Influence of capacitor properties on irregular ignition of discharge circuit using a thyristor.

A misfire phenomenon taking place in a discharge circuit composed of a capacitor and thyristor has been investigated. This circuit was operated at a frequency of up to 198 Hz. A misfire was observed in a circuit with a PET capacitor at low temperatures, while no misfire was observed with a PP capacitor under any conditions. Transient currents in the range of 40 A to 1 mA were measured with a digital oscilloscope. In the case of a PET capacitor, the current initially decreased exponentially at a given time constant, but exhibited a slow decay which caused the misfire. This current is associated with residual charges trapped in the bulk of the PET film. © 2001 Scripta Technica, Electr Eng Jpn, 137(2): 1–7, 2001 [ABSTRACT FROM AUTHOR]