Here are some tips for testing a transformers. Have a look on this presentation...

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Rajasthan Powergen
How can you test a
transformer exactly?

2. Rajasthan Powergen, the leading transformer
manufacturing company in India is providing tips
using which you can get the idea as how to test the
transformer.

3. Transformer: A device that is
used to transfer electrical
energy from one circuit to
another.

4. The transformer will either increase or decrease
voltage in Alternating current (AC).
There are two types of AC transformers
1. Linear transformer – Used in radios, project kits
etc.
2. Switch mode power transformer -Used in
monitors, TV’s and fax etc

5. Main work of a transformer is to change the AC voltage.
In power transformers, the core is made of iron. In radio
frequency transformers the core is made of ferrite of air.
A step down transformer has lower AC voltage output in
its secondary windings compared to the AC input
voltage in the primary windings.

6. A step up transformer has higher secondary windings
compared to the AC input voltage in the primary
windings.

7. Testing of Transformers:
When transforms fail to work, they need to be
tested. Generally trained people who know how
to repair it should test it. Failure of a
transformer is rare in electronic equipments.

8. If lot of current passes through windings and it heats up, then it can
either open up completely or the insulation between the turns of the
wires can be affected resulting in the coil being partially or
completely shorted.

9. Best method to test a transformer:
1. Remove the transformer from the board.
2. Then first check the primary windings.
3. To find out the primary winding, see the filter cap the
positive pin to see where it goes in the circuit which will
lead you to the pin of the transformer. Then check the
middle pin which is the Drain which will lead you to
another pin of the transformer. These two pins make the
primary windings.
4. By checking the resistance you will find out if it is open.
Ringer test is used to check whether it is shorted. If it is
shorted, it will blow up the power section.

10. Cheapest ringer test is fly back tester. When the probes are
connected to the primary windings, the result is seen on the Led bar
graph.
Bar shows 4-8: winding is in good condition.
Bar shows 1-2: there is partial short.
Led goes off completely: there is big short.
Expensive ringer tester will check and test transformers, high,
current, and pulse transformers, electric and custom transformers.

11. Another method of testing is to use a light bulb.
•Remove one of the primary windings pin.
•Connect it to a 60 watt bulb. One end will be connected
to the circuit and the other end will be connected to the
transformer pin.
•If light in the bulb shines, it means that winding is
shorted. If the light in bulb goes off it means that
winding is alright.

13. It is necessary to have expertise knowledge and
awareness about work before testing a
transformer. If you are unaware about it, you
should be aware about different methods of
testing and will be able to know its various
aspects. This is the reason why the tips are
provided by the leading distribution transformer
manufacturing company in India for your help.