Page 362 - Offshore Electrical Engineering Manual

CHAPTER
2
Generators

INTRODUCTION
At the time of testing, it is assumed that the manufacturer has already successfully
conducted the following tests (please refer to PART 2, Chapter 1):

1. open circuit test
2. iron loss test
3. short-circuit test
4. transient performance tests (sudden loading and three-phase short circuit)
5. voltage balance
6. heat run at full power
7. waveform analysis
8. vibration analysis
9. noise test
10. friction and windage losses
11. automatic voltage regulator (AVR) and control panel testing and calibration.

It may be necessary to repeat some of these tests in the module yard and/or offshore
if the machine is damaged or tampered with during transportation or installation.
Note that it is always essential to create a detailed written commissioning
procedure.
Having finally reached the offshore commissioning stage, it will be necessary to
make the generator safe for testing by carrying out the following:

1. Preparatory safety work
Assuming the generator has already been taken out of service, the generator
circuit breaker should be locked in the earth position and the associated AVR
voltage transformers (VTs) should be isolated and padlocked. If the circuit
breaker is not of the truck type, it must be padlocked off and a separate earth
safely applied. VT fuses should be removed, if the VT is not withdrawable.
2. Work safety coordination
It must be remembered that a large offshore generator will develop an appre-
ciable voltage from its residual field if it is allowed to rotate. This is less
unlikely than it sounds, especially if, at the same time, another commission-
ing team is anxiously attempting to complete the commissioning of the prime
mover. Although barring gear is normally provided on the larger machines and
may be used to prevent rotation, it may be necessary to provide some other

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