1. Precautions

The operator must be familiar with the basic working principle and functional characteristics of the inverter and have basic knowledge of electrical operation. Before inspecting and maintaining the inverter, the main power supply of the equipment must be completely cut off and the inverter indicator must be completely off.

2. Daily inspection items

Before the inverter is powered on, the temperature and humidity of the surrounding environment should be checked. If the temperature is too high, the inverter will overheat and alarm. In severe cases, it will directly damage the inverter power device and short circuit the circuit. If the air is too humid, it will cause a direct short circuit inside the inverter. When the inverter is running, pay attention to whether its cooling system is normal, such as whether the air duct exhaust is smooth and whether the fan has abnormal sound. Generally, inverters with higher protection levels, such as inverters above IP20, can be directly installed in the open, and inverters below IP20 should generally be installed in a cabinet. Therefore, the heat dissipation effect of the inverter cabinet will directly affect the normal operation of the inverter. The exhaust system of the inverter, such as whether the fan rotates smoothly, and whether there is dust and blockage at the air inlet, are all areas that cannot be ignored in our daily inspections. Whether the motor reactor, transformer, etc. are overheated and have odors; whether the inverter and motor have abnormal sounds; whether the current display on the inverter panel is too large or the current change is too large, and whether the output UVW three-phase voltage and current are balanced.

3. Regular maintenance

Clean the cooling duct and internal dust of the air filter. Check whether the screws, bolts and plug-ins are loose, and whether the input and output reactors have short circuits to the ground and phase-to-phase resistances, which should be greater than tens of megohms. Check whether the conductors and insulators are corroded. If so, wipe them clean with alcohol in time. If conditions permit, use an oscilloscope to measure the stability of the output voltages of the switching power supply, such as 5V, 12V, 15V, 24V and other voltages. Measure whether the square waves of the waveforms of each channel of the drive circuit are distorted. Whether the UVW phase-to-phase waveform is a sine wave. Whether there are traces of sparking on the contacts of the contactor, if serious, replace them with new ones of the same model or larger than the original capacity; confirm the correctness of the control voltage and conduct a sequential protection action test; confirm that there is no abnormality in the protection display circuit; confirm the balance of the output voltage of the inverter when it is running alone.

It is recommended to check regularly, which should be done once a year.

4. Replacement of spare parts

The inverter is composed of many components, some of which will gradually degrade and age after long-term operation, which is also the main reason for the inverter failure. In order to ensure the long-term normal operation of the equipment, the following components should be replaced regularly:

1. Cooling fan

The power module of the inverter is the device with the most serious heat generation. The heat generated by its continuous operation must be discharged in time. The life of the fan is generally about 10Kh-40Kh. The fan should be replaced every 2-3 years according to the continuous operation of the inverter. The direct cooling fan is divided into two-wire and three-wire. One of the two-wire fans is positive and the other is negative. Do not connect them wrongly when replacing; the three-wire fan has a detection line in addition to the positive and negative poles. Be careful when replacing, otherwise it will cause the inverter to overheat and alarm. AC fans are generally divided into 220V and 380V. Do not make a mistake in the voltage level when replacing.

2. Filter capacitor

Intermediate circuit filter capacitor: also known as electrolytic capacitor, its main function is to smooth DC voltage and absorb low-frequency harmonics in DC. The heat generated by its continuous operation plus the heat generated by the inverter itself will accelerate the drying of its electrolyte, directly affecting its capacity. Under normal circumstances, the service life of the capacitor is 5 years. It is recommended to check the capacitor capacity regularly once a year. Generally, it should be replaced if the capacity decreases by more than 20%.