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Variable Frequency Series Resonant Test System

type:ZCVF-A 1000kVA-400kV

This Series resonant test system mainly targets 10kV, 35kV, 110kV, and 220kV cables; 220kV/240MVA main transformer fully insulated; Design and manufacture of AC withstand voltage tests for 110kV and 220kV GIS, switches, and circuit breakers. The reactor adopts multiple separate designs, which can meet the requirements of high voltage and low current equipment testing conditions, as well as low voltage AC withstand voltage testing requirements such as 10kV cables. It has a wide range of applications and is an ideal withstand voltage equipment for local, municipal, and county-level high-voltage testing departments and power installation and repair engineering units.The device mainly consists of a variable frequency control power supply, excitation transformer, reactor, and capacitor voltage divider.


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  • Product Introduction

This Series resonant test system mainly targets 10kV, 35kV, 110kV, and 220kV cables; 220kV/240MVA main transformer fully insulated; Design and manufacture of AC withstand voltage tests for 110kV and 220kV GIS, switches, and circuit breakers. The reactor adopts multiple separate designs, which can meet the requirements of high voltage and low current equipment testing conditions, as well as low voltage AC withstand voltage testing requirements such as 10kV cables. It has a wide range of applications and is an ideal withstand voltage equipment for local, municipal, and county-level high-voltage testing departments and power installation and repair engineering units.The device mainly consists of a variable frequency control power supply, excitation transformer, reactor, and capacitor voltage divider.


  • Product Parameters
Rated output voltage
22kV - Meet the AC withstand voltage test of 10kV cables; Working frequency: 30-300Hz, Test voltage 22kV, test time 5min
52kV - Meet the AC withstand voltage test of 35kV cables; Working frequency: 30-300Hz, Test voltage 52kV, test time 60min
128kV - Meet the AC withstand voltage test of 110kV cables; Working frequency: 30-300Hz, Test voltage 128kV, test time 60min
216kV - Meet the AC withstand voltage test of 220kV cables; Working frequency: 30-300Hz, Test voltage 216kV, test time 60min

300kV - Meet the AC withstand voltage test of 110kV GIS, switches, and circuit breakers; Working frequency: 30-300Hz, test voltage not 

exceeding 265kV, test time 1min

400kV - Meet the AC withstand voltage test of 220kV GIS, switches, and circuit breakers; Working frequency: 30-300Hz, test voltage not 

exceeding 395kV, test time 1min

200kV - Meet the AC voltage withstand test for full insulation of 220kV240MVA main transformer; Working frequency: 45-65Hz, test voltage 

not exceeding 160kV, test time 1min

Output voltage waveform distortion rate<1.0%
Permissible continuous working time60 minutes of one-time operation under rated conditions
Quality factor of the device itselfQ ≥ 30 (f=45Hz)
Device output waveformsine wave
Input power supplythree-phase 380V or single-phase 220V
Frequency adjustment range30Hz~300Hz
System measurement accuracy1.5%
Variable frequency power supply (one set)
Rated power30kVA
Input voltagethree-phase 380V or single-phase 220V ± 5% 50Hz
Output voltage0-400V adjustable
Output voltage frequency30-300Hz  0.1Hz step adjustable
Frequency instability≤ 0.02%
Output current0-75A
Excitation transformer (one set)
Rated capacity30kVA
Input voltage400V
Output voltage1.2/2.5/5/10/20kV
Output current25/12/6/3/1.5A
High voltage reactors (ten in total)
Rated working voltage40kV
Rated working current2.5A
Rated inductance37H
Continuous working time60min
Temperature riseless than 65k
Working frequency30-300Hz
Capacitor voltage divider (one set)
Self capacitance500pF
Rated voltage400kV
Working frequency30-300Hz
Uncertainty1.5%
Rated voltage400kV/500pF
One set of testing lines


  • Product Features

Advantages of applying series resonant test system in power systems:

1. The required power capacity is greatly reduced. 

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

2. The weight and volume of the equipment are greatly reduced. 

In the series resonant power supply, not only does it eliminate the bulky high-power voltage regulating device and ordinary high-power power frequency test transformer, but also the resonant excitation power supply only needs 1/Q of the test capacity, greatly reducing the system weight and volume, which is generally 1/10 of the ordinary test device.

3. Improve the waveform of the output voltage. 

Resonant power supply is a resonant filtering circuit that can improve the waveform distortion of the output voltage, obtain a good sinusoidal waveform, and effectively prevent the accidental breakdown of the test object caused by harmonic peaks.

4. Prevent large short-circuit currents from burning fault points. 

In the series resonance state, when the insulation weakness of the test object is broken down, the circuit immediately becomes de tuned, and the circuit current rapidly drops to 1/Q of the normal test current. When conducting voltage withstand tests using parallel resonance or test transformers, the breakdown current immediately increases by tens of times, and 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 worry of large short-circuit currents burning fault points.

5. There will be no recovery overvoltage. 

When the test object experiences breakdown, due to the loss of resonance conditions, the high voltage immediately disappears, the arc immediately extinguishes, and the process of establishing the recovery voltage is long, making it 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 cause any recovery overvoltage


The main functions and technical characteristics of our company's frequency modulation resonance device:

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

2. The entire device is lightweight and easy to use on site.

3. The device has three working modes, making it convenient for users to flexibly choose according to on-site conditions and improving 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 number is a number, which is convenient for users to identify and search.

5. When the device automatically scans the frequency, the starting point of the frequency can be arbitrarily set 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 easy for users to intuitively understand whether to find the resonance point.

6. Adopting DSP platform technology, it is convenient to add or remove functions and upgrade according to user needs, and also makes the human-machine exchange interface more user-friendly.


  • Product Video

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