The series variable frequency resonant device is a complete set of equipment used for AC withstand voltage tests. It consists of a variable frequency power supply, excitation transformer, reactor, and capacitor voltage divider to form a series resonant circuit. This device is suitable for AC withstand voltage tests of power equipment such as cables, transformers, GIS, and generators, and can also be used for supporting tests of relay protection testers and related secondary equipment. Its working principle is to adjust the output frequency of the variable frequency power supply to make the circuit reach a resonant state, thereby obtaining the required high voltage on the test object.
The device adopts a modular design, and the reactors can be combined in series or parallel to adapt to test objects of different voltages and capacities. The variable frequency power supply has overvoltage, overcurrent, and overheating protection functions. The output frequency range is typically 20Hz to 300Hz, and the voltage waveform distortion rate is low. The system is equipped with a capacitor voltage divider for measuring the test voltage, and can realize automatic tuning, voltage boosting, timing, and voltage reduction through a microcomputer control unit. The operation interface provides real-time parameter display and fault alarms, facilitating monitoring by test personnel.
Rated capacity: customized according to test object requirements, common range 50kVA to 1000kVA;
Input power: three-phase 380V±10%, 50Hz;
Output frequency: 20Hz to 300Hz continuously adjustable;
Resonant voltage waveform: sine wave, distortion rate ≤1%;
Allowable continuous working time: ≤60 minutes under rated load;
Ambient temperature: -10℃ to +50℃;
Relative humidity: ≤90%RH.
This device is widely used in handover tests and preventive tests in fields such as power systems, industrial and mining enterprises, and scientific research institutes. Typical applications include: AC withstand voltage tests of 35kV and below XLPE cables, transformer induced withstand voltage tests, GIS combined electrical apparatus withstand voltage tests, generator stator winding AC withstand voltage tests, etc. At the same time, it can be used in conjunction with a microcomputer relay protection tester for complete set linkage tests of relay protection devices.
Before use, check that the equipment is reliably grounded and that the connecting wires are not loose. According to the capacitance of the test object and the test voltage requirements, calculate the required number of reactors and the connection method. After starting the variable frequency power supply, slowly adjust the frequency to the resonance point, then evenly increase the voltage to the specified value and start timing. After the test is completed, the voltage should first be reduced to zero, and then the power supply should be cut off. The equipment should be stored in a dry and ventilated place, and insulation checks should be carried out regularly.
