PROCESS OF PROTECTING A THYRISTOR KEY ELEMENT OF A PULSE GENERATOR ELECTRIC PULSE GENERATOR SYSTEM AND ELECTROSTATIC PRECIPITATOR

摘要

Method of protecting a thyristor switch element, of a pulse generator supplying a capacitive load, against damage during sparkovers which occur in the load, the method comprising triggering the thyristor or thyristors (T) in the switch element to conduction if a sparkover occurs in the load (CF) during a period of pulse decay. This can be achieved by starting a timer whenever a pulse starts, the timer running for the duration of the pulse, and detecting the slope of the voltage across the load as a function of time and triggering the thyristor to conduction when the slope of the voltage function exceeds a preset value at a time when the timer is running. Alternatively, for use in an energy conserving pulse generator system, where the pulse current consists of half a period with a current running in one direction and half a period with the current running in the opposite direction, the pulse current can be sensed and the thyristor triggered to conduction if a shift of current direction occurs during a period of pulse decay.