Influence of Capacitor Properties on the Irregular Ignition of Discharge Circuit Using Thyristor

Abstract

A misfire phenomenon taking place in a discharge circuit composed of a capacitor and a thyristor has been investigated. This circuit was operated at a frequency up to 198Hz. A misfire was observed in a circuit with a PET capacitor at low temperatures, while no misfire was observed with a PP capacitor at any conditions. Transient currents in the range of 40A-1mA were measured with a digital oscilloscope. In case of a PET capacitor, the current decreases exponentially at a given time constant initially, however it shows a slow decay which causes the misfire. This current is associated with residual charges trapped in the bulk of PET film.