SOLID STATE CIRCUIT TECHNIQUES: DC SWITCHING DEVICES,

Solid-state dc switching devices were studied as part of an investigation of solid state circuit techniques. In the study, two devices were used as a switch a silicon controlled rectifier SCR and a trinistor controlled rectifier with gate turn-off. The first part of this report covers the investigation of circuits and methods to accomplish turn-off of the SCR. The SCR can be turned on by a signal on the gate however, additional circuitry is necessary to turn it off. The best results were obtained by using a circuit that connects a charged capacitor across the SCR, backbiasing it until it recovers its ability to block foward voltage. The last part of this report deals with the investigation of the trinistor controlled rectifier with gate turnoff used as a static switch. Tests were conducted to determine the device voltage drop, minimum gate voltage and current to fire, minimum gate voltage and current to turn off, and effect of overloading the device. Author