Inverters are composed of many electronic components, such as semiconductor elements. During use and maintenance, the replacement of certain components is often necessary. Due to the composition or physical characteristics of the inverter, it will deteriorate over a certain period, thus reducing its performance and potentially causing malfunctions. Therefore, to prevent this, periodic replacement is necessary.
1. Replace the cooling fan
The cooling fan in the main circuit of the frequency converter accelerates heat dissipation for the semiconductor devices, ensuring normal operation below permissible temperatures. However, the lifespan of the cooling fan is limited by the bearings, approximately 10,000 to 35,000 hours. When the frequency converter operates continuously, the fan or bearings need to be replaced every few years. The replacement interval of the cooling fan is greatly affected by the ambient temperature; if abnormal sounds or vibrations are detected during inspection, the cooling fan must be replaced immediately.
2. Replace the capacitor
Large-capacity electrolytic capacitors are used in the intermediate DC circuit, and their performance deteriorates due to factors such as pulse current. Deterioration is greatly affected by ambient temperature and usage conditions. Under normal circumstances, the service life is about 5 years. The degradation of capacitors develops rapidly after a certain period of time, so the longest inspection cycle is one year, and the last six months or less is when they are close to the end of their lifespan.
3. Replace the timer
After several years of use, the timing of a timer can change significantly, so it should be replaced after checking the timing.
4. Replace the fuse
The rated current of a fuse is greater than the load current. Under normal operating conditions, its lifespan is about 10 years, during which time it needs to be inspected, maintained, or even replaced.
5. Replace the relay/contaminant
After a certain number of cumulative switching cycles, relays and contactors may experience poor contact, requiring inspection and replacement.
Secondly, now that we know which components may need to be replaced, here's a brief summary of the basic requirements for replacing them.
1) Understand the basic parameters and physical characteristics of the components that need to be replaced. Basic parameters include rated operating current, capacitor capacitance, resistor value, GTR Darlington parameters (current amplification factor), and IGBT (including IPM) switching characteristics and saturation voltage. Physical requirements include external dimensions, terminal positions, and mounting configuration. Then, replace the components with the required ones according to these requirements.
2) All connectors should be recorded or marked when they are disassembled to avoid misalignment during replacement or restoration.
3) Apply thermal grease evenly to the contact surface between the power device and the heat sink, and tighten it with screws.
Finally, in most cases, the machine is in operation. When the machine is not in operation, the frequency converter needs to be properly stored.
1) Keep
The indoor environment should be dry, free from direct sunlight, corrosive gases, and dust; the relative humidity should be between 20% and 90% and free from frost; the temperature should be between -10 and 30℃ (if the temperature is around 40℃, the storage period should not exceed 6 months; if the temperature is around 50℃, the storage period should not exceed 3 months).
2) Maintenance
Because the main circuit and control circuit of the frequency converter use a lot of electrolytic capacitors, if they are not used for a long time, the leakage current will increase and the withstand voltage will decrease, which will accelerate the deterioration (the higher the temperature, the faster the deterioration). Therefore, an external power supply should be applied at least once a year to restore the power supply time of 30 to 60 minutes. The key feature is that only the frequency converter needs to be powered on (it is not necessary to connect the motor). Just connect the power supply to the input terminal of the frequency converter.
