By hvhipot 
HV Hipot Electric Co., Ltd. specializes in producing series resonance (also known as power frequency withstand voltage tester). Next, we will share with you an introduction to the fHV Hipot Electric Co., Ltd. voltages that series resonance can withstand.
The insulation structure of electrical equipment can withstand the following fHV Hipot Electric Co., Ltd. voltages during operation:
1. The insulation structure of electrical equipment must be able to withstand the maximum working voltage of the power frequency for a long time during the entire operation process, usually referred to as the maximum working voltage of the system, which is generally 1.15 times the rated voltage.
2. Transient overvoltage, including rising frequency voltage and resonant overvoltage. The increase in resonant AC power frequency voltage of the series resonant withstand voltage test device is caused by the capacitance effect of the no-load line, load shedding, and asymmetric grounding. When the load suddenly unloads, due to the fact that the power supply only has one unloaded transmission line, and the grounding reactance of the transmission line can be represented by X0, the current flowing through the internal resistance of the power supply becomes capacitive current. This current flows through the reactance in the system, causing an increase in voltage. Due to the boost of nearly 50 Hz AC voltage, it is a rise in power frequency voltage. Under the current relay protection, its action time is about tens of milliseconds to one second. With the long-term application of AC voltage, it has a significant impact on the insulation aging of electrical equipment and the insulation structure of power systems. Resonant overvoltage is caused by resonance caused by ferromagnetic effect or nonlinear inductance components of the iron core. Its amplitude is higher and its duration is longer. Its frequency can be the fundamental frequency of the power frequency or higher-order harmonics.
3. Overvoltage operation is caused by the operation of circuit breakers in the power system. In a series circuit composed of resistors, inductors, and capacitors, when capacitor XC and inductor XL are equal, the phase of voltage U and current I in XC=XL is the same, and the circuit is resistive. This phenomenon is called series resonance. When a series resonant circuit is used, such as cutting off or closing a long no-load line, cutting off an unloaded transformer (pneumatic variable), etc. This overvoltage waveform is very irregular and the situation varies greatly. It can be an attenuated oscillation wave or a non periodic voltage shock wave, typically reaching maximum voltage within 1ms. The overvoltage of power system operation is related to the system voltage. The higher the system voltage, the lower the voltage. The voltage of 6-35 kV system is about 5-4 times higher.
4. Lightning overvoltage often causes insulation damage to electrical equipment. In order to ensure the safe operation of the power system, lightning protection measures must be taken, such as installing lightning rods, lightning arresters, etc. In order to ensure that the insulation structure can withstand the above fHV Hipot Electric Co., Ltd. voltages, it is necessary to conduct shock wave voltage tests and power frequency voltage resistance tests on the insulation structure, and the insulation structure must have sufficient margin. The capacitors of the sample and the reactor form a series resonant connection mode, and the voltage divider is connected in parallel to the tested object to measure the resonant voltage of the test object and serve as an overvoltage protection signal.
In order to ensure that the insulation structure can withstand the above fHV Hipot Electric Co., Ltd. voltages, it is necessary to conduct shock wave voltage tests and power frequency voltage resistance tests on the insulation structure, and the insulation structure must have sufficient margin. The capacitors of the sample and the reactor form a series resonant connection mode, and the voltage divider is connected in parallel to the tested object to measure the resonant voltage of the test object and serve as an overvoltage protection signal.