoration companies in accordance with the design drawings for plumber one that warm the construction, in fact, this is your irresponsible behavior, warm like heating just simple disassembly and Assembly, he needed to warm the construction personnel according to drawings for professional construction of floor heating. When heating to warm the pavement coil bending radians is too large, too small will affect the heating effect of the use, of a non-professional construction of heating construction personnel, warm paving results maywant to instead of, although there is a professional design, but no professional heating construction, it is a good product is also a pile of scrap metal, warm quality also cannot guarantee.

8. all you can do to warm houses

Due to the heating with energy-saving and comfortable features that many owners renovated House wanted to be warm, but not all of the House are suitable for floor heating, floor heating on the distribution of the pressure differential is has its own unique requirements, usually heat sink on the system requirements of the smaller, but warm on pressure requirements are relatively large, if without modification, it is easy to cause another user heating not hot. If you have problems with the pipeline pressure of residential heating, floor heating pipes made by pressure burst, so not only their own losses, but also compensation for the loss of the neighbor's House, in which case the loss is incalculable. So choose warm to the housing of the heating system of the nature of the choices.

Nine more dense, floor heating pipe, the better

In floor heating design time many owners are admitted to warm the coil, the more dense the better, the more the more dense, warm room, floor heating coil spacing of design is based on various factors in accordance with the relevant data with formulas make calculated, coil spacing is too tight, not only because of the indoor temperature is too high, causing dry heat can also affect human health.

High-quality heating system is a professional floor heating design, high-quality heating products, specifications of floor heating construction to complete, each link is to ensure quality. So when you choose warm from multiple angles, do not blindly choose. Only the right choice, go out to warm the misunderstanding, can guarantee the quality of floor heating.

【 Weak current College 】 the air conditioning with cooling technology law questions and answers 10---Power By 【 China power house network 】

101, the heat transfer coefficient of air-cooled condensers to (A) W/(m2.0C)
（A）23~35（B）1100（C）1200~1800（D）2000~3000
102, set condenser heat transfer coefficient up to (B) W/(m2.0C)
（A）23~35（B）1100（C）1200~1800（D）2000~3000
103, when the condenser inside or outside temperature up to (C) oC above the fusible plug melting, release the refrigerant.
（A）50（B）60（C）70（D）80
104, water-cooled condenser cooling water in and out of the way to (D)
(A) forward the following out (B) mobility on the (C) down into the following (D) into the upper out
105, medium and low pressure steel pressure vessel pressure test of the test pressure PT lower bound to (C)
（A）1.00P（B）1.05P（C）1.15P（D）1.25P
106, medium and low pressure steel pressure vessel test of hydraulic test pressure PT lower bound to (D)
（A）1.00P（B）1.05P（C）1.15P（D）1.25P
107, pressure container-gas tightness test pressure for (A)
（A）1.00P（B）1.05P（C）1.15P（D）1.25P
108, pressure vessel, there are four types of varieties, the most large and medium refrigeration system condenser belongs to (B)
(A) reaction pressure vessel (B) heat pressure vessel (C) separation of pressure vessel (D) storage of pressure vessels
109, refrigerant inside the condenser (C) (is.
(A) (B) too cold too hot (C) saturation (D) is not saturated
110, cooling water cooling the refrigerant condensers, condensing pressure (C)
(A) decrease (B) increase the (C) unchanged (D) 0
111, refrigerant saturation in the condenser, refrigerant dryness change to (B)
(A) the process of dry degree increase (B) the process of dry degree decrease (C) do not change processes (D) that it is not clear,
112, inner balance expansion valve diaphragm role with temperature sensor on the refrigerant pressure Pg, evaporation pressure Po and spring equivalent pressure Pw. When the three forces lose balance, pg. Po + Pw, valve for liquid measure (B)
(A) increase (B) (C) unchanged (D) that it is not clear
113, capillary usually uses the diameter of 200 mm (B) the pure copper tube production.
（A）0.3~0.5（B）0.5~2.5（C）2.5~5（D）3~6
114, ammonia filters using the mesh to (D) mm in 2 ~ 3-layer steel wire mesh.
（A）0.1（B）0.2（C）0.3（D）0.4
115, for liquid freon filters using the mesh to (A) mm copper wire net.
（A）0.1（B）0.2（C）0.3（D）0.4
116, used for filtering gas freon filters using the mesh to (B) mm copper wire net.
（A）0.1（B）0.2（C）0.3（D）0.4
117, expansion valve opening and evaporation temperature is (A)
(A) evaporation temperature high opening large (B) evaporation temperature high opening small
(C) evaporation temperature low open degree (D) after the opening set unchanged
118, refrigeration equipment, with the heat load changes, evaporator for fluid should be (A).
(A) increase the thermal load for volume increase (B) heat load reduction for volume increase
(C) increase the thermal load for fluid (D) the amount of heat load reduction for unchanged
119, throttle body comes in many forms, ammonia refrigeration system suitable for use (D).
(A) (B) by thermal expansion valves (C) thermal expansion valves (D) floating ball valve
120, throttle body comes in many forms, the appropriate unit air conditioner (B).
(A) (B) by thermal expansion valves (C) thermal expansion valves (D) floating ball valve
121, throttle body comes in many forms, household refrigerator appropriate (A).
(A) (B) by thermal expansion valves (C) thermal expansion valves (D) floating ball valve
122, the refrigerant to (D) for freon system, generally do not use a heat cycle.
（A）R12（B）R502（C）R113（D）R22
123, single-stage compressor maximum compression ratio should not exceed (C)
（A）5（B）6（C）8（D）10
124, single-stage freon compressor maximum compression ratio should not exceed (D)
（A）5（B）6（C）8（D）10
125,-vapour compression refrigeration system can only be reached by evaporating temperature (B) oC.
（（A）-30~-50（B）-20~-40（C）-10~-30（D）-10~-20
126. when condensation temperature 40oC, R717 single-stage compressors can achieve minimum evaporation temperature oC for (A).
（A）-19.5（B）-29.8（C）-31（D）-31.5
127, when condensation temperature 40oC, R12-stage compressor reach a minimum evaporation temperature (C) oC.
（A）-19.5（B）-29.8（C）-31（D）-31.5
128, when condensation temperature 40oC, R22-stage compressor reach a minimum evaporation temperatures (D) oC.
（A）-19.5（B）-29.8（C）-31（D）-31.5
129, when the condensation temperature 40oC, R717 levels compressors can achieve minimum evaporation temperature oC for (B).
（A）-60（B）-62.5（C）-66（D）-74
130. when condensation temperature 40oC, R12 levels compressors can achieve minimum evaporation temperature (C) oC.
（A）-60（B）-62.5（C）-66（D）-74
131, when condensation temperature 40oC, R22-stage compressor reach a minimum evaporation temperatures (D) oC.
（A）-60（B）-62.5（C）-66（D）-74
132, a two-stage compression refrigeration system to ()
(A) producing a lower temperature (B) reduce the power consumption of the compressor
(C) reference refrigerating factor (D) to reduce the cost of refrigeration equipment
133, get-low temperature 70oC following, generally use (D) of the refrigeration system.
(A) single-stage compression (B) (C) compression between three levels of compression (D)-complex overlap
134, two-stage compression system consisting of multiple overlapping refrigeration system available (A) oC of evaporation temperature.
（A）-70~-90（B）-75~-110（C）-120~-150（D）-150~-170
135, two-stage compression system consisting of multiple overlapping refrigeration system available (B) oC of evaporation temperature.
（A）-70~-90（B）-75~-110（C）-120~-150（D）-150~-170
136, ternary complex stack of refrigeration cycles available (C) oC of evaporation temperature.
（A）-70~-90（B）-75~-110（C）-120~-150（D）-150~-170
137, in order to obtain the evaporation temperature-100oC, (C) for the appropriate combination of complex duplication cycle.
(A) single-stage + R13R22 (B) single-stage or two-level R290 + R13-(C) R22 levels + R13-stage or two-level (D) R22 levels + R13 R14 single stage, single +
138, in order to obtain-140oC evaporation temperature, (D) to the appropriate combination of complex duplication cycle.
(A) single-stage + R13 R22 (B) single-stage or two-level R290 + R13-(C) R22 levels + R13-stage or two-level (D) R22 levels + R13 R14 single stage, single +
139, air conditioner air, the air temperature drops below the dew point temperature, air and moisture content (C)
(A) no changes (B) (C) (D) 0
140, use R22 of air-cooled air-conditioning in summer refrigeration debugging, the exhaust pressure is approximately (B) Mpa.
（A）2.4（B）1.9（C）1.5（D）1.2
141, in the refrigerator refrigerant in the refrigeration system, in the evaporator of the State can be thought of as (D)
(A) isobaric condensation (B) isothermal not isobaric (c) not isobaric condensation (D) isothermal isobaric
142, temperate type refrigerators use ambient temperature to (B).
（A）10~32（B）16~32（C）18~38（D）18`43
143, three-star refrigerator temperature (D) 0C
（A）0（B）-6（C）-12（D）-18
144, high and low temperature and low pressure test equipment used (D) early refrigeration, low investment, cooling, but the higher operating costs.
(A) piston refrigeration unit (B) screw chiller (C) air refrigeration units (D) expendable refrigerant
145, the following (A) not be used for low temperature test equipment of expendable refrigerant.
(A) R13 (B) of dry ice (C) liquid carbon dioxide (D) liquid ammonia
146, mechanical reefer interior temperature adjustable range (D) oC.
（A）10~-10（B）-15~-18（C）4~-20（D）12~-24
147, mechanical freezers keeps the temperature inside the car (B) oC.
（A）10~-10（B）-15~-18（C）4~-20（D）12~-24
148, offshore fishing vessel refrigeration system freezing temperature oC for (), refrigerated temperature 2oC.
（A）-24~-12（B）-18~-15（C）-15~-10（D）-12~-6
149, (C) has a small size, cooling capacity, energy can be adjusted.
(A) water cooled condensing unit (B) piston compressor condensing unit (C) screw compressor condensing unit (D) half-hermetic compressor condensing unit
150, centrifugal chillers with cooling capacity ranging from KW (D).
（A）50~180（B）10~1200（C）120~2200（D）350~35000

Weak current College】 【automatic escalator energy saving programmes on.

Escalators and passenger conveyors at hotels, Department stores, subway, train stations, Office, Club, airport and other places in the application more user-friendly and increasing the quality of service has played a very important role. But because of the particularity of their applications, part of the ladder is in idle state frequently, this will waste a lot of power, but also make ladder parts (such as the motor, gearbox, handrail, etc.) produce unnecessary wear and fatigue damage. At present the major escalator to hydraulic coupling speed or constant speed. But because the industrial field, use and maintenance of many problems, it is often necessary to maintain, low efficiency. Often, such as fault causing downtime-rotor, and even burnt motor. With power electronics and computer technology, AC motor frequency technology for reliable and durable, automation, control and feature-rich and so improves operating reliability and control precision, fully integrated protection, energy saving effect is good, simple control interface and rich, with computer communications interface, you can easily and microcomputer control system or process control systems, with the support of the software can be further upgraded to computer monitoring without the need for additional hardware investment. Current frequency conversion technology has been widely used in domestic metallurgy, coal, electricity, machinery, chemical industry, etc.
Operating principle
We know that, due to energy and electricity resources are scarce, the escalators in the unladen state running a huge waste. Therefore, we imagine, if you can let the escalator automatically detect idle state for a period of time, the directive escalator by speed reducer to half-speed operation. In access relatively frequently, based on the above thoughts, escalator detects idle state for a period of time, will be at full speed gradually slow down until you stop running to achievement of save power up to 30% to 50%. When the passengers on the escalator bed cover, ladder can be set in the bed cover entrance photoelectric sensing device auto-sensing passengers coming, start at full speed.
Automatic escalator energy saving case
1. reconstruction principles
In the normal use of no escalator have any negative impact of the introduction of sensorless vector inverter concepts. That is, converter according to the sensor signals, when someone take the escalator to the original design, speed; when no one ride, escalator slow down or stop running.
2. the role of the inverter
Main role is used to adjust the escalator speed, starting and running smoothly, without delay, after which the system automatically transferred to crawl operation, to achieve the purpose of energy saving. The escalator entrance install photoelectric switch, passengers photoelectric switch signals, ladder with variable speed-rated speed, when all passengers leaving escalator, escalator and automatically enter the low-speed operation status. Save energy, reduce mechanical wear, long life.
Transducer selection
System requirements for running a smooth start, no jitter, inverter starting torque, acceleration capability. KV2000 converter can provide adequate output torque and overload ability, speed adjustment and high precision, in open-loop velocity error can achieve < 0.5% torque response time short < 10ms.
Fully able to meet the requirements of the system.
Choose KV2000 sensorless vector inverter that can meet these requirements.
Electrical system
KV2000 sensorless vector converter is powerful, we take advantage of built-in features to TMIA system automatically detects, PLC's Refresh function, reduce the cost of acquisition and PLC programming workload.
When any one number KV2000 input terminals Xn is specified when TMIA function can select Y1 and Y2 or TA, TC, as the output function TMOA; plus contains timing (/count) module will constitute a delay disconnect relay. The duration of the delay by F071 decision.
When you enter TMIAON, output TMOA also immediately ON. But when after TMOA TMIAOFF must go through the definition of time F071 to OFF.
FWD
Y1
X1
COM
Signal detection
KV2000 Inverter control circuit
KV2000 contains timing (/count) functionality. When digital input terminals x 2 and 28 X4 selection mode, the timing (/count)-must be used at the counter using; or as a timer.
Fully automatic timing KV2000 converter features
System features
1, the speed of the wide, integrated energy-saving effect is good. Compared with traditional power save 10-30%.
2, a high degree of automation, application-rich and flexible. Strong object-oriented project programmability, depending on the size of the passenger traffic automatically adjust the motor speed.
3, reduce mechanical wear, reduced the amount of maintenance. Frequency converter with automatic soft-start function, reduces the start impulse current.
4. power capacity reduced escalator sometimes to multiple machines at the start, when the power supply capacity is insufficient to be considered when starting out in sequence. Use of frequency converters, low frequency (3HZ) starting, so even with the inverter capacity equivalent to more than one machine at the start, the starting current or inhibited. Therefore, power capacity can be considered by the inverter capacity. Compared with the use of frequency power, capacity can be reduced.
5. protection of the full-featured, secure, reliable, and durable.
With overvoltage, overcurrent, less voltage, overload, motor over-temperature, short circuit, phase, stalling (unique feature), automatic protection function and automatic retry transfer function, reduce unplanned outages and downtime. And automatically displays the cause of the failure.
6, technical data:
Overvoltage trip: 1.3Vmax
Undervoltage tripping: 0.65Vn
Start the transformationTorque: 200%, Tn
Overload capacity: 150% 1min
Motor stalling: programmable auto-tuning, adjustable
7, with nine group switch quantity input that can be used as start and stop, chain protection conditions special requirements of the control. A group of relay output, 4-ch transistor output can control chain protection, fault display, running, etc.
8, automatic optimization of electric current.
9, frequency set with manual and automatic.
10, converter comes with DC reactor, power can be increased to 0.98.
Escalators running characteristics of frequency
According to a supermarket is located in Shenzhen City of many foreign brands more than the escalator of frequency energy reliability test results of the validation of the technology innovation with powerful, workload, and other advantages.
1. no one staircase stairs automatically when: to ensure a smooth transition to energy efficiency, to 1/5 rated speed. (You can select when no one escalator, escalator auto stop function);
2. when someone by ladder: guarantee automatic escalator to energy speed smooth transition to the rated speed, the actual measurement is verified;
3, escalator no-load speed mode to energy saving, current only no-load rated speed run current of 1/3.
4. maintenance run-time: ladder system with 1/2 rated speed, ease of maintenance and observation of kinematic escalator, to avoid the original system rated speed to move the stop does not timely.
5, because no one staircase time and energy running speed is very low wear of mechanical parts, dramatically reducing the relative extension ladder of life.
6, the use of inverter technology significantly reduces the ladder starts on the power grid, adopt inverter can effectively improve the power grid of power factor, reduce reactive power consumption.
7, reconstruction takes into full consideration frequency conversion system and the system of coexistence, easy to switch between a system failure will not affect the user's use.
8, reconstruction borrowed the original system of security conditions, coupled with the inverter itself links allows modification of the system security and more reliable.
9, escalator energy saving equipment cost and energy savings and the cost of mechanical wear, inputs, and a payback within a short period of time, so the escalator safety improvement of frequency conversion technology development with successful, for improving the existing ladder safety and energy saving, has significant economic and social benefits.
Closing remarks
1, power save obvious: the escalator motor load is constant torque load, because no one escalator motor speed reduced to half the normal speed, so that power reduced to half.
2, reduce the wear due to the decline, the rotational speed of machinery parts wear significantly decreased and doubly reduced escalator maintenance costs.
3, safe and reliable: due to the use of KV2000 high performance frequency converter, in addition to motor protection, motor speed reduction due to a significant reduction in the motor temperature rise, the motor of a more secure and reliable.

【 Weak current College 】 summary of residential central air conditioning-Power By 【 China power house network 】

Household central air-conditioning can also be called residential central air conditioning, lighting and air conditioning, it is somewhere between the traditional central air conditioning and household room air conditioner in between a new field with the improvement of housing conditions and improve the quality of life and gradually developed a new wave of air conditioning. As people's living standards, gradually improve the quality of life, traditional room air conditioner although solves heat of comfort, but in some ways, but there are some disadvantages, especially for interior decorating requirements and taste improvement, air-conditioned comfort and air quality in the increasingly high demands. Decoration of funding increases, electricity expenditure relative decline and other factors, prompted the value between the central air conditioning and room air conditioner in two areas of domestic central air conditioning between came into being, gradually formed the current air-a new trend. Household central air-conditioning refrigeration capacity range generally in 7 ~ 80 kW or more, the available units of housing area 80 ~ 600 square meters, or even large villas apartments, duplex apartments, small office buildings etc. More household central air conditioning system combinations are available to a larger area with air conditioning. Household central air conditioning and central air conditioning and room air conditioner both advantages.　 Unlike traditional central air-conditioner compared to obviate the private room, at the same pipework and debugging easier.　 On the real estate developer, the air conditioning system does not have to first place, less investment, risk reduction, without losing the sale grades, household, that is, can fully enjoy the comfort of air conditioning, mobile and flexible, it is reasonable to assume the costs, but also in the interior design and layout to show when the air conditioner. Unlike traditional room air conditioner, some unitsmay be introduced into the fresh air, indoor air quality, from the "air conditioning sickness" troubles; can also be accessed via duct to the kitchen, the bathroom ventilation, indoor air distribution in a more rational, temperature fluctuations, comfort, good; use indoor ceiling decoration makes indoor unit easily placed in the ceiling, which does not affect the appearance of buildings, and the consequent security risks;　 may dispense with the traditional split-refrigerant connection hose will be exposed and hung in the indoor air of refinement. Household central air-conditioning, a small independent systems, energy consumption in large units and a traditional room air conditioner, between the refrigeration mode, the unit structure, processing the basic air methods and similar large central air conditioning, it is able to achieve harmony between architecture and air conditioner, comfort and appearance of coexistence. According to statistics, the United States has air conditioning family of about 72%, of which about residential central air conditioning 48%, window type air conditioners, split air conditioner accounted for 24%, i.e. approximately residential central air conditioning air-conditioning system of the United States Home 2/3. In recent years, China's domestic central air-conditioning showed good market prospects, open up a family "design, production, logistics, installation, service," brand new mode, realizes the air-conditioning use of "people-oriented, personality development."　 Household central air-conditioning as a new trend is emerging as the hot air development, domestic and foreign many manufacturers are developing and promoting their unit. The next two to three years, domestic central air-conditioning market share will reach approximately 8%. It is precisely because of the application of domestic central air-conditioning, a wider variety of its type, the name of our fledgling, crooner has not fully consolidated, it can be called residential central air conditioning, type of household central air conditioner, air conditioning, mini central air-conditioning, small air cooled chiller, air conditioning, air conditioning, indoor air-conditioned villas, a/c tetracarboxylic, frequency conversion multi-split, flexible centralized air conditioning and so on, its core is a small "conditioning"

Weak current College】 【heat pump ground heat exchangers review and improvement of heat transfer models --- Power By】 【China power house network.

Buried pipe ground source heat pump technology is currently the leading edge of air conditioning in the field of research. Buried pipe heat pump system with a high coefficient of performance, energy efficiency, renewable energy, environmental effects, the advantages of simple systems, in Europe and more widely applied, but in our country is still in its infancy, there are only very few underground pipe heat pump unit run successfully. China's vast, rich of surface layer (usually less than 400m) geothermal resources, therefore the effective use of shallow geothermal resources to overcome the traditional heat pump technology limitations and shortcomings, is very meaningful and practical value. Currently buried pipe heat pump is not like the rapid development of air-source heat pump that, in addition to the underground tube heat pump of high initial investments and to the requirements of rock and soil, do not exclude still lack reliable system design and simulation tools. Cane and calculation considers the current Forgas through North America's underground pipe heat pump works instance ground heat exchangers of the tube length is greater than the actual rate of 10% to 30% [1], which makes the short term recovery funds more impossible, is not conducive to the underground tube heat pump in the development and promotion.

Ground heat exchangers and rock steady-state heat transfer between right and wrong, and heat transfer in an infinite area, the process is very complicated, many influencing factors. From the existing literature, on the ground heat exchanger for heat transfer mechanism analysis focused on research and on the application stage, the soil body temperature field of study is based on heat conduction theory, consider groundwater movement of heat transfer and heat transfer mechanism, and so on very few, and domestic and foreign literature indicates the horizontal flow of groundwater on the soil body heat transfer processes have great impact [25]. Therefore, in order to understand how to set ground heat exchangers after the original characteristics of the underground environment, on heat conduction and groundwater movement of ground heat exchangers heat transfer mechanism is necessary for research.

1 ground heat exchangers of heat transfer models

Affect the buried pipe heat pump system performance factors are, including groundwater flow, backfill material performance, heat exchanger around the possibility of transformation, as well as along the length changes of physical properties of rock, and so on, how to improve ground heat exchangers-heat transfer model, make it a better simulation of ground heat exchangers of real heat situation, determine the best ground heat exchangers is the size of the development and promotion of underground pipe key ground source heat pumps.

Buried pipe system at present is still in the research phase, it has always been buried pipe heat pump technical difficulties, the existing underground pipe heat pump design methods are mostly based on a ground heat exchangers. Ground heat exchangers in general there are three forms, namely vertical buried, horizontal pipe and spiral pipe. Horizontal tube usually shallow burial, technical requirements, the initial investment is often less than the vertical buried; but because of the horizontal tube heat exchanger capacity is often less than the vertical buried, but laying area, excavation volume, sometimes it may not be the economy. According to the laying of differently, vertical buried usually has a u-tube and pipe two, and buried pipe heat pump project commonly used u-tube heat exchanger, although tube heat exchangers heat better than u-tube heat exchanger, but because of its initial investment, application there is very little, only used for shallow buried way.

Existing ground heat exchangers design software based primarily on line heat source theory, cylinder heat source theory [68], energy balance theory [915], establishing control equation. In the design of ground heat exchangers to consider long-running after ground heat exchangers, heat, heat imbalance caused by soil body temperature raise or lower the temperature of the analytical method for the ability to easily and quickly get long run results and personable, but if you consider the inlet and outlet water temperature, water flow rate, the geological layer and fill with affected analytics solution is difficult, therefore, you must make some necessary simplification, such as u-tube is equivalent to an equivalent single-tube to use column source theory, or as an infinite line heat source to use line heat source theory, etc. For long-running, these simplified little effect on the results, but for short run is not, this time using numerical solution more efficient. So there are some model considering the numerical and analytical methods.

Uses the parse method of calculation models mainly: Ingersoll model [1617], IGSHPA model [18], Hart and Couvillion model, Kavanaugh model [19] and Mei model [20], you can reference [21].

Design by numerical method to calculate the model mainly has following several. 1) Mei and Emerson heat transfer model and calculation methods [22]

Mei and Emerson developed an applicable to horizontal pipelines, considered around a mathematical model of permafrost. The mathematical model using finite difference method three one-dimensional PDE, describes around, tundra and distal region of the radiation heat transfer process. In addition, and on this basis, additional fluid along on tube length direction of one-dimensional heat transfer equation, a quasi two-dimensional model. The model for the wall, permafrost areas with different time step, for pipe fluid and non-permafrost areas with much more time step. Mei and Emerson provides analog values and 48d experimental values of comparison results.

2) Eskilson heat transfer model and calculation methods

Eskilson takes one dimensional a temperature response factor g function to simulate the underground tube heat exchangers of temperature field. The underground tube time varying thermal flow into the step function, then the step function together to strike the rock area of temperature field.

3) Nwwa (nationalwaterwellassociation) model and calculation methods

The model is in Kelvin line heat equation analysis solutions established on the basis of the soil layer, thereby determining the temperature field heat exchanger size. This method is also a kind of common ground heat exchangers calculation method, it can directly give the average within the heat exchanger and a temperature of fluidSuperposition method simulation of heat pump intermittent running [24].

4) Glhepro and Gchpcalc model

Glhepro model is in Sweden Lund University of heat transfer models based on analysis, may 1-year or multi-year to design vertical heat exchangers length. This heat transfer analysis is not only suitable for groundwater movement, there is no balance of thermal inhalation or release. While it is under design Gchpcalc model under the soil body heat absorbed or released to calculate the length of the heat exchanger [25].

5) Muraya model and calculation methods [25]

Muraya use a dynamic, two-dimensional finite element model of U-tube feet hot interference problems between. The model by trying to define heat exchanger efficiency, based on the soil body composition and backfill soil characteristics, 2-pin spacing, distal and tube temperature and the thermal diffusivity to quantify this type of interference problems. The model has been used constant heat flux, temperature two conditions of heat source theory analysis method of authentication. Using this model, you can calculate depending on tube geometry of synthetic heat transfer efficiency and impact of backfill.