What are the hazards of series resonance? Wuhan UHV specializes in the production of series resonance, with a wide range of product selection and professional electrical testing. To find series resonance, choose Wuhan UHV.
Series resonance utilizes resonant reactors and the capacitance resonance of the test sample to generate high voltage and high current, which is widely used for the handover and preventive testing of large capacity, high-voltage capacitive test samples such as power cables, power transformers, generator sets, motors, switchgear, GIS switches, etc. But there are also certain hazards hidden when using series resonance for voltage withstand testing. So, what are the hazards of series resonance? Below, we will explain the hazards of series resonance based on practical operational experience.
1. Conditions arising from series resonance
In a series circuit composed of resistors, inductors, and capacitors, when the capacitance reactance XC=inductance reactance XL is equal, series resonance occurs, and the phase of the voltage U and current I in the circuit are the same. When a series resonance occurs in a circuit, the impedance of the circuit Z=√ R2+XC-XL2=R, the total impedance in the circuit is the smallest, and the current will reach its maximum value. This may generate high voltages on inductors and capacitors that are many times higher than the power supply voltage, damaging the insulation of electrical equipment and affecting the safe operation of the power grid Properly adjusting the circuit parameters R, L, and C can avoid series resonance.
2. Measuring the characteristics of series resonant circuits
Quality factor is an important parameter for measuring the characteristics of resonant circuits. The larger the reactance and the smaller the resistance in a circuit, the higher the quality factor. Therefore, the voltage value on the capacitor or inductor will be much higher than the applied voltage. The quality factor values of general inductor and capacitor resonant circuits can reach tens or even hundreds. The harmfulness of resonant overvoltage is determined not only by its amplitude, but also by the duration. In the power system, series resonance will generate overvoltage several times higher than the rated voltage of the grid. Causing significant harm to the safe operation of electrical equipment.
In recent years, there have been multiple incidents of transformer damage in most parts of the country, mostly due to design and manufacturing reasons, as well as some incidents of ferromagnetic resonance caused by improper operation, resulting in PT explosions. Operation inspection shows that before designing the power grid, some ancient books and arrangements should be made to prevent the harm caused by series resonance or shorten the duration of resonance as much as possible.