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Tuesday, November 1, 2011

Measurement of No-load Loss and Current for Power Transformer

Here are the procedure for testing of no-load loss and current for Power Transformer. This procedure has been simplified and given by the Hyosung manufacturer for observation purposes during factory acceptance test at their factory.

1. BSJ-05, transformer measuring system
2. Generator
3. Test transformer
BSJ-05 Transformer Measuring System including computer

Test Generator

Test Transformer

Testing schematic

Test procedure
Energize the transformer from the tertiary winding side with the 60Hz supply, and the high and low voltage terminals will be open. And at the same time the neutral will be earthed. At this point, we will measure the loss and the current of the transformer at 115/110/105/100/95/90% rated voltage.The mean voltage, r.m.s voltage, average current and no load losses will be recorded
Setting up the Power Transformer  in preparation for the measurement of No load loss and current test.

Setup of the equipment

Checking of test results on the computer

Checking point
The limits are set by the buyer of transformer as per contract agreed upon. An example would be, the no-load loss of 100% should be about 21kW (not more than 10%) and the no-load current of 100% should be about 0.2% (not more than 30%) based on 100% rated current. After the entire dielectric test we will have a no load test again. We will compare the two no-load data. If the manufacturer has not attain the specifications by the buyer, there would be a corresponding penalty for each additional kW in terms of dollars.
The excitation curve, which plot between exciting current and percent of exciting voltage, will be presented on the final test result.


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