Input and Output Static Check Procedure for VFDs
iS7s from 11~22kW (200V and 400V) and 30~160kW (400V only) will read open on the DCP side for the S and T phases.
There are two types of power circuits to check, SCR and diodes. Diodes are typically found in smaller models while SCR can be found in our larger models like H100s and IS7s.
Before performing a diode test (sometimes called a static test) make sure to disconnect all power cables (R, S, T) and motor output cables (U, V, W). Next, check whether the electrolytic capacitor discharged before commencing your test.
When the circuit is open, the DMM will indicate a high resistance of several MΩ. In some cases the DMM may indicate a closed circuit (low resistance) and then indicate a high resistance due to the capacitors. When the circuit is closed, the DMM indicates a resistance of several hundred kΩ or less.
Displayed values may not be constant as they depend on the module and test type. However, the value measured between phases can be considered satisfactory if the value is measured within ±10%.
Disclaimer: M100 and G100 have no DC bus terminals. Different model numbers will have different capacities