Common problems encountered in the use of the transformer ratio tester

Common problems encountered in the use of the transformer ratio tester:

Summary of frequently encountered problems during use:

1. Connect the high and low voltage test wires in reverse during the test, which will damage the instrument in common ratio testers. A protective device is added to some new testers, which will blow the fuse of the test circuit when the test leads are reversely connected.

2. The test value does not match the calculated value, and the wiring group does not match the nameplate wiring group. It may be that the instrument is damaged or there is a problem with the transformer.

3. Precautions for testing The wire clamp must be clamped reliably to prevent the wire clamp from falling off during the test. In previous tests, it was found that the wire clamp fell during the test, which in turn caused damage to the instrument.

4. It is forbidden to touch the copper medal of the tested transformer wiring during the test.

The purpose and significance of the ratio test

(1) Check whether the transformation ratio is consistent with the nameplate to ensure the correct transformation of the voltage

(2) Check whether the position of the tap changer is correct

(3) After the transformer fails, check whether there is an inter-turn short circuit or open circuit between the winding turns by measuring the transformation ratio (handover and overhaul)

(4) Measure the unbalance degree of the transformation ratio of the three-phase transformer itself, and determine the size of the zero-sequence component

(5) Accurately obtain the transformation ratio and judge whether the transformers can be operated in parallel

When the no-load voltage difference on the secondary side of the two transformers running in parallel is 1% of the rated voltage, the circulating current in the windings of the two transformers will reach about 10% of the rated current, which will increase the loss of the transformer and occupy the capacity of the transformer. Therefore, the difference of the transformation ratio should be limited within a certain range

At present, the common transformation ratio group tester (you need to input some data on the nameplate, generally input the rated voltage, rated tap ratio, number of gears), the general power supply needs to supply 220V mains. Intelligent transformation ratio test instrument (blind test can be tested without inputting any parameters), using a new single-chip microcomputer, powered by a lithium battery inside, supporting data storage and U disk dumping, and realizing microcomputer processing such as printing.

HZBB-10A Transformer Turns Ratio Tester