Thyristor & Power Control Circuits Unit 2 – Silicon Controlled Rectifier
Exercise 3 – SCR GateTrigger and Holding Current
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to measure the gate trigger voltage and
holding current of a typical SCR by using dc measurement methods. You will verify your results
with a multimeter and an oscilloscope.
EXERCISE DISCUSSION
- The gate trigger voltage (VGT) is the minimum gate voltage (VGK) required to turn on the
SCR. - To determine the value of the gate trigger voltage, monitor the SCR while increasing the gate
voltage until the SCR turns on. - The SCR holding current (IH) is the minimum forward anode current (IA) required to keep the
SCR turned on. - To determine the holding current, monitor the forward anode current while decreasing the
current until just before the SCR turns off.