How to determine the malfunction of thyristors

Loss of thyristor performance may occur due toand:

a) open circuit inside the device (combustion);

b) loss of controllability (combustion of the control electrode circuit);

c) loss of locking ability in the forward or reverse direction (breakdown);

d) breakage of conclusions.

An inoperative thyristor can be detected using an AC voltmeter, an ohmmeter, or a test circuit.

An inoperative thyristor in a circuit under AC voltage can generally be detected with a voltmeter.

The variety of circuits and variable values ​​of the thyristor control angles do not allow specifying specific values ​​of the voltage on the thyristor for various reasons for inoperability.

Tentatively, during combustion, the voltage on the thyristor will be higher, and during breakdown less than that of a similar operable device.

The combustion of the thyristor or its control transition can be determined using a test circuit:

The most common values ​​of control currents are approximately an order of magnitude lower than the maximum values.

The resistor resistance is selected from the condition that the thyristor direct current is limited to 30-50 mA for low power devices and 400 to 500 mA for medium and high power.

The moment and currents of inclusion and control are controlled by ammeters.