Controlled Rectifiers

Question 1

What are the names of the three terminals of an SCR?

Answer 1

Anode
Cathode
Gate

Question 2

Define an SCR.

Answer 2

Silicon-controlled rectifier.

A member of the thyroid your family of electronic devices that acts as a uni-directional solid state switch.
When the SCR is in the off state, it acts like an open switch.

Question 3

What are three types of SCR configuration available?

Answer 3

Flat pac or tan style (low current)

Stud mount (medium power ccts)

Puk style (very large power ccts)

Question 4

What does heat sink protect an SCR from?

Answer 4

Heat sink limits the chances of break over voltage being reduce from becoming to hot.

Question 5

What are the two requirements for an SCR to turn on and conduct?

Answer 5

1. The anode must be more positive than the cathode (fed bias)
2. The gate must have positive current pulse.

Question 6

What is the value of the SCR holding current?

Answer 6

Approximately 1mA per A of the rates anode current.

Question 7

What are three undesirable ways to trigger an SCR?

Answer 7

Exceeding break over voltage

Fluctuations in voltage

Temperature changes

Question 8

While triggering an SCR with positive gate pulse, what must be done to limit the current?

Answer 8

Add a resistor in series with the gate to limit current and prevent gate burn out.