SCR Triggering Circuits for AC Phase Control

Question 1

What are the two common forms of triggering used with SCR’s?

Answer 1

resistor triggering and resistor-capacitor triggering

Question 2

If resistor triggering is used, the SCR can be fired between _____ degrees up to _____ degrees in the positive half-cycle

Answer 2

0° to 90°

Question 3

If resistor-capacitor triggering is used, the SCR can be fired from ____ degrees up to ____ degrees in the positive half-cycle

Answer 3

0° to 180°

Question 4

Regardless of the type of triggering circuit, the SCR will always block for at least ____ degrees of the AC cycle

Answer 4

180°

Question 5

What determines the rate at which the capacitor charges to the required SCR positive gate voltage in the resistor-capacitor phase-control circuit?

Answer 5

the ohms setting of the rheostat in series with the capacitor (assumes a non-variable capacitor)