Variable Frequency AC Resonant Test Systems  | Detailed introduction of technical principles

The testing principle of variable frequency resonant equipment is to achieve series resonance by using a fixed inductor and adjusting the frequency, thereby efficiently generating high voltage.

The system consists of a variable frequency power supply, an excitation transformer, a fixed reactor, and a test specimen (equivalent capacitance) connected in series. The core advantage lies in the continuously adjustable output frequency of the variable frequency power supply (typically adjustable from 30-300Hz), while the inductance of the reactor and the capacitance of the test specimen are fixed.

During testing, the output frequency of the power supply is adjusted to precisely equal the inherent resonant frequency of the circuit determined by the fixed inductor and the capacitance of the test specimen. At this point, the inductive reactance and capacitive reactance are equal (XL=XC), the circuit achieves series resonance, the total impedance is minimized, and the current is maximized. Utilizing the voltage amplification effect (Q times) generated by resonance, a high-voltage sinusoidal wave with a well-defined waveform at power frequency (or near power frequency) can be obtained on the test specimen, significantly higher than the power supply output voltage, to complete the withstand voltage test. Its greatest advantage is that it allows for efficient on-site testing of large-capacitance test specimens such as cables and GIS using a small-capacity power supply and relatively lightweight equipment. Variable frequency AC resonant testing system, variable frequency series resonant test, variable frequency series resonant system 1000kVA 500kV 30-300Hz. This device is mainly designed and manufactured for AC withstand voltage tests of 35kV, 110kV, and 220kV cables, 110kV and 220kV switches, transformers, insulators, etc., and the neutral point of 220kV main transformers and the line terminals of 110kV main transformers.

It has a wide range of applications and is an ideal withstand voltage equipment for high-voltage testing departments at the prefecture, city, and county levels, as well as power installation and maintenance engineering units.

The device mainly consists of a variable frequency power supply, excitation transformer, reactor, capacitive voltage divider, and compensation capacitors.

1. 220kV and below circuit breakers, PTs, CTs, and insulators: test frequency 30-300Hz, test voltage 500kV, test time 1min

2. 110kV/630mm² cable, 1km, ≤0.201uF: test frequency 30-300Hz, test voltage 128kV, test time 60min

3. 110kV and below circuit breakers, PTs, CTs, and insulators: test frequency 30-300Hz, test voltage 270kV, test time 1min

4. 110kV main transformer terminals, capacitance ≤0.015uF: test frequency 45-65Hz, test voltage 160kV, test time 1min

5. 220kV/300mm² cable, 0.5km, capacitance ≤0.086uF: test frequency 30-300Hz, test time 60min

6. 35kV/630mm² Cable length 3km, capacitance ≤0.76uF, test frequency 30-300Hz, test voltage 52kV, test time 60min

1. Features overvoltage, overcurrent, zero-start, and system detuning (flashover) protection functions.

2. Equipment weight and volume are 1/10-1/30 of ordinary testing equipment. The power required for testing is only 1 Ω of the test capacity.

3. The device has three operating modes: fully automatic mode, manual mode, and automatic tuning/manual voltage boost mode.

4. Data storage and printing; stored data is numbered for easy user identification and retrieval.

5. The frequency starting point can be arbitrarily set within the specified range during automatic frequency sweep.

6. DSP platform technology; functions can be added, removed, and upgraded according to user needs; the human-machine interface is more user-friendly.

7. Improves output voltage waveform.

8. Prevents large short-circuit currents from burning fault points.

9. No recovery overvoltage will occur.

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MSXB-F-1000kVA 500kV Variable Frequency AC Resonance Test System, Variable Frequency Series Resonance Test, Variable Frequency Series Resonance System