Find the specs plate thats typically attached to it. Or find out where it was used and what voltage they were getting from it. Or contact the manufacturer.
If possible count the primary and secondary coil turns and factor out the ratio.
All transformer has a specification name plate, stated the primary input voltage, secondary output voltage, KVA, frequency and e.t.c. That, is the only identification tag available to identify the specification of the transformer.
It is not possible to use the transformer capacity KVA to determine the secondary voltage. Maybe you need to ask around and see if any people using this type of transformer with the same capacity and the same primary voltage. But then again, even they do have it as the same transformer as your unit, your chances of accuracy of guessing the secondary voltage still remain at 50-50 % correct.
The best way is to ask the manufacture to test it.
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Very easy, just use transformer turn ration test (TTR) equipment which will give you the exact turns ratio of transformer windings "Secondary & Primary" and then simply calculate the secondary voltage.
Do you know if this is a step down transformer? If so you may put a 400v three phase supply on the primary winding and measure the output voltage on the secondary. From the input and output voltages you will be able to calculate the ratio.
1. Look into the transformer bushing and clearly identify the HT and LT side. The HT bushing is larger than the LT bushing.
2. Apply 3 phase low voltage (say 440V L-L) to HT side. Keep the LT side Open
3. Precisely measure the LT side Line to Line voltage (say 4 V)
4. As you said your primary is 44000 V, then your secondary voltage will be (44000 x 4) / 440 = 400 V
Precaution:
It is very important to identify the HT and LT side first and then proceed, otherwise DON'T PROCEED to STEP 2.
Make sure you apply voltage in HT side, NOT in LT side.
-MS
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"All my technical advices in this forum must be consulted with and approved by a local registered professional engineer before implementation" - Mohammed Samad (Linkedin Profile: http://www.linkedin.com/in/msamad)
Just to add a little.The HV bushing is taller in height with smaller conductor.The LV bushing is much shorter but bigger in diameter,with very thick copper terminal.For DYn transformer,3 bushing on primary and 4 bushings on secondary side. ( don't buy transformer from scrap yards )
Transformers and Secondary Voltage
Re: secondary voltage of transformer
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