The quality of cast voltage transformers depends on the excitation characteristic test.
2022-05-30
Casting voltage transformer The quality depends on the excitation characteristic test. The excitation characteristic of the equipment is actually the magnetization curve of the iron core, because the test mainly looks at the open circuit of the primary winding, the relationship curve between the secondary excitation current and the applied voltage, and the quality of the iron core is judged according to the fullness of the curve, and whether there is a short circuit between the turns of the winding. The excitation characteristic test also reduces the occurrence of iron core resonance overvoltage and poor quality of voltage transformers in the power system, which is very necessary.
Analysis of the excitation characteristic test of cast transformers separately. For cast voltage transformers, the volt-ampere characteristic test should first remove the secondary winding leads and grounding wires of the component, and perform a one-time open-circuit test, applying voltage from the secondary side. The applied current or voltage should comply with the manufacturer's technical specifications. For easy reading, several current points can be selected for testing during the test, and the measured voltage values can be read point by point. When the current becomes larger and the voltage change is small, the iron core is full, and the test can be stopped. Then, the volt-ampere characteristic curve is drawn according to the readings. For cast voltage transformers, the no-load excitation characteristic test requires the high-voltage side to be open-circuited, and the low-voltage side to be externally applied voltage to read its no-load current and no-load loss. Generally, the no-load excitation characteristic test can be carried out together with the power frequency induced voltage withstand test. When the voltage rises to the additional voltage, several sets of no-load loss and no-load current values are read first. When the voltage rises to 0.3 times the additional voltage and lasts for 40 seconds, the no-load loss and no-load current values are read after dropping to the additional voltage or below.
Casting voltage transformer Various performance tests can use a volt-ampere characteristic tester, which is a multi-functional field testing instrument specifically used for testing volt-ampere characteristics, ratio, error curves, withstand voltage tests, etc. The instrument does not need to connect an external standard transformer during operation. By presetting the test voltage/current value, it displays the volt-ampere characteristic curve or ratio change, polarity, and other test results, and can actively increase the voltage/current. Then print it out with a printer. It avoids various cumbersome operations such as manual voltage adjustment and manual recording during the experiment, and also avoids errors caused by manual operation. Cast voltage transformers can be applied to various types of transformer equipment, which is very convenient.
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