Page 50 - Practical Power System and Protective Relays Commissioning

46 Practical Power System and Protective Relays Commissioning

FIGURE 4.12 Induction motor construction.

For starting the induction motor there are a different methods some of the
common used one are as follows methods:
1. Rotor resistance method.
2. Stator resistance method.
3. Auto-transformer method.
4. Star delta method.

4.10 THE PRE-START COMMISSIONING TESTS OF
INDUCTION MOTORS

The following prestart commissioning tests should be undertaken:
1. Insulation resistance measurement. This test is done by using a Megger
test of phase-to-earth and phase-to-phase to check the dryness and qual-
ity of insulation.
2. Measurement of winding DC resistance, to check the winding and
circuits.
3. High voltage tests and insulation tests. This test is done to check the
quality of insulation.
4. Phase sequence check
5. Tests of protective relays. This test is done to check the protective
relays at the approved setting from the client’s engineers.
6. Tests of motor auxiliaries and motor cooling system.