The working principle of the frequency conversion transformer comprehensive tester is mainly based on frequency conversion technology and low-frequency measurement principle. The following is a detailed explanation of its working principle:
1. Principle of Frequency Conversion Technology
The comprehensive tester for variable frequency transformers utilizes variable frequency technology to test transformers by changing the power frequency. According to Faraday's law of electromagnetic induction, the magnetic flux of the iron core is proportional to the induced voltage at both ends. When the test frequency is reduced, the induced voltage generated by the same magnetic flux will also decrease proportionally. Therefore, by reducing the test frequency, applying a lower voltage can make the transformer core reach saturation state. This frequency conversion technology significantly reduces the required voltage for testing, thereby improving the safety and efficiency of testing.
2. Principle of Low Frequency Measurement
① CT testing principle:
In the case of an open circuit on the primary side of CT, apply voltage from the secondary side and measure the relationship curve between the applied voltage V and the input current I. This curve approximates the relationship between the excitation potential E and excitation current I of CT.
Assuming that the excitation inductance of the CT excitation winding is L and the excitation impedance is Z at a certain excitation current I, the relationship between voltage V and current I can be expressed as V=I • Z. The relationship between inductance L and impedance Z is Z=ω • L=2 π fL, therefore V=I • 2 π fL. It can be seen that at a certain excitation inductance L, the applied voltage V is proportional to the frequency f.
For example, when f=50Hz, the required voltage Vx to achieve the excitation current Ix may be 2000V; while when f=50Hz, the required voltage drops significantly to about 200V.
② PT testing principle:
The comprehensive tester for variable frequency transformers also uses low-frequency method to test the excitation characteristics of PT. By reducing the testing frequency, PT can be tested at lower voltages, thereby avoiding excessive voltage stress on the equipment.
3. Testing process
① Set test parameters: Set test parameters on the computer, including test frequency, test voltage, test mode, etc.
② Sending test signal: The signal generator generates a test signal, which is sent to the transformer after the frequency is changed by the frequency converter.
③ Collecting response signals: The sampler collects the response signals of the transformer and sends them to the computer for processing.
④ Calculate transformer parameters: The computer calculates various parameters of the transformer based on the collected data, such as transformation ratio, leakage, short-circuit impedance, etc.
⑤ Display test results: The computer displays the test results on the screen and can save the test data.
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
