Necessary Knowledge When Frequency Converter Failure(I)

The large capacity aluminum electrolytic capacitor of DC filter circuit of general frequency converter is usually composed of several capacitors in series and parallel to obtain the required voltage and capacity. In addition, because the capacity of electrolytic capacitors has greater dispersion, this will make the voltage them with is unequal. Therefore, the capacitor should have a shunt equal phase voltage resistance in parallel to eliminate the influence of dispersion, so the life of capacitor will seriously restrict the life of inverter.

If you have a problem with your inverter, check it with the following methods:

Static test: find the P end and N end of the inverter internal DC power supply, adjust the multimeter to the resistance X10 file, the red meter rod is connected to the P, the black watch rod is in accordance with R, S, T respectively, there are tens of ohm of resistance value normally, and basically balances. On the hand, the black watch rod is connected to the P end, and the red table rod is connected to R, S and T in turn, with a resistance value close to infinity. Connect the red table rod to the N end, The same result should be obtained by repeating the above steps. If there are the following results, it can be determined that the circuit has been abnormal. A. Resistive three-phase imbalances, indicating a fault rectifier bridge. B. when the red watch rod is connected to the P terminal, the resistance is infinite, which can determine the fault of the rectifier bridge or the fault of the starting resistance. .

Test inverter circuit: red watch rod connected to P end, black watch rod connected to U, V, W respectively, there should be tens of ohm of resistances, and each phase resistance value is basically the same, the inverse phase should be infinite. The same result should be obtained by repeating the above steps at the N end of the black table bar, otherwise it can be determined that there is a fault in the inverter module.