The variable frequency series resonant withstand voltage test device adjusts the power frequency to achieve resonance between the reactor and the capacitance of the test object, thereby obtaining high voltage and high current on the test object, which is used to test the insulation performance of the equipment.
The variable frequency series resonant withstand voltage test device is based on the working principle of the series resonant circuit. When a capacitor and an inductor are connected in series, if the voltage across the capacitor and inductor is equal, the circuit will resonate, and the impedance of the circuit will be * small, and the current will reach * large value. In the experimental device, by adjusting the output frequency of the variable frequency controller, the inductance L of the reactor in the circuit and the capacitance C of the test sample are connected in series resonance, thereby obtaining the required voltage on the test sample. The specific process includes excitation circuit, voltage regulation, measurement and protection, etc. The voltage divider is connected in parallel to the test object to measure the resonant voltage on the test object and serve as an overvoltage protection signal.
The variable frequency series resonant withstand voltage test device usually consists of a variable frequency voltage regulating power supply, excitation transformer, reactor, voltage divider, and compensation capacitor. Variable frequency voltage regulating power supply is used to generate resonant output with adjustable frequency and adjustable voltage; The excitation transformer raises the voltage output by the variable frequency power supply to the appropriate test voltage; High voltage reactor is an important component of resonant circuit. When the power frequency meets specific conditions, it undergoes series resonance with the tested object; The voltage divider is connected in parallel to the test sample to measure the resonant voltage on the test sample and serve as an overvoltage protection signal.
Features:
The power capacity requirement is small. By utilizing the resonance between the resonant reactor and the tested capacitor, high voltage and high current are generated. In the entire system, the power supply only needs to provide the active consumption part, and the required power supply is only 1/Q of the test capacity (Q is the quality factor).
During the experiment, when the test sample breaks down, the system automatically loses resonance, avoiding secondary damage to the test sample; When the weak point of the insulation of the test sample is broken down, the circuit immediately becomes detuned, and the circuit current rapidly decreases to prevent short-circuit current from burning the fault point; When the test sample breaks down, due to the loss of resonance conditions, the high voltage immediately disappears and the arc immediately extinguishes, avoiding the occurrence of overvoltage recovery.
The equipment is small in size and light in weight. Due to the elimination of bulky high-power voltage regulating devices and ordinary high-power power frequency test transformers, coupled with a resonant excitation power supply that only requires 1/Q of the test capacity, the weight and volume of the system are reduced, generally by 1/10-1/30 of ordinary test devices, making it easy to transport and install on site.
Improvement of output voltage waveform. The variable frequency series resonant withstand voltage device is a resonant filtering circuit that can improve the waveform distortion of the output voltage, obtain a good sine waveform, help prevent harmonic peak from causing false breakdown of the test sample, and improve the accuracy and reliability of testing.