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Focus! The six major components of the inverter must be replaced regularly

Nov 30, 2020

Focus! The six major components of the inverter must be replaced regularly

1. Cooling fan


The power module of the inverter is a device with serious heat, and the heat generated by its continuous operation must be discharged in time. However, the life of the cooling fan is limited by the bearings. After about 10,000 to 35,000 hours (that is, 2 to 3 years according to the continuous operation of the inverter), the bearings, balls, and motors of the fan will wear out seriously, and the fan must be replaced once. It should be noted that the replacement period of the cooling fan is greatly affected by the surrounding temperature. If abnormal sound or vibration is found during the inspection, the cooling fan must be replaced.


2. Electrolytic capacitor


Large-capacity electrolytic capacitors are used in the intermediate DC circuit. Due to the influence of pulse current and other factors, their performance will deteriorate, and the degree of deterioration is greatly affected by the surrounding temperature and use conditions. Under normal circumstances, the service life is about 5 years. The deterioration of the capacitor develops rapidly after a period of time, so the longest inspection period is one year, and it is best to be within half a year when the end of life is approaching.


3. Timer


After the timer has been used for several years, the operating time will change greatly, so it is best to replace it after checking the operating time.


4. Fuse


In the DC bus circuit of major brands of inverters, fuses are often used for short-circuit protection. As the use time lengthens, under the impact of high current and temperature factors, the performance of the melt material will often degrade, causing the inverter to malfunction. For this reason, the fuse needs to be replaced every 7 years.


5. Contactor/relay


After the relay and contactor reach a certain cumulative switching times, poor contact occurs later, which requires inspection and replacement.


6. PCB circuit board


In fact, the PCB circuit boards used in the inverter, especially the switching power supply, voltage detection and other circuit parts, always need to withstand high voltage, so the electrical insulation performance of this part of the circuit PCB board will be inversely proportional to the use of time. This is for the use of multilayer PCB circuit boards. Compared with some inverters with poor workmanship, it is very disadvantageous. For this part of the circuit, 7 years should be used as a replacement cycle.

After understanding the components that may need to be replaced, we also need to pay attention to the basic requirements for replacing components:


1. Determine the basic parameters and appearance of the device to be replaced. Basic parameters include external size, capacitance of capacitor, resistance value of resistor, value of GTR Darlington (current amplification factor), switching characteristics and saturation voltage of IGBT (including IPM) devices, etc. The appearance requirements include external dimensions, terminal location and installation form, etc., and then replace the required components according to the same requirements.


2. Records or marks should be made when disassembling all connectors to avoid dislocation during replacement or restoration.


3. The contact surface of the power device and the radiator should be evenly coated with thermal grease and fastened with screws.


The inverter is affected by the external environment or its own structure, and will deteriorate after a period of use, thereby reducing the characteristics of the device and even causing malfunctions. Even if there are no obvious problems when using the above six major components, after a long time of use, it is still necessary to judge whether they can be replaced according to the use time to prevent the aging of the parts and cause problems in use.