Transformer how to do no load test
3, through the no-load test can be found in the transformer the following defects:
Poor insulation between silicon steel sheets. Between the core, between the pieces of local short circuit burn.
Wear the core bolts or tie the strip, the pressure plate, the yoke and other insulation part of the damage, the formation of short circuit.
Magnetic circuit in the silicon steel loose, dislocation, air gap is too large.
Core multi-point grounding.
The coil has turns, inter-layer short circuit or parallel branch turns ranging from ampere-turns and so on.
Misuse of high consumption of low quality silicon steel sheet or design calculation is wrong.
The test voltage of the no-load test is the rated voltage of the low-voltage side. The no-load test of the transformer mainly measures the no-load loss. No-load loss is mainly iron loss. The magnitude of the iron loss can be considered independent of the size of the load, ie the loss at no load is equal to the iron loss at the time of the load, but this is the case when the rated voltage is present. If the voltage deviates from the rated value, the no-load loss and no-load current will change abruptly because the magnetic induction in the transformer core is in the saturation section of the magnetization curve. Therefore, the no-load test should be carried out at rated voltage.
Note: In the measurement of large transformer no-load or load loss, because the power factor is very low, can achieve cosφ less than and equal to 0.1. So it is necessary to use low power factor watt table.
Transformer no - load test
1, the transformer no-load test power capacity of choice:
To ensure that the power waveform distortion does not exceed 5%, the test sample of the no-load capacity should be 50% of the power capacity; the use of pressure from the pressure, no-load capacity should be less than 50% of the regulator capacity; The no-load capacity should be less than 25% of the generator capacity.
2, no-load test is to measure the rated voltage under no-load loss and no-load current, test high side of the open side, low side pressure, the test voltage is low voltage side of the rated voltage, test voltage is low, the test current is rated current percentage A few or a few thousandths.
