Editing Thyristor (section)

== Failure modes ==

Thyristor manufacturers generally specify a region of safe firing defining acceptable levels of voltage and current for a given [[operating temperature]]. The boundary of this region is partly determined by the requirement that the maximum permissible gate power (P<sub>G</sub>), specified for a given trigger pulse duration, is not exceeded.<ref>[https://archive.today/20130415150725/http://www.powerguru.org/2012/05/09/safe-firing-of-thyristors/ ''"Safe Firing of Thyristors"''] on powerguru.org</ref>

As well as the usual failure modes due to exceeding voltage, current or power ratings, thyristors have their own particular modes of failure, including:
* Turn on di/dt: in which the rate of rise of on-state current after triggering is higher than can be supported by the spreading speed of the active conduction area (SCRs & triacs).
* Forced commutation: in which the transient peak reverse recovery current causes such a high voltage drop in the sub-cathode region that it exceeds the reverse breakdown voltage of the gate cathode diode junction (SCRs only).
* Switch on dv/dt: the thyristor can be spuriously fired without trigger from the gate if the anode-to-cathode voltage rise-rate is too great.