化工英文文献翻译.docx

1、化工英文文献翻译Three Common Details of The Compressor Failure Analysis Compressor Fault Analysis (1) - motor burned Motor compressor (hereinafter referred to as the compressor) of the fault can be divided into motor failure and mechanical failure (including the crankshaft, connecting rod, piston, valve, cy

2、linder head pad, etc.). Mechanical failure is often the motor overload or stall, is one of the main motor damage. Damage mainly to the motor stator winding insulation damage (short circuit) and the circuit and so on. Stator windings was found damaged hard time, could eventually lead to winding burne

3、d. Winding burned, cover up some cause or direct cause of the phenomenon of burning, making the subsequent analysis and cause investigation more difficult. However, the operation of the motor power input is inseparable from the normal, reasonable motor load, good heat dissipation and winding wire in

4、sulation layer of protection. From several aspects, not difficult to find reason than burnt windings are six: (1) abnormal load and stall; (2) Winding short circuit caused by metal shavings; (3) contactor problems; (4) Power phase and voltage abnormalities; (5) inadequate cooling; (6) compressor vac

5、uum. In fact, many factors contributed to the more common motor damage. 1. Abnormal loads and stall Motor load requirements, including compressed gas load and the load required to overcome mechanical friction. Pressure ratio is too large, or the pressure is too large, the compression process will be

6、 more difficult; and increased friction caused by lubrication failure, and extreme cases of motor stall, will greatly increase the electrical load. Lubrication failure, friction increases, is the leading cause of abnormal load. Back to the diluted lubricating oil, oil heat, oil coking deterioration

7、and lack of oil and so will disrupt normal lubrication, leading to lubrication failure. Back to the diluted lubricating oil, affecting the normal friction surface film formation, or even washed away the original film, increasing friction and wear. Compressor overheating will cause the thinning or ev

8、en high-temperature coking oil, affecting the normal film formation. System back to the oil well, the compressor short of oil, they can not maintain normal lubrication. High-speed rotating crankshaft, connecting rod piston speed movement, there is no friction surface protection film will quickly hea

9、t up, local high-temperature rapid evaporation of the oil or coke, to make it more difficult to lubricate the parts, a few seconds can cause severe localized wear. Lubrication failure, local wear, the need for greater torque to the crankshaft. Low-power compressor (such as refrigerators, home air co

10、nditioning compressor) as the motor torque, lubrication failure often occurs after the stall (the motor can not rotate) phenomenon, and enter the stall - Thermal protection - Locked death cycle, motor burn only a matter of time. The high-power semi-closed compressor motor torque large, local wear wi

11、ll not cause stall, the motor power will be within a certain range increases with the load, causing more serious wear and tear, and even lead to bite cylinder (live seca in cylinder), rod fracture and other serious damage. When the current stall (stall current) is about 4-8 times the normal running

12、current. The moment of starting the motor, the current reached a peak close to or stall current. Because the resistance heat release proportional to the square with the current, start and stall when the winding current will heat up quickly. Thermal protection can protect the electrode in the stall,

13、but generally will not have a response soon, can not prevent such frequent starting winding due to temperature changes. Frequent starts and abnormal load, so that the test winding subjected to high temperature will reduce the magnet wire insulation. In addition, the compressed gas with the compressi

14、on ratio will be required to increase the load and pressure increases. Therefore, the high temperature compressor for low temperature, or low compressor for high temperature, will affect the electrical load and heat, is not appropriate, will shorten the electrode life. Winding insulation deteriorati

15、on, if there are other factors (such as metal shavings form conductive loops, acid oil, etc.) with, it is easy to cause a short circuit and damage. 2. Scrap metal caused by short circuit Winding metal particles are mixed and ground insulation value of the low short-circuit the culprit. The normal vi

16、bration of the compressor running, and every time you start winding by the magnetic force of the pipe, will promote inclusion in the winding and the winding metal shavings between the relative motion between the magnet wire and friction. Sharp edges will scratch the enameled metal shavings insulatio

17、n, causing short circuits. Sources including the construction of metal debris left behind by the brass shavings, welding slag, compressor internal parts wear and damage (such as broken valves), the fall of the metal shavings and so on. For the closed compressor (including the closed scroll compresso

18、r), the metal shavings or broken, would fall on the winding. For semi-hermetic compressors, and some particles with the gas and oil flow in the system, and finally assembled in the magnetic winding; and some metal shavings (such as bearing wear and stator and rotor wear (sweep bore) is generated) wi

19、ll be directly on the winding. Winding metal shavings gathered after a short circuit is only a matter of time. Need to draw particular attention to the two-stage compressor. In the two-stage compressor, back to the normal gas and oil directly back into the first grade (low grade) cylinder, compresse

20、d by the pressure of the cooling tube into the motor winding cavity, and the general single-stage compressor and then as second-class (high pressure stage cylinder.) Back to the gas with oil, the compression process has been skating on thin ice, if there are back to liquid again, the first stage cyl

21、inder valve can easily be broken. Broken by the pressure valve can enter the winding tube. Therefore, the two-stage compressor than the single-stage compressors are more likely to electrical short circuit caused by metal shavings. Unfortunately, things tend to conspire a piece of the compressor in t

22、he boot of a problem when the news channels is often the oil burning. Severe wear of metal surfaces when the temperature is very high, while oil above 175 C at the start of coking. System, if there is more moisture (vacuum pits not ideal, big oil and refrigerant water, negative pressure air into the

23、 return pipe burst, etc.), lubricants acid may occur. Acidic oil will corrode copper and winding insulation layer, on the one hand, it can cause copper plating phenomenon; on the other hand, this acid containing copper atoms very poor insulation properties of lubricating oil, provided the conditions

24、 for the winding circuit. 3. Contactor problem Contacts is an important component in the motor control circuit, one of the best selection of irrational destruction of the compressor can be. The right choice according to the load contacts are extremely important. Contactor must be able to meet the ha

25、rsh conditions, such as rapid cycling, continuous overload and low voltage. They must have enough surface area to distribute the heat generated by the load current, contact material should be selected to start or stall in such circumstances to prevent high current welding. For safe and reliable, whi

26、le the compressor contactor to disconnect the three-phase circuit. Copeland is not recommended way to disconnect the two-phase circuits. In the United States, Copeland approved contactor must meet the following four: contactor must meet ARI Standard 780-78, Standard for special access provisions of

27、the work and testing guidelines. The manufacturer must ensure that the contacts at room temperature in the lowest 80% of nameplate voltage can be closed. When using a single contactor, the contactor must be greater than the motor nameplate rated current rating (RLA). Meanwhile, the contactor must be

28、 able to withstand motor stall current. If there are other loads downstream of the contactor, such as electrical fans, and so must also be considered. When using two contactors, each contactor rating of the sub-winding stall must be equal to or greater than the rating of the compressor stall half-wi

29、nding. Contacts can not be less than the rated current of the compressor nameplate rated current. Size small or poor quality of contact can not withstand the compressor starts, stall, and low voltage high current impact, single-phase or multiphase prone to contact bounce, the phenomenon of welding o

30、r even fall off, causing electrical damage. Contact jitter frequently start and stop the motor contactor. Frequent motor starts, a huge starting current and heat, will aggravate the winding insulation aging. Each time you start, the magnetic torque to the motor windings have small mobile and mutual

31、friction. If there are other factors with (such as metal shavings, poor insulation oil, etc.) can easily lead to short circuits between windings. Thermal protection system is not designed to prevent such damage. In addition, the jitter of the contactor coil easy to failure. If you have contact with

32、the coil is damaged, prone to single-phase state. If the small selection of the contactor, the contact arc, and can not afford to open due to the frequent instability of circulatory arrest or heat generated by the voltage control loop may be welded together or from the contact frame in the loss. Wel

33、ding of the contacts will have a permanent single-phase state, the overload protection device continuously cycle on and off. Needs to be stressed is that after the welding contactor, disconnect the compressor contactor power dependence of all the control loop (such as high and low pressure control, hydraulic control, defrost c