Use a multimeter to check whether the reverse conduction thyristor is good or bad
1. check retrograde
Select the R×1 range of the multimeter, connect the black test lead to the K pole, and the red test lead to the A pole. The resistance value should be 5~10Ω. If the resistance is zero, it proves that the internal diode is short-circuited; if the resistance is infinite, it means that the diode is open.
2. Measure the forward DC breakover voltage V(BO)
After connecting the circuit, shake the megohmmeter at the rated speed to make the RCT break down in the forward direction, and read the V (BO) value from the DC voltmeter.
3. Check trigger capability
Example: Use a 500-type multimeter and a ZC25-3 megohmmeter to measure a S3900MF reverse-conducting thyristor. Select R×1k, R×100, R×10 and R×1 in order to measure the reverse resistance between A-K poles, and at the same time use the reading voltage method to obtain the reverse conduction voltage VTR of the internal diode (actually the forward voltage of the diode VF). Then use the megohmmeter and multimeter to measure the V (BO) value at 500VDC. All the data are organized into Table 1. This proves that the quality of the RCTs tested is good.
