Class 2 (2nd Engineer) MET 📅 Dec 2024

Exam Question

(a) What is a silicon controlled rectifier (SCR)? How is the breakover voltage of the SCR defined? (6)

(b) A d.c. motor takes an armature current of 110 A at 480 V. The resistance of the armature circuit is 0.2 Ω. The machine has six poles and the armature is lap-connected with 864 conductors. The flux per pole is 0.05 Wb. Calculate: (10)

(i) The speed;

(ii) The gross torque developed by the armature.

Reference Answer

A SCR is a 4-layered PNPN switching solid-state current controlling device. These are unidirectional devices. SCR is triggered by a current going into the gate.
It has three modes of operation:
Forward blocking mode (OFF state)
Forward conducting mode (ON state)

Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.

View plans Browse library

← Browse more questions

Prepare on Android — MeoMock on Google Play