The main purpose of transformer no-load test is to measure no-load current and no-load loss, analyze their variation patterns, discover local or overall defects in the magnetic circuit, and discover winding defects. The precautions for transformer no-load test include:
1. The test should be conducted at the rated tap, and the applied voltage is required to be a sine waveform and rated voltage at the rated frequency.
2. When conducting rated no-load tests on three-phase transformers, the test power supply should have sufficient capacity.
3. The test voltage should be kept stable. When using the three-phase power supply method for testing, it is required that the three-phase voltage is symmetrical, that is, the negative sequence component does not exceed 5% of the positive sequence component, and the three-phase line voltage difference does not exceed 2%. If the three-phase power supply does not meet the requirements, the single-phase power supply method can be used for testing.
4. When wiring, it is necessary to pay attention to the polarity of the current coil and voltage coil of the power meter. The indication of the power meter may be positive or negative.
5. During the no-load test, the polarity of the transformer must be connected correctly, with the primary and secondary connections corresponding to each other, and the secondary terminals corresponding to the polarity of the meter. It should also be noted that the transformer should have a secondary terminal for safe grounding. For three-phase transformers or three single-phase transformers, the same terminal and grounding point should be used for grounding. The current circuit should be securely connected to prevent interruption during the testing process.
6. In order to ensure accurate measurement results, the connecting wires should have sufficient cross-sectional area, with current wires not less than 2.5 square meters and voltage wires not less than 1.5 square meters, and good contact. When the loss of the tested transformer itself is small, the measured loss value should be subtracted from the loss of the test instrument itself.
7. During the phase separation no-load test of a three-phase transformer, do not connect it to the transformer casing during a short circuit.
8. During the experiment, if abnormal readings are found on the meter or if the tested transformer has abnormal conditions such as discharge sound, abnormal noise, smoke, or oil spray, the power supply should be immediately disconnected to stop the test, identify the cause, and take appropriate measures. Otherwise, the test cannot continue.
9. Low voltage no-load test should be conducted before insulation resistance measurement and leakage current measurement. If residual magnetism is believed to exist in the tested equipment during the experiment, demagnetization must be carried out to eliminate the influence of residual magnetism on the test results.
The ZC-202B transformer capacity and no-load tester is a new type of instrument developed and designed by our company specifically for the problem of poor power users evading basic electricity bills and increasing capacity without authorization. It is used as a high-precision instrument for measuring characteristic parameters such as transformer capacity, no-load, and load. This instrument is a multifunctional measuring instrument, equivalent to two traditional testing instruments: transformer capacity tester and transformer characteristic parameter tester. It can accurately measure a series of power frequency parameters such as capacity, type, no-load current, no-load loss, short-circuit (load) loss, impedance voltage, etc. of various transformers. This product has many advantages such as small size, light weight, high measurement accuracy, good stability, and simple operation. It can completely replace the traditional method of measuring transformer loss and capacity using multiple meters, with simpler wiring, more convenient testing and recording, greatly improving your work efficiency.
Kvtester Electronics Technology Co.,Ltd. is a high-tech enterprise specializing in power testing, testing, research and development, production, and sales of testing equipment. It has been engaged in the electrical testing industry for many years, and its products are of high quality. We welcome customers to come and purchase. Service hotline: 0086-27-81778799, to learn more, visit the official website: www.kvtester.com
