Page 330 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

Table 2
Sl.No. Current range Multiplier of fault current Time in seconds

1 Tap setting - 0.25A Tripping flag indicator Display tripping condition

TASK 2 : Identify internal parts of a single pole over current relay

Note: Instructor has to explain how to locate the internal parts and function of the circuit breaker
and ask the trainees to tabulate the identified part of the available circuit breaker in your section.
1 Remove the front cover by loosening the four knobs provided in the corner of relay and preserve the cover with
knobs carefully. (Fig 1)

Note: Don’t touch (or) try to operate any projected parts inside the relay.
2 Locate the aluminium disc fitted in the bottom of the spindle. (Fig 2)
3 Locate the Time Multiplier Setting (TMS) fitted in the top of the spindle.
4 Check the divisions marked on the TMS disc used for time setting.

5 Locate the spiral spring mounted on the top of spindle to bring back the disc top its original position after
tripping.
6 Locate the moving contact fitted along with the spindle on the top of disc enabling tripping circuit.

7 Locate the two terminals contact points acting as a switch to trip the circuit.

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CITS : Power - Electrician & Wireman - Exercise 112