By hvhipot 
Q: What are the methods for the series resonant withstand voltage test of transformers?
Answer: There are two common methods for series resonant withstand voltage testing of transformers:
(1) Inductive series resonant withstand voltage test. The adjustable inductor L is connected in series in a high-voltage circuit. When adjusting the reactor to WL1/WCX=, the voltage drop across the reactor is numerically equal to the voltage drop across the capacitor, and the circuit reaches a resonant state, generating a high frequency voltage on the tested object.
(2) Variable frequency series resonance withstand voltage test. When the frequency converter is connected to the test power supply, the power frequency can be adjusted within the range of 30-300hz. When the output voltage frequency of the frequency converter cabinet reaches the resonance condition, that is, f=1/(2 π√ LC), a resonant high voltage will be generated on the test object. If the reactor combination and capacitance are adjusted simultaneously, the test frequency can be controlled within the frequency range of 45-65fhz, and most can be controlled within the frequency range of 49-51 hz. Due to the convenience of adjusting equipment to reach vibration free points, it is currently widely used on site.
Q: What are the precautions for transformer series resonance withstand voltage test?
Answer: When conducting a series resonant withstand voltage test on transformers, attention should be paid to:
(1) Tuning should be performed before boosting. When using a series resonance test device, the test voltage frequency should not be lower than 40Hz, and the full voltage withstand time should be 60s. During the test, the inductance or frequency should be tuned under low excitation voltage to find the resonance point. When the voltage on the test object reaches its highest point, which is the resonance point of the test circuit, the boost test can begin.
(2) The quality factor Q value of the resonant testing circuit is related to the dryness and cleanliness of the testing equipment and the insulation surface of the testing object, as well as the diameter and length of the high-voltage leads. Therefore, the test should be conducted on clear weather. The insulation surfaces of testing equipment and test objects should be dry and clean. Try to shorten the length of high-voltage leads as much as possible and use large-diameter high-voltage leads to reduce corona losses. Improve the quality factor Q value of the testing circuit.
HV Hipot Electric Co., Ltd. specializes in the production of series resonance (also known as variable frequency resonance test device), engaged in the electrical measurement industry for many years. Its products have first-class quality and welcome customers to come and purchase.