I already posted couple of article about power transformer. In this post I will discuss about the indoor transformer installation, inspection and commissioning.
Transformer Indoor Installation:
There is some specification if you want to install a power transformer inside a room. But you can do it when you get the permeation from the government. In my country if we are making a substation and our supply voltage is 11 KV then we can install our transformer inside a room.
But when its 33KV or above then we have to go outdoors. For outdoor substation there is some special specification that you can get form the transformer supplier or the government. But when it’s about the indoor installation then you must need to follow some measurement and those are,
If wall is one side only then transformer body must maintain 0.5m distance from wall.
If wall is two sides then the transformer body must maintain 0.75m distance from each wall.
If wall is three sides the transformer body must maintain 1.0m distance from each wall.
If wall is four sides the transformer body must maintain 1.25m distance from each wall.
Related: Protection for a Power Transformer
Now you installed your transformer and it’s active right now. So you have to inspect you transformer within a certain period of time and those are,
|Inspection Frequency||Item to be inspected properly||Remarks|
|Every Six Month||1. Check the oil for dielectric strength and presence of moisture in oil.
2. Check insulator, bushes and others.
3. Check cable box.
|Replace or filter if necessary.|
|Each Year||1. Check all lighting arrestor.
2. Check earth resistance.
3. Check all relay, alarms, contacts etc.
4. Check transformer oil for sludge, acidity and flash point if necessary.
Change or filter transformer oil as necessary.
|Five Year||Overall inspection which include lifting of transformer core and coil.||Wash by housing down with clean dry oil.|
- General Observation:
Control and relay panel and others.
- The Secondary Injection Test:
For the all protection relay.
- The Primary Injection Test:
Test on over circuit relays on the low voltage side.
Test on suitability and operation of the earth fault relays on the low voltage side.
Test over current relays on the high voltage side.
Test on suitability and operation of the earth fault relays on the high voltage side.
- Ratio Testing:
With 415 V applied on high voltage side measure the voltage between all phases on low voltage side for the every tap position.
- Tripping Test:
High voltage side main breaker.
Low voltage side main breaker.
Inner tripping tests.
Winding temperature testing.
- Calibrate all Earthing Resistance.
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