• Categories:FAQ
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• Time of issue:2022-03-14
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(Summary description)(1) Causes of short circuit between turns
1) The quality of enameled wire is poor, especially for thin wires. Pinhole points are allowed in the wire standard, and short circuits are easy to occur when winding.
2) The enameled wire is damaged during winding, such as damage to the paint film, scratches, knots, etc.
3) The pad paper is crushed or the pad is displaced.
4) There are burrs in the lead wires or solder joints, which press the insulating layer.
5) When using copper shielding, the interlayer insulation is not well-padd, so that the shielding layers touch head and tail.
6) Improper selection of insulating varnish during dipping, its solvent will corrode the enameled wire or the insulating varnish has a large shrinkage stress, and the coil shrinks when drying, causing a short circuit.
(2) Detection of inter-turn short circuit
1) Transformers should be tested for induced voltage. In order to improve the detection sensitivity, the test frequency is preferably 400HZ.
2) Detected by pulse comparison method. A high-voltage square wave is applied to both ends of the transformer winding, and the attenuation oscillation waveform of the two coils is compared to judge whether the short circuit is not.
3) Measure the no-load loss of the transformer. When the core loss is qualified, and the no-load loss increases, it means that the coil has a short circuit.
4) The Q value of a high-frequency transformer or inductor can be measured to determine whether there is a short circuit.