Danfoss training-common faults and analysis of compressors In this issue, we will talk about the common faults and analysis of compressors.
Common faults of compressor: (1) Motor burned out The operation of the motor is inseparable from the normal power input, reasonable motor load, good heat dissipation and protection of the winding enameled wire insulation. Starting from these aspects, it is not difficult to find that the reasons for the burning of the winding are as follows: o Abnormal load and locked rotor; o o Winding short circuit caused by metal chips; o o Contactor problem; o o Power phase loss and abnormal voltage; o o Insufficient cooling; o o Use a compressor to evacuate. o In fact, motor damage caused by multiple factors is more common. The above-mentioned unfavorable factors can also be caused by each other: abnormal loads and large currents during stalling may cause contactor welding; single contact arc drawing or even welding will cause phase imbalance or single phase; phase imbalance will cause heat dissipation; heat dissipation Insufficient will cause wear; wear will produce metal chips. Therefore, the correct installation and use of the compressor, as well as reasonable daily maintenance, can prevent the emergence of adverse factors, which is the fundamental method to avoid damage to the compressor motor.
o(2) Liquid strike oThe liquids that can cause compressor liquid blows are nothing more than the following sources: oo oLiquid return, that is, liquid refrigerant or lubricating oil flowing back from the evaporator to the compressor; oo oo oFoam when starting with liquid; oo oo oThere is too much lubricant in the compressor.
o(3) Lack of oil and insufficient lubrication oOil shortage is one of the compressor faults that can be easily identified. When the compressor is short of oil, there is little or no lubricant in the crankcase. oInsufficient lubrication: The direct cause of wear is insufficient lubrication. The lack of oil will definitely cause insufficient lubrication, but the lack of lubrication is not necessarily caused by the lack of oil. oThe following three reasons can also cause insufficient lubrication: oo oLubricating oil cannot reach the bearing surface; oo oo oAlthough the lubricating oil has reached the bearing surface, the viscosity is too small to form an oil film of sufficient thickness; oo oo oAlthough the lubricating oil has reached the bearing surface, it is decomposed due to overheating and cannot play a lubricating role.
Lack of oil leads to shaft hold The lack of oil will cause a serious lack of lubrication. The fundamental reason for the lack of oil is not how much and how fast the compressor runs, but the poor oil return of the system. Installing an oil separator can quickly return oil and extend the compressor's operating time without oil return. The design of the evaporator and the return air line must take oil return into consideration. Maintenance measures such as avoiding frequent start-up, defrosting regularly, replenishing refrigerant in time, and replacing worn piston components in time also help to return oil. o Return liquid and refrigerant migration will dilute the lubricating oil, which is not conducive to the formation of oil film; o o The failure of the oil pump and the blockage of the oil circuit will affect the oil supply and oil pressure, resulting in a lack of oil on the friction surface; o o The high temperature of the friction surface will cause the lubricant to decompose and make the lubricant lose its lubricating ability.
