Class 2 (2nd Engineer) MET 📅 Jul 2022

Exam Question

With reference to preferential tripping in a marine electrical distribution system:

(a) With the aid of a sketch, describe a typical arrangement to provide three stages of tripping an instantaneous protection against short circuit.

(b) State why this protection is required.

Reference Answer

(a) Preferential trips operate after a fixed time delay, causing non-essential loads to be shed.
When the generator load reaches 110%, preferential Trip comes into operation as follows
First Stage Preferential Tripping (PT1):
Initiated when the current on a running generator exceeds 100% of the generator rating for a period of 10 seconds.

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