instruction manual - BHEL Bhopal

3 COMMISSIONING
SECTION 3
3.1 TESTING AFTER ASSEMBLY OF THE TRANSFORMER/ REACTOR
AT SITE.
After the transformer/reactor has been assembled at site, it shall be
tested in order to check that it has not been damaged during transport and
assembly to such an extent that its future operation will be at risk. Regarding
the performance of the test, refer to the testing method as per standards. The
results of the test shall be documented as detailed in Clause 3.2 "commissioning
checks -Transformers" and Clause 3.3 commissioning checks - Reactors.
3.1.1 APPLICATION OF VOLTAGE
If possible, the voltage should be increased step by step up to rated
voltage. This may be done by connecting the transformer/reactor to a generator
whose voltage is raised slowly. The higher the rated voltage of transformer/
reactor the more important it becomes that the application of the voltage is
done as described. If it is not possible to use a generator, the transformer/
reactor may be connected directly to a live line.
After the first application of voltage, the transformer/reactor shall be
checked carefully (gas relay, temperatures, leakages).
When the transformer/reactor has been is service for some weeks with
normal working temperature, all sealing joints shall be re-tightened.
3.1.2 ENERGISING
The initial magnetising current at the time of switching will be very
high. This depends on the particular moment in the cycle. The transformer
should always be soaked for few hours under constant care i.e. keep it
energized. If the breaker trips on differential, Buchholz or any other device,
the cause must be investigated before re-energising the transformer or reactor.
After successful charging, performance of the transformer/reactor , OTI, WTI
readings should be monitored for 24 hours and ensured that they are as per
loading.
3.1.3 ANALYSIS OF GAS
The gas conected in the relay will help to identify the nature of the fault.
It is suggested that the following checks are made at convenient intervals or
following the indication of accumulation of gas through alarm signal.
1. Rate of gas collection- The greater the rate of gas collection, the more
severe is the nature of the developing fault.
2. Colour of the gas helps in finding the affected material as follows.
Prepared By Samvet Lahari, Bhopal. Phone- 5277412