The series resonance test device (power frequency withstand voltage device) is mainly designed and manufactured for AC withstand voltage testing of electrical main equipment such as 10kV, 35kV cables, 35kV main transformers, busbars, switches, insulators, etc. The series resonance test adopts multiple separate designs, which can meet the requirements of high voltage and low current equipment testing conditions, as well as the requirements of low voltage AC withstand voltage testing such as 10kV cables. It has a wide range of applications and is an ideal withstand voltage equipment for high voltage testing departments and power installation and maintenance engineering units at the prefecture, city, and county levels. The device mainly consists of a variable frequency control power supply, excitation transformer, reactor, and capacitive voltage divider.

1. The series resonance test device has protection functions such as overvoltage, overcurrent, zero position start, and system detuning (flashover). The overvoltage and overcurrent protection values can be set according to user needs. When the test sample flashover, the flashover protection action can be taken and the flashover voltage value can be recorded for test analysis.

2. The entire device is lightweight, with a maximum weight of no more than 40kg, making it easy to use on site.

3. The series resonance test device has three working modes, which facilitate users to flexibly choose according to the on-site situation and improve the test speed. The working modes are: fully automatic mode, manual mode, and automatic tuning manual boost mode.

4. It can store and print data in different locations, and the stored data numbers are numerical, making it convenient for users to identify and search.

5. The frequency starting point of the series resonance test device during automatic frequency scanning can be set arbitrarily within the specified range, and the scanning direction can be selected upwards or downwards. At the same time, the LCD screen displays the scanning curve, making it convenient for users to intuitively understand whether the resonance point has been found.

6. The series resonance test device adopts DSP platform technology, which can easily add or remove functions and upgrade according to user needs, and also makes the human-machine exchange interface more user-friendly.

7. Series resonant power supply generates high voltage and high current through resonance between resonant reactor and the tested capacitor. In the entire system, the power supply only needs to provide the active consumption part of the system. Therefore, the required power supply for the experiment is only 1/Q of the test capacity.

8. In a series resonant power supply, not only is the bulky high-power voltage regulating device and ordinary high-power power frequency test transformer eliminated, but the resonant excitation power supply only requires 1/Q of the test capacity, greatly reducing the system weight and volume, usually 1/10-1/30 of ordinary test devices.

9. Improve the waveform of the output voltage. A resonant power supply is a resonant filtering circuit that can improve the waveform distortion of the output voltage, obtain a good sine waveform, and effectively prevent the accidental breakdown of the test sample by harmonic peaks.

10. Prevent large short-circuit currents from burning the fault point. In the series resonance state, when the weak point of the insulation of the test sample is broken down, the circuit immediately loses resonance, and the loop current rapidly drops to 1/Q of the normal test current. When conducting voltage withstand tests using parallel resonance or test transformer methods, the breakdown current immediately increases by several tens of times. Compared to the two, the short-circuit current and breakdown current differ by hundreds of times. So, series resonance can effectively identify insulation weaknesses without the concern of large short-circuit currents burning the fault point.

11. There will be no overvoltage recovery. When the test sample breaks down, due to the loss of resonance conditions, the high voltage immediately disappears, the arc immediately extinguishes, and the process of re establishing the recovery voltage is long. It is easy to disconnect the power supply before reaching the flashover voltage again. This voltage recovery process is an intermittent oscillation process of energy accumulation, which is long and does not result in any recovery overvoltage.