I already posted a couple of articles about the power transformer. In this post, I will discuss 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 substations, there is some special specification that you can get from the transformer supplier or the government. But when it’s about the indoor installation then you just need to follow some measurement and those are,
If the wall is one side only then the transformer body must maintain 0.5m distance from the wall.
If the wall is two sides then the transformer body must maintain 0.75m distance from each wall.
If the wall is three sides the transformer body must maintain 1.0m distance from each wall.
If the wall is four sides the transformer body must maintain 1.25m distance from each wall.
Related: Protection for a Power Transformer
Transformer Inspection:
Now you installed your transformer and it’s active right now. So you have to inspect your 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 the presence of moisture in oil.
2. Check insulator, bushes, and others. 3. Check the 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. |
Lightning
Change or filter transformer oil as necessary. |
| Five Year | The overall inspection which includes the lifting of the transformer core and coil. | Wash by housing down with clean dry oil. |
Transformer Commissioning:
- General Observation:
Completed Transformer
Junction Box
Control and relay panel and others.
- The Secondary Injection Test:
For the all protection relay.
- The Primary Injection Test:
Test on overcurrent relays on the low voltage side.
Test on suitability and operation of the earth fault relays on the low voltage side.
Test overcurrent 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 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.
Related: Transformer Schedule and Overhaul Maintenance
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