Which thyristor behaves like two SCRs connected in parallel configuration & upside down?

Which thyristor behaves like two SCRs connected in parallel configuration & upside down corresponding to each other?

Option:

a. Diac
b. Triac
c. LASCR
d. Shockley Diode

Correct Answer: b. Triac

Explanation:

Triac is a bi-directional device comprising 5 layers and two SCRs connected in parallel combination upside down with respect to each other.

This implies that the anode of one SCR is connected to the cathode of the other and the associated gates are directly connected together.

Hence, it is possible to trigger the triac into conduction by both positive and negative voltages at its anodes as well as with both positive and negative triggering pulses at its gate.

Control of ac power supplied to load by switching ON & OFF modes during positive and negative half cycles is the major application of triac but is limited to the use of ac supply frequencies upto 400 Hz since it consumes more duration to recover to OFF state.