Class 2 (2nd Engineer) MET 📅 Jul 2018

Exam Question

(a) Sketch a circuit diagram of a push button direct on line contactor starter for a three phase incorporating overload and short circuit protection.

(b) Indicate on a sketch of the typical characteristic curves of current and torque against Speed, disadvantages of a direct on line start squirrel cage induction motor.

Reference Answer

(a) In the D.O.L starter circuit:
The main supply is connected to the contactor, which, when energized, connects the A.C motor to the supply.
The START push button activates the contactor, allowing the motor to start running.
Overload protection (O/L Relay) and Single Phase Protection Relay are connected in series with the contactor in the control circuit.

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