【 Weak current College 】 chillers mainly parts maintenance

1. maintenance of the chiller compressors
(1) Visual inspection of the compressor
Checking method: Visual
Check criteria: check chiller compressors and export valve connection reliability, and whether there is a leak; testing should be aware of the compressor running voice to determine whether there is an exception.

(2) the voltage and current measurement
Measure tool: clip-on ammeter
With clip-on ammeter working voltage, current. When running the current measuring cables should be in the Centre of the measuring loop metrics: 380V running voltage range (± 10%), and run-current should not be greater than the motor nameplate of rated input current.

(3) measurement of insulation resistance
Measure tool: megohmmeter
Measurement method: power off the unit, with three megohmmeter detection compressor relatively resistance meets the standards. If the machine head of time is not enabled, you should first be set in the crankcase electric heating cycle
Still, oil heating unit, the unit oil cavity of freon evaporation, improve the accuracy of the measurement of resistance.
Measurements Note: no measurement under the vacuum State, prevent the insulating layer of insulation breakdown caused by the accident.
Measurement standards: compressor motor insulation standards for not less than 500 MB, the actual measurement value should be greater than 100 megohm is qualified, under the hot and cold insulation value is greater than 8 megohm is allowed to run.

(4) the method for the determination of the oil products:
Available from the chiller unit to extract the oil in a small frozen into the container, take a drop into acid reagent bottle observation of acidity, with a contrast ratio of color card. Consistent with a controlled than color card colors should not be replaced refrigeration oil.
Extract from the unit in a little frozen oil into the container, to minimize the exposure time in the air, and then use the PH test strip discriminant oil acidity. Comply with the requirements of oleic acid degree does not need to be replaced refrigeration oil, used oil blotting paper checks of impurity, carbon emission, or other impurities and should be replaced refrigeration oil.

2. maintenance of condenser
Maintenance tool: pipeline cleaning machine or chemical cleaning agents.
Maintenance: water cooled condenser with shell and tube water-cooled condenser, condenser cleaning and maintenance work
As very important, good cooling water quality should be maintained, cooling water chemical treatment should be conducted on a regular basis to ensure heat transfer tubes not scaling, maintenance can be divided into mechanical cleaning and chemical cleaning (refer to chemical cleaning procedures).
Mechanical cleaning methods:

1. shut down the cooling water and export the valve
2. detach the condenser and rear end cover
3. clean the condenser end cover, water Chamber cavity scaling and corrosion
4. pipe cleaner cleaning heat pipe
5. after washing with water, until you reach the standard, and then put the end cover
Maintenance standards: maintenance after water room, the overall heat transfer tubes visually clean, no apparent scaling wall

Notes: 1. what methods of cleaning, according to the condenser tube forms to identify and prevent damage to the Inner ribbed tube
2. uniform chemical cleaning must
3. the concentration of detergent and cleaning time to follow the manufacturer instructions for
4. rinse time must be clean, completely, without residue

3. maintenance of the evaporator
(1) check the frozen water and evaporator scaling, do a good sewage water exchanger
(2) detection of water side and refrigerant temperature difference between
(3) maintenance should open the evaporator bottom of sewage valve will impurities, sludge discharge. If necessary, remove the sewage valve, to increase the outfall
(4) in particular it should be noted that during the winter does not use water to prevent freezing damage caused evaporator
(5) to prevent dropping out of the sensor shall lead to induction of temperature is the temperature of the air instead of evaporator temperature, resulting in frequent low temperature alarm
(6) maintenance work can reference when sewage, the following steps:
1. run the water pumps in 10 minutes
2. in a outlet check water quality
3. According to the color of water, suspended solids, rust, etc., we recommend that users use mechanical cleaning or chemical cleaning
4. after cleaning, sewage valve open to most, sewage
5. row of net again pouring water, running for 30 minutes and then view a water, if necessary, then the job once

4. Unit piping and fittings maintenance
4.1 expansion valve of checking
Testing tools: surface contact thermometer
Checking method: check the expansion valve Junction has no traces according to overheat, compressor unit back to the gas side condensation level determines the unit run time expansion valve opening is appropriate, check that the sensor is loose, bundled with position sensor of the capillary is no wear and tear. On balance pipe connection nut, bolt do antirust protection valve.
4.2 as liquid mirror checks and drying filter replacement
Check tool: surface contact thermometer
Checking method: Visual inspection as liquid mirror display cases in the test strip judge system refrigerant of humidity, confirm the need to replace dry filter, surface contact thermometers for measuring the temperature difference is lower than before and after the filter, that filter clean 0.5 ℃.
Drying filter replacement method:
1. first close the high-pressure fluid, moving units exported angle valve and pumping systems for low-voltage side of the refrigerant (non-vacuum suction), and then locking unit
2. detection of drying filter pressure is lower than the adjacent 2.0kg/c © o, if you add refrigerant pipes to the parts of the emissions of gaseous refrigerant
3. diagonal release of drying filter end cap screws (release note difference before to prevent temperature difference of water into the system), emptying refrigerant then quickly change the old filter, clean and dry the filter cylinder internal, get a new filter, add a small cylinder of port sealed refrigeration oil.
4. vacuum supplement a little refrigerant, open front closed valve
Maintenance standards: sight glass indicates in a dry area is less than the difference before and after the dryer 0.5℃
4.3 electrical components maintenance
Testing tools: Multimeters and selection of ampere meter
Maintenance method:

1. check and fastening electric line terminal, check the contactor contacts of burning conditions
2. the contact points with canvas and grinding to remove oxide, if severe, it is recommended that you replace the burns
3. check if the solenoid valve, such as 4-way reversing valve, solenoid valve, the unit loading and unloading of solenoid valve, solenoid valve for spraying liquid, electric heating and other actions properly, or to replace or repair.
Maintenance standards: contact clean, no Burns oxides, Sync contact, non-ripple noise.
4.4 check all safety devices
Maintenance methods: inspection and testing of all security devices (thermal protector, flow switch, pressure switches, and other protection devices), check the tuning parameters
Maintenance standards: thermal protection with good retention, wiring intact, flow switch, open and close motion normal, high and low voltage switch action in 24.5 ± 0.5Bar.

【 Weak current College 】 elevator electrical failure lookup method

When the elevator control circuit failure, the first question to ask, see, hear, smell, be aware of. The so-called asked, is asking the actor or report the failure of failure occurs, the query failure before doing any adjustment or replacement components; the so-called, is the observation of each part is working properly, take control of various signal indicates that the elevator is correct, see electrical components appearance color is changed. "Listen, listen circuit work when abnormal sound; sounds that smell that smell circuit elements whether there are abnormal odour. Upon completion of the work, you can use the following methods to find electrical control circuit failure.

1, the program checks the method

Elevator is a program to run every time you run all through the selected layer, directional, closed, start, run, change speed, leveling, opening the door of the cycle, where each step is called a working link for each work session, there is a corresponding control circuit. Program inspection method is to confirm that the failure of specific control links appearing on which, in the direction of the troubleshooting change clear, targeted is very important for troubleshooting. This method applies not only to have contact with electrical control devices, also applies to the contactless control system, such as the PC control system or microprocessor control system.

2. static resistance measurement method

Static resistance method variable is in power, multimeter resistance measurement circuit resistance stalls are normal, because any one of the electronic components are a PN structure, its forward and backward resistance values are different, no electrical components also have a certain resistance, connected to the electrical components of the line or switch, resistor value not equal to zero is infinity, measuring their resistance value size compliance requirements can judge. Check an electronic circuits are available with and without fault, but this method is more secure.

3. potential measurement method

The above method failed parts cannot be determined, in each case measuring power electronic or electrical components devices at both ends of the potential, because under normal working conditions, current-loop circuit points potential is considerable, the so-called points potential refers to various points on the circuit components on the potentials of different, but have a certain size requirements, current flows from the high potential, low-voltage current direction measurement of electronic and electrical components on the potential size should be consistent with the law, through the multimeter measurement control circuit for points of potential compliance values, you can determine where the point of failure, and then determine what caused the current value of the change, is the power supply is not correct, or the circuit-breakers, or component is damaged.

4 short circuit method

Control-link circuit by a switch or a relay, contactor contacts a combination. When you suspect that some contact is at fault, it is possible to use wire to the contact shorted, power to prove fault disappears, the judgement, the electrical components is bad. But remember, as a test after the point of failure should be removed immediately after short wiring, wiring with short is not permitted in place of the switch or contact. Short-circuit method is mainly used to find the electric circuit of breakpoint logical relationships, of course, sometimes the measurement circuit faults can also use this method.

5. circuit breaker method

Control circuit also may be some special failure, such as the elevator does not have internal or external call indicates when it stops, etc. This shows that some contact is in circuit shorted, find such a failure is the best way is the circuit breaker method, it is suspected that the contact points generated fault, if fault breaks away, explains the correct judgment, circuit breaker method is used primarily for "and" logical relationship point of failure.

6. substitution method

In the light of the above methods, found fault for a point or a block circuit board, you can take that component or circuit board removed, use new or confirm no failure of a component or circuit board in place, if the failure is considered to determine the right away. Instead you need to continue to find, often maintenance personnel on the vulnerability of the components or important electronic boards are available in spare parts, once there is a failure immediately put on a piece that solves the problem, faulty parts back then slowly find repair, it is also a quick troubleshooting method.

7. experience of elimination

In order to be able to achieve rapid troubleshooting, in addition to constantly sum up their own practical experiences, to learn the experience of others. Elevator malfunction formation there is a certain law, experience with sweat and lessons of, we should pay more attention to these experience allows us to quickly troubleshoot and reduce accidents and losses. Of course, strictly speaking it should eliminate the elevator accident, this is our application maintenance personnel. Learning with our maintenance and troubleshooting experience, you can increase the lift installation maintenance staff skill levels, improve the quality of service elevator industry and credibility.

8. electrical system troubleshooting basic ideas

Electrical control system sometimes fault is more complex, there are currently in the elevator with many uses computer-controlled, cross-hardware and software together, experiencing trouble first thoughts don't be nervous, troubleshooting difficult ones later, when adhering to the first-in, after consideration, an association.

Elevator in more failure is caused by poor contact switch contact, so judgment fails should be based on the fault and the led display control cabinet, the first external lines, power part inspection, first check the door contact, safety circuits, AC-DC power supplies, etc., as long as you are familiar with the circuit, this allows you to solve very quickly.

Some faults are not as relay line so simple and intuitive, the protection of many PC elevator is implicit in its software, hardware, system, its failures and reason as results and conditions is strictly correspond to find fault in an orderly manner on their relationship with Lenovo and forecast, to exclude questions one by one until the fault completely ruled out.

【 Weak current College 】 solar thermal engineering components and principles – Power By 【 China power house network 】

Solar central heating system is made up of collectors, thermal water, control system, automatic water control box, circulation pump, pipe fittings and other organic combination of heat supply system. It is made up of collectors absorb solar radiation into heat, cold water into hot water; water by automatic control box automatically on the water, and by adjusting the control system achieves: temperature cycle — improve the thermal efficiency; pipeline cycle set — open the faucet that is out of hot water; timing fixed temperature electric heating measures — constant hot water supply; water supply; 24 hour temperature (≤ 0 constant pressure water supply. 6Mpa); antifreeze device — winter as usual. The entire system automatically run, using a secure, easy to maintain. Composite structure, according to the consumption of water, the installation site, the user needs for flexible permutations and combinations. Electrical insulation tank is equipped with a heating device, according to user needs and actual condition, electrical heating power can increase or decrease as appropriate to meet the wet weather and winter with the hot water requirements, achieve photoelectric complementary, microcomputer intelligent control, ensure 24 x 7 x 365 supply plenty of hot water. Solar energy engineering knowledge product selection: as engineering products, not only on product quality have higher requirements, while in the product design or to comply with engineering product requirements. You cannot use the generic product in engineering design, because the market retail products for family use, if the design used in project failure rate is high, the thermal efficiency is low, the design intent. Piping design: design engineering joins the tubing is of particular importance, if the system piping design not prone to water resistance is too big, small, hot water production, supply, sometimes there may be problems such as hot water circuit. Severely affected the normal operation of the system, the pipeline design as possible requires water balance, pipe diameter requirements and system design to match the calculation pipeline reasonable traffic. Secondary energy: solar collector is relying on rain-fed, if encountered rain fog snow weather solar illumination is insufficient, the collector could not get enough energy, solar energy project does not meet the requirements of normal water, then second energy as secondary. Select engineering General solar electric heating, electric boiler, gas boilers, boiler and auxiliary energy devices, device model selection taking into account the maximum rain fog and snow, the hot water demand will avoid affecting normal hot water requirements while achieving economic rationality of the investment. Control system: electric control is an important part of the solar project, it can implement hot water project of intelligent control, such as: automatic water, water full stop, the temperature of the water level display, automatic or scheduled timing electric heating, water and pipeline cycle and the supercharger, etc. Control system selection are particularly important because electric has some instability, high failure rate, need special maintenance. Control system requires formal manufacturers for production, this is a system of quality assurance. Reduce system failure rate, improve the overall performance of the solar project. Water system: solar projects to provide a constant hot water, this would need to have enough water. Generally use the float box as water tools, floating ball box can play a role on the current-limiting solar projects water stable, safe and reliable. In the Northern cold season, you need to make to the float tank insulation necessary increase in internal, guarantee electrical heating in cold water to replenish, does not affect the normal system operation. Solar energy engineering FAQ before you understand, design problems: 1, unit of building conditions: building collector area size, shape,building height and position of allowing tanks (roof, floor, the basement, etc.) are not the same without the same. 2. user requirements: the total amount of daily water use; the user is a daily scheduled once used or ready for use; water temperature; water use; practical use: the bath water, pool heating, pool heating, environment (cultivation or farmed greenhouse) heating. COM 3, geographic location and conditions: according to the user's geographic latitude and winter minimum ambient temperature conditions, four seasons sunshine, Chaoyang direction for Eclipse, analysis of installation conditions. 4. user auxiliary energy conditions: determine the (electric heater, electric boiler, oil, gas boilers, water, land or air-source heat pump, etc.) a program or a combination of the two above. 5 user units of water pressure and voltage: understanding user units of water pressure and voltage and supply. Second, the common design 1, household solar water heater series-parallel programmes. When the user requests are not very high in the case of the more common, suitable for the user conditions relatively simple environment. The installation number then the load is too heavy, for buildings of any adverse impact. Design note on launching the diameter of the charge of road and series-parallel relationship, avoid water supply and water consumption have contradictions. 2. natural circulation design. In the small tonnage is also very widespread in water consumption, water consumption is not suitable for large tonnage. This approach is quite simple, have certain requirements, water tanks and solar collectors, water tanks on the height of the frame you want to calculate the loads and windproof, consistent with the steel structure design code, regardless of what mode of solar collector, the number of series-parallel requires reasonable, consistent with the solar hot water system design, installation and engineering acceptance specification. 3. constant temperature water design. By collectors and tank temperature difference between the control into the cold water will reach the temperature of hot water into the tank top, water tank of hot water with the temperature cycle to continue after the adoption of increased temperature, which is a lot of solar companies currently use. This way when the sunlight conditions generally do not have problems, poor conditions in the sunshine, you should note in this scenario, the timely fill water tank should have a certain amount of water to prevent ganshao electric heater. When the water temperature of the water tank below the set temperature, the required secondary energy equipment in a timely manner, ensuring the user's normal use. In addition, in the design according to user requirements, respectively set either daily scheduled heating method and constant temperature heating mode at any time. In the North have low anti-freeze protection. 4. temperature cycle design. Through the controller settings, make a tank filled with water, the highest level, the use of solar collectors and tank temperature, controlled circulation pump work, unceasingly toL water tank, water temperature in, this is a very practical difference in cycle programmes. Design according to the different uses of water use and water temperature. Daily scheduled on the water, when the minimum water level, automatic water at any time, and ensure a certain amount of water in the tank. According to user requirements, the auxiliary energy equipment can take one or two above. Design according to the needs of users, you can set a daily scheduled heating or fixed temperature heating mode at any time. Requirements in the north low anti-freeze protection.
Third, the controller features and system design: 1, tank temperature display: you can watch the water temperature in the tank, this is the user use frequently need to know about solar system work of important data collector temperature display: you can always watch collectors in the main,this is the system debugging needs to know about solar system work in one of the important factors. 3. water level status display: display with five-level water level, water level status at a glance. This is also a frequent user of important data. 4, regular heating time: set the heating time every day, the controller in reset time under water temperature determine the need to automatically start the heating function. 5. set the heating temperature: setting the scope of the applicable to different user requirements, bath temperature is generally 30 ℃-75 ¡æ is appropriate, in accordance with the requirements set for other purposes, you can set a maximum 99 ℃. 6. set the heating mode: uses regular heating or constant heating. Regular heating is in the set time, daily heating to set the temperature; temperature heating is in the water temperature is lower than the set temperature on certain values and heating of water at any time, to set the temperature when you stop the heating. 7. set the time setting on the water every day on the water time controller in reset time makes the water level to automatically start the Sheung Shui to the highest level only, using solenoid valve or pump can be determined. 8, low water level automatic water: when the water level drops to lowest level, the controller should unconditionally automatic water, ensuring water tank there is plenty of water. 9, water temperature control: the water tank of water temperature according to the purpose to set, bath temperature, greenhouse heating temperature, material drying temperature different needs, the set temperature. Winterizing 10, System: in addition to note the thickness of the insulation material, you can use pipeline emptying method; you can also use the system-wide recycling method or both heating cable protection, when the system temperature reaches the temperature range, you can use the various methods for systematic antifreeze protection. 11, remote monitoring: there are some users need in a location other than the control room needs to understand the solar system is working properly, when the controller work will detect a failure. 12, use hot water temperature cycle: with the use of hot water circulation function, you can make the hot water circulation line always remains with the storage water tank temperature close or identical to the user in any faucet is opened, the hot water to make the user's ease of use with hot water. 13, increase the heating function: according to the set temperature in heating met South and the north part of the heating requirements, production activities (vegetables, flowers, greenhouse) part of the warming and drying room, part of the General energy savings. 14, electrical control cabinet: control cabinet incircuit total controller and tap controller, note the use of power matching of fuses, circuit breakers, earth leakage protection device, relays and AC contactor, when a short circuit or power supply equipment, the total leakage phenomenon and the road divided the controller controller promptly cut off circuit, identify the cause of the failure before recovery. Temperature controllers and electrical control should be installed correctly, you must connect the protective earth. 15. installation forms: according to environmental criteria, you can use a variety of angles, with forced circulation patterns can be from 0 degrees to 90 degrees any installation run. 16, energy storage insulation water tank: appropriate SMC glass assembled insulation tanks or stainless steel modular water tank. The second tank features: clean sanitation, never rusts, in accordance with hygienic standards, light weight, structure reasonable, on-site assembly sites demand is low. Tank design life are in 30 years. External tank with high-performance materials for insulation and protection. 17, lightning protection measures: solar system bodies for metal structures, steel structures and building original lightning system connection, you can effectively prevent lightning strikes. 18, windproof: solar system of steel angle brackets with Slipknot or welding together, collector supports use of angle steel and roof connection or a connection to a fixed location should be consistent with the steel structure design code, to wind effects.

【 Weak current College 】 domestic IC card meter status and development trend

IC card water meter has been 10 years old. 10 years, IC card meter has undergone rapid improvement from scratch, and gradually mature. At present, the Chinese have full intellectual property rights of metering and settlement product development can be said to have reached a relatively complete, basic practical phase, as all kinds of smart metering instruments the most mature in technology, market development the most widely used, installed, the simplest and most convenient a product. Its technical capabilities and functional characteristics and the vast majority of regional economic development level of adaptation, one of the other types of smart metering instruments that cannot be compared. Therefore, when other types of smart metering instruments also discuss the pros and cons of the various programmes, IC card meter has a huge user community.

A, and other types of smart metering instruments, IC card meter of advantages and disadvantages

At present, various types of smart metering instruments in the market for beauty. Division of information transmission, can generally be divided into remote meter, IC card meter and code meter. Code meter, information transmission in the original, action, general user not cumbersome does not classify smart metering instruments, this article does not make the comparison.

Large, IC card meter has four distinct advantages are other other types of smart metering instruments that cannot be replaced by:

1. direct user transparency. How much water is used, how many charges deducted, users want to see when they come to see, want to see how long it will take depends on how long the transparency achieved satisfaction makes direct users to feel at ease.
2, direct users to engage in sex. When paying, the number of charges, the initiative has a direct users. No longer is detained for many fastening, the managing departments; early hand cannot, late submission fails completely passive situation.
3. installation of convenience. It's not like the dedicated remote meter needs through wall wiring hole, and you don't have to like a wireless remote metering table requires repeated adjustment concentrator locations, or like a low-voltage power line carrier transmission meter like Powerline lead connections. Basically connected line or lines can be used after.
4. real-time settlement, particularly in available price ladder (or time-of-use pricing, time-of-gas price, etc.) in real time.

On management departments and managers have a deep-seated distrust of direct users, use the machine measurement, machine clearing, holding the card to pay, how much, how many are not subject to management and management control, this is a way of change, is the psychological release, the IC card meter to direct users to the use of value.

IC card meter also has the following to be ignored for birth defects:

1. data feedback is not timely, management cannot use water data in real time statistics.
2. data transmission automation, networking of not enough.

IC card meter of advantages and drawbacks, determines its market orientation and improvement of direction.

Second, the current product status

Overall, the current IC card meter in the entire industry has essentially solved the valve reliability, durability, battery low power circuit design and anti-jamming design consistency issues, trends and the value of products began. Product features are very similar, the gradual convergence. The competition between manufacturers of products, research and development components, production organization, management and quality control of components. The pros and cons of the product quality and stability of the competition, has started production of size, level of modernization of production and management methods of the advanced nature and effectiveness of the decision. This is the sign of the maturing industry.

This maturation is an ever-closer to the goal, much remains to be done. There are three main areas:

1, to really solve the IC card meter of reliability and durability issues;
2. in order to solve data security and data interface standardization;
3, to try to solve data feedback real-time and network problems.

About IC card meter reliability and durability issues, expressed in the first, the complete machine failure rate remains high, the average time between failures (MTBF) less to achieve 5 x 104, unsatisfactory. Second, product batch consistency and coherence of industry can meet advanced standard, quality control costs. Important reason is that many of the parts, components need improvement and innovation.

1, valve. Valve is a key part of IC card meter is long inhibited the development of IC card meter. Domestic IC card meter valve from pilot valve development to electric ball valve and electric ceramic valve, it is now practical problems initially solved. But the required control of energy and power supply still does not match, their long-term stability and reliability are improved and innovative space.
2, power. Power is also the key IC card meter is restricting the part of IC card meter development of bottlenecks. IC card meter now widespread use of the power supply is typically disposable batteries, lithium-battery. This type of battery performance of small current discharge and driven electric ball valve or electric ceramic valve required large current contradictions between. General reconcile method is to activate the battery regularly, keep it can produce high-current status. But the activation energy consumption will shorten battery life. Furthermore, the battery lifetime of late is activated or activation mode is the same with the earlier stage, there are many uncertain factors. Resolving power durability and reliability issues, and to resolve environmental problems, is the power supply IC card meter industry must face an important topic.
3, the base table. Current IC card meter measurement part, remains the traditional speed mechanical water meters. In terms of cost control was very demanding, this is certainly a better able to accept the solution. However, this kind of measurement part accuracy and life, and IC card can not be compared to other parts of water meters. Now the IC card meter and previous mechanical and electrical integration of IC card electricity meters, should only be a yield to the prevailing market and costs of transition. Development of long-life high accuracy, or base tables and long-life high accuracy of full-electronic IC card meter, must surely be the IC card water meters in the direction of the industry.
4. sampling method. Now IC card meter popular picks-Like manner, is still a Reed pipe and Hall devices, known as a magnetic sampling. Cheap, low power consumption, long life, simple, reliable is it to the root causes of the epidemic. Vulnerable to an attack; and measurement of the magnetic base interaction force is big, the launching in flow, base effects is their common shortcomings. Development is not affected by magnetic attacks, and measurement of the base table without forcing or force is small, the effect on the base table Holter monitoring flow ignored and cheap, low power consumption, long life, reliable sampling is a practitioner.

Data security and data interface standardization problem water meter, IC card has not been adequate attention in the industry that the current IC card meter market only to follow the IC card cold water meter "standards, at the expense of data security and data interface standard. Different manufacturers of products that are incompatible with each other, cannot substitute for each other; data security measures and prohibitions, you cannot test, no supervision; product features varied, not common management platform. These are industry is not very mature support, also affect the industry further obstacles to development.

Real-time data feedback and networking is incomplete, the IC card meter 2 structural defects. From the perspective of information transmission, IC card is information carriers, IC card in management information systems and the table with the movement between information constitute an artificial channel. Because of this artificial channel arbitrary and not controllable, causing the two defects. IC card meter industry only face problems, propose solutions to overcome the defects, to open up a broader market. Ostrich policy has no way out. Currently, manufacturers to address this issue than a certain number of attempts. But because of unclear significance testing, plus the pilot scale sufficient to attract attention, show enough, so the effect is not noticeable, not much impact.

Third, the development direction

1, IC card meter represents a management mode. This management model makes management and user interaction, to mobility between user involvement in the management of the initiative, conducive to the rational use of water resources and conservation of water resources. Its advantages are the other management methods (such as remote water meter) is not simple to achieve, and China's economic development and social psychology. IC card meter will continue to rapidly to the advanced stage of development.
2. gradually unified security level. Unified data interface, unified basic functionality, unified transaction process, is an inevitable development of IC card meter. It can be said that the water meter current IC card industry only preliminary reached the usefulness of the device hardware, hardware will continue to improve and innovate software more to engage the specifications and compatibility, a long way to go. Data security, data interfaces, complete with a card transaction process and basic features of reunification, already proposed. At present there are a certain number of requirements in accordance with four integrated manufacturing of CPU card meter is running. Whether from a manufacturing perspective or from the use of perspective, the IC card meter are initially shown vitality. Manufacturers and users from the original on the manufacturing cost concerns, along with SAM module and CPU card costs progressively reduced. Statistics show that this kind of table failure rate and low maintenance, saving the cost of the service may be part of the increase in raw material cost compensation.
3, in the IC card meter data remote install, implement the interface information real-time feedback to enable data transfer automation and networking. Real-time data transfer requires not only the management must also be information society on basic management information sources must, IC Card Designer and producer of the meter cannot and will not shy away from. Therefore, adding data remote transmission interface, increased data remote transmission function is to enhance the vitality of IC card meter, and expand the market share of improvement.

IC card settlement and basic management data remote transmission combination of style, you can have the figures 1 and 2.

Figure 1 shows the system is an IC card settlement and basic management data remote transmission two features of superposition system, product cost IC card meter slightly increased, but the system functioning is not affected by the communication lines (channel), interference or failure, and more reliable.

Figure 2 shows the system is an IC card settlement and basic management data remote transmission two features of the organic integration of concentrator all table with sharing a set of IC card read-write unit and display unit, resulting in a lower-cost, high performance-price ratio, but the system functioning vulnerable communication lines (channel), interference or failure.

【 Weak current College 】 compressor failure analysis---motor burnt

Compressor failure analysis (1) motor burnt
Motor compressor (hereinafter referred to as compressor) can be divided into motor fault and mechanical failures (including the crankshaft, connecting rod, Pistons, valve, cylinder head gaskets, etc.). Mechanical failure often make motor overload or stalling, is motor one of the main causes of damage.

Motor damage mainly manifested in the stator winding insulation damage (short circuit) and circuit breakers, etc. Stator winding damage after difficult was found, in a timely manner may result in the winding burned down eventually. Winding burned, cover some of the causes of the phenomenon or burn directly causes, making the subsequent analysis and cause investigation difficult.

However, motor functioning without the normal power supply input, reasonable motor load, good heat dissipation and winding wire insulating layer of protection. Starting from these areas, it is not difficult to discover winding burned down six reasons as follows: (1) abnormal load and no-load; (2) scrap metal winding caused; (3) contactor issues; (4) power phase and voltage anomalies; (5) insufficient cooling; (6) vacuum with a compressor. In fact, a variety of factors contributed to the more common electrical damage.

1, abnormal load and no-load

Motor load including the required load compressed gases and overcome friction the desired load. Compression ratio is too large, or pressure differential is too large to cause the compression process more difficult; but lubrication failure caused by friction resistance increase, as well as the extreme case of motor stalling, will significantly increase the motor load.

Lubrication failure, the friction resistance increase, is the leading cause of load exception. Back to liquid diluted oil, lubricating oil, oil heat, coking and lack of oil deterioration, etc will disrupt normal lubrication, cause lubrication failure. Back to the dilution effect of lubricating oil, friction surface normal oil film formation, even washed away the original film, increase friction and wear. Compressor overheating will cause the lube oil temperature thinned even coking, impacting oil film formation. System back to oil is not good, compressor oil shortage, nature cannot maintain normal lubrication. Crankshaft rotation speed, such as high-speed movement of the piston rod, no oil film protection of friction surface will rapidly heating up, local temperature enables the rapid evaporation of lubricating oil or coking, the more difficult parts lubrication, seconds can cause local severe wear. Lubrication failure, local wear, so that the crankshaft rotation needs greater torque. Small power compressor (such as fridge, air-conditioner compressor) because the motor torque, lubrication failure often appear after stalling (motor not running), and enter "stalling-heat protection-stalling" death cycle, motor burned it's just a matter of time. And high-power semi-enclosed compressor Motors torques are large, local and wear does not cause stalling, motor power in a certain range as the load increases, thus causing more serious wear, even bite cylinder (cylinder piston card in), Rod fracture, and other severe damage.

No-load current (locked rotor current) about normal operation current of 4-8 times. Motor start instant, current peak can be close to or reach locked-rotor current. Due to resistance on heat and proportional to the square of the current, starting and locked rotor current when the rapid warming will make winding. Heat protection can protect electrode-rotor, but normally does have a very quick response, it will not prevent frequent start caused by winding temperature changes. Frequent start and abnormal load, winding through high-temperature test, reduces wire insulation performance.

In addition, compressed gas required load will also increase the compression ratio and the pressure difference grows. Therefore the high temperature compressor forlow temperature, low temperature or high temperature, the compressor is used to affect the motor load and heat, is not appropriate, will shorten the service life of the electrodes.

Winding insulation performance variation, if there are other factors (such as scrap metal or conductive circuit, acidic form lubricants, etc.), it is easy to cause a short circuit and damage.

2, scrap metal or caused by short circuit

Winding of scrap metal in the inclusions are short circuit and grounding insulation value low. Compressor running time of normal vibration, as well as the start winding affected by electromagnetic force and twisting will promote inclusion, in the windings of scrap metal and winding wire relative movement and friction. Sharp metal edges will scratch the enameled wire insulation, causing a short circuit.

Scrap metal construction of sources including left of copper tube cutting, welding slag, compressor damage internal wear and spare parts (such as a valve plate broken) fall under sweepings, etc. For hermetic compressor (including hermetic scroll compressor), these metal shavings or broken grains will fall on the winding. For semi-hermetic compressors, some particles with gas and oil flow in the system, and finally because magnetic gathered in winding; and some scrap metal (for example, bearing wear and abrasion motor rotor and stator (scrapping) of) directly on the winding. Winding and gathered in the scrap metal, short circuit is only a matter of time.

In need of special attention of the two-stage compressor. In two-stage compressor, back to the gas and normal return oil directly into the first level (low level) cylinder, compressed with medium pressure pipe enter Motors Chamber cooling coil, single-stage compressor and then, enter the second level (high grade cylinders). Back to the gas with lubricating oil, has made the compression process in perpetuity, if further back into the liquid, the first cylinder valve slice can easily be broken. Broken valve plate with medium pressure pipe after entering the windings. Therefore, the two-stage compressor than single-stage compressors are more prone to scrap metal causing the motor circuit.

Unfortunate things conspired to one, the problem is in the power of the compressor of the Messenger from the often lubricant jiaohu flavor. Metal face serious wear and temperature is very high, and lubricants in 175oC above start cooking. System if there is more moisture (vacuum pump was not ideal, lubricants and refrigerants moisture, negative pressure return gas pipe rupture after air, etc.), lubricating oil acidity may occur. Acidic corrosion Lube will copper pipe and winding insulation, on the one hand, it will cause the copper plating; on the other hand, this contains copper atoms acid oil insulation performance is poor for winding.

Issue 3, contactors

ContactIs a motor control circuit in one of the important parts, selection of unreasonable can damage the best compressor. Press the load correctly select the contactor is extremely important.

Contact device must be able to meet the demanding conditions, such as rapid cycling, sustained overload and low voltage. They must be sufficiently large area to distribute load currents generated by the heat, contact materials selection must start or stalling, etc. larger current circumstances can prevent bonding.

In order to secure and reliable, the compressor contactor to disconnect a three-phase circuit. Copeland Corporation is not recommended to disconnect the second phase circuit.

In the United States, Copeland Corporation recognized contactors must meet the following four items:

· Contactors must meet ARI standard 780-78 "private contactor standard" requirements of the work and testing guidelines.

· Manufacturer must ensure the contactor at room temperature, at a minimum of 80 per cent of the nameplate voltages can be closed.

· When you use a single contact, the contact with rated current must be greater than motor nameplate current ratings (RLA), at the same time, the contactor must be able to withstand motor no-load current. If there are other contactor downstream load, such as motor fan, etc., must also be taken into account.

· When using two contactors, each contactor minutes winding stalling ratings must be equal to or greater than the compressor stall-winding ratings.

Contactor for rated current can not be lower than the compressor nameplate on the rated current. Specifications for small or low quality to withstand contactor, locked rotor compressor start and low voltage and current at the time of impact, prone to single-or multiple-phase-contact jitter, welding or even fall, causing damage to the motor.

Contact jitter of contactor frequently stop motor. Motor frequent start, great start current and fever, exacerbate winding insulation of aging. Every boot, magnetic torque of the motor winding on a tiny mobile and mutual friction. If there are other factors (such as metal shavings, insulation of lubricants, etc.), very easily lead to short circuit between the winding. Thermal protection system was not designed to prevent such damage. In addition, jitter of a contactor coil can easily fail. If you have contact with coil damage, prone to single-State.

If you contact device selection is small, contact cannot withstand the arc and due to the frequent open circulatory or unstable control circuit voltage may heat welding or contact shelf in shedding. Bonding of contact will result in a permanent state of single phase, so that the overload protector continuously loop connected and disconnected.

Special emphasis is required, contact contact spot after kg, rely on the contactor disconnect all power circuit of the compressor control (such as high-voltage control, pressure control, defrost control, etc.) will all fail, the compressor unprotected.

Therefore, when the motorburned down, check the contactor is essential to the process. Contactor is one of the leading motor damage are often forgotten.

Phase 4, power and voltage anomalies

Voltage is not working properly and phase can easily destroy any motor. Power supply voltage ranges cannot exceed the rated voltage ± 10%. Three-phase voltage unbalance must not exceed 5 per cent. High-power Motors must be independent of power supply to prevent the same line other high-power devices startup and operation resulting in lower voltage. Motor power cords must be capable of bearing motor rated current.

If there is a phase when the compressor is running, it will continue to run but will have a larger load current. Motor winding thermal soon will, under normal circumstances the compressor will be heat protection. When the motor windings cooling-temperature setting, contact will be closed, but the compressor does not start up, stalling, and enter "stalling-heat protection-stalling" dead loop.

Modern motor windings of difference is very small, power-phase equilibrium phase current differences can be ignored. Ideally, phase voltage always equal, as long as in either phase after another protector prevents overcurrent damage. Indeed difficult to ensure that the voltage balance.

Voltage unbalance percentage calculated, phase voltage and three-phase voltage means the maximum deviation of the values and the average three-phase voltage ratio, for example, nominal 380V three-phase power supply, the compressor terminals measure voltage 380V, 366V, 400V, you can calculate the average of the three-phase voltage, maximum deviation 382V to 20V, so the voltage unbalance percentage is five, 2 per cent.

As a result of voltage imbalance, in normal operation the load current imbalances are voltage unbalance percentage points for the number of 4-10 times. The preceding example, 5, 2% unbalanced voltage may cause 50 per cent of current imbalances.

United States National Electrical Manufacturers Association (NEMA) motors and generators standards publication that caused by an unbalanced voltage phase winding percentage of about voltage unbalance percentage points twice the number of squares. The preceding example voltage unbalance points 2 to 5, the winding temperature increase percentage for 54 per cent, the result is a phase winding overheating and the other two winding temperature properly.

A U, L, (underwriter's laboratories, United States) completed the survey, 43 per cent of the power companies allow 3% voltage unbalance, and another 30 per cent of the power companies allow 5% voltage unbalance.

5. insufficient cooling

Power larger compressors are usually back to the air cooling type. Evaporation temperature lower system quality stream, the less often. When evaporation temperature very low (in excess of the manufacturer's requirements), the flow is sufficient to cool the motor, motor can operate at higher temperatures. Air cooled compressors (generally not exceeding 10HP) dependence on gas, but on compressor ambient temperature and cooling air flow is explicitly required.

Refrigerant leakage would cause large numbers of systems quality flow decreases, motor cooling will also be affected. Some unattended freezer, etc., often have to wait until the cooling effect is very poor will find a large number of refrigerant leakage.

Motor overheat protection will occur frequently, some users do not have in-depth check reasons,To short-circuit the thermal protector, it is very bad things. It won't be long before, the motor will burn.

Compressor has safe operating range. Security conditions main consideration is the compressor and motor load and cooling. Since different temperature zones of compressor prices, past domestic refrigeration compressors use exceeding the scope of the industry is relatively common. With the expertise of growth and improvement of economic conditions, the situation has improved significantly.

6, compressor vacuum

Open refrigeration compressors have been forgotten, but there are some in the refrigeration industry site builders retained the past habits – compressor vacuum. This is very dangerous.

Air plays a role of insulation. Vacuum sealed containers, the electrodes between discharge easily occur. Therefore, with the compressor shell in vacuum deepens, shell Terminal in exposed or insulating layer between small broken winding insulation between lost power, the media, as soon as possible at the moment within the motor circuit burnout. If the shell leakage and may cause electric shock.

Therefore, no compressors vacuum, and the system is in the State of vacuum and compressor (not yet finished the vacuum and refrigerant), is strictly prohibited to compressor power.

Summary

Motor burned, conceals the winding corruption has caused the fault analysis difficult. However the compressor motor damage caused by underlying causes and not disappear. Poor lubrication or failure caused by abnormal load even stalling, thermal, shorten the service life; the windings windings in the scrap metal is to short circuit provides variable; contactors welding will cause the compressor protection cannot be executed; operation of the motor's power malfunctions will fundamentally destroy any motor, compressor vacuum, may cause the Terminal discharge.

Unfortunately, these negative factors will also throw each other: exception when load and no-load current can cause contact welding; a single contact la arc welding even can cause phase imbalance or single-phase; phase imbalance can cause heat; heat shortage causing wear; wear will produce scrap metal.

Therefore, properly installed using the compressor, as well as reasonable maintenance, you can prevent a negative factor is to avoid damage to the root of the compressor motor.

【 Weak current College 】 refrigeration system failure symptoms (1)

Refrigeration system fails, generally not possible to directly see fault area where, it is impossible to be a part of the refrigeration system a decomposition and Anatomy, only from the outside, check out the anomaly, a comprehensive analysis. In the check in is generally through see, hear, touch to understand the system operational status. When the system's operating pressure and temperature exceeds the normal range, in addition to the Interior and external ambient deterioration, or else will be a problem, it is important to determine the root causes of failure.
1. refrigeration system pressure and temperature detection
(1) the concept of refrigeration system pressure refrigeration system at run time can be divided into two parts with high and low pressure. High pressure over the exhaust from the compressor to the throttle valve, this paragraph referred to as evaporation pressure. Compressor suction pressure is called inspiratory pressure, suction pressure close to evaporation pressure difference between the two is the pipe flow resistance. Pressure loss in the following general restrictions in 0.018Mpa.
For convenience, the evaporation of the refrigeration system and the condensing pressure is the pressure in the compressor suction and exhaust port detection. Commonly known as the compressor suction and discharge pressure. Detection of refrigeration system suction and exhaust pressure aims to get the evaporating temperature refrigeration system and the condensing temperature, a means of obtaining the health of the refrigeration system.
(2) the temperature of the cooling system concept refrigeration system wide temperature range, evaporating temperature te, suction temperature ts, condensing temperature, exhaust gas temperature, etc. The refrigeration system operating conditions decisive is evaporating temperature te and condensing temperature tc.
1) evaporation temperature te refers to liquid refrigerant in the evaporator boiling temperature gasification. For example, the air conditioning unit of te. 5 ~ 7OC best as the air conditioning unit, i.e. evaporation temperature conditioning design te 5 ~ 7OC, when maintenance of air conditioning units when debugging, if te to between 5 ~ 7OC, expansion valve for high speed, detecting compressor suction pressure. Its purpose is to understand the unit run by evaporating temperature, while te cannot directly detect that only through detection of evaporation pressure corresponding to the evaporating temperature (by a lookup table of thermodynamic properties of refrigerant).
2) condensing temperature tc is superheated vapor refrigerant in the condenser condensation heat back into the liquid temperature. Condensing temperature cannot directly detect, only by testing its corresponding condensing pressure, then through the lookup table and thermodynamic properties of refrigerant. Condensing temperature high, its relative rise in condensing, they correspond to each other. Condensing temperature ultra-high, unit load, motor overload, to run, its cooling capacity corresponding decline in the consumption of power increase, should be avoided.
3) exhaust temperature td is the compressor outlet temperature (the temperature of the exhaust nozzle), detection of exhaust temperature measuring device is a must, not to set up General minicomputer, the provisional measure available semiconductor thermometer error detection, but larger. Exhaust temperature from suction temperature and condensing temperature, air temperature, or cooling temperature, exhaust gas temperature also increased, so have to control the suction temperature and condensing temperature, exhaust gas temperature can be stable.
4) suction temperature ts is the compressor suction pipe gas temperature, there are suction temperature detection temperature measurement device, generally small unit not to set up a temperature measurement devices, general maintenance while debugging to touch estimation, the air conditioning unit of suction temperature generally require control ts = 15OC to left for good. Exceeding this value on the refrigeration effect has a certain influence.
2. inspiratory pressure changes the impact of the refrigeration system
Refrigeration system is running, the suction pressure and evaporation temperature and flow of the refrigerant there is a close relationship. For purposes of system expansion valve, suction pressure and expansion valve to open degree, refrigerant charge, compressor cooling efficiency, and the magnitude of the load. Capillary system, suction pressure and condensing pressure, cooling capacity, the compressor refrigeration efficiency, as well as the magnitude of the load. To do this in check cooling system, you should press the suction tube with manometer. Detection analysis of inspiratory pressure on failure.
(1) the factors of inspiratory pressure low inspiratory pressure lower than normal, which factors are insufficient cooling capacity, cooling load, expansion valve opening small, condensation pressure low (of a capillary system), and the filter is not clear.
(2) the factors of inspiratory pressure high inspiratory pressure higher than the normal value, the element has too many refrigerant, refrigeration load, expansion valve to open degree, condensing pressure (capillary system) as well as compressor efficiency differential, etc.

【 Weak current College 】 vacuum pump features category---Power By 【 China power house network 】

Those taken out from the device, the device of internal gas reach vacuum machinery known as vacuum suction machine or vacuum pumps.
Structurally the vacuum pump can be divided into: reciprocating vacuum pump, rotary vacuum pumps and water jet vacuum pump, etc.

1, reciprocating vacuum pumps. Reciprocating vacuum pumps for pumping and not containing solid particle, non-corrosive gas. This vacuum pump's suction rate is large, the higher vacuum. It is widely used in the chemical plant. But its structure is complex, the amount of maintenance.

2, water ring vacuum pump. Water ring vacuum pump is a rotary vacuum pump.

3. Jet vacuum pump. Jet pump is the use of a pressure higher working fluid for the transmission of another fluid.

Circulating water pump is widely used in distillation, evaporation, crystallization, filter, vacuum, sublimation, low-temperature cooling circulating water pump is a vacuum pump and the combination of low-temperature cooling pump. That is, you can vacuum and can provide low-temperature cooling circulating water, vacuum distillation and vacuum concentration of good auxiliary equipment, the special adaptation is equipped with a rotary evaporator, which not only reduces the use of space, and reduces the vacuum, saving water, is widespread in modern laboratory equipment.