Resonant test system UHV-75kVA/75kV

for electrical networksfor cablesfor transformers

Product Introduction
The UHV Frequency‑Conversion AC Series Resonant Test System is a modular, DSP‑based portable resonant test system for large‑capacity capacitance testing and preventive withstand‑voltage tests. It consists of an AC power source, excitation transformer, high‑voltage reactors and high‑voltage divider, and is engineered for on‑site deployment with multiple protection and operation modes.

Advantages of AC Resonant Test System for Cable in Power System Applications:

• Significantly Reduced Power Capacity Requirement: The series resonant power supply generates high voltage and large current through resonance between the resonant reactor and the capacitance of the test object. The power supply only needs to supply the active power losses of the system, meaning the required test power is only 1/Q of the total test capacity.
• Compact Size and Light Weight: In a series resonant power supply, bulky high-power voltage regulators and conventional power frequency test transformers are eliminated. Additionally, the resonant excitation power supply requires only 1/Q of the test capacity, reducing the overall system weight and volume to 1/10–1/30 of conventional test equipment.
• Improved Output Waveform: As a resonant filtering circuit, the power supply effectively reduces output voltage waveform distortion, delivering a clean sinusoidal waveform. This helps prevent false breakdown of the test object caused by harmonic peaks.
• Protection Against Fault Point Damage: In series resonance, when insulation breakdown occurs, the circuit immediately detunes, and the loop current drops rapidly to 1/Q of the normal test current. In contrast, during parallel resonance or test transformer-based withstand tests, the breakdown current increases by tens of times. This results in a short-circuit current that is hundreds of times smaller, allowing series resonance to effectively identify insulation weaknesses without the risk of burning the fault point.
• No Recovery Overvoltage: When the test object breaks down, resonance conditions are lost, causing the high voltage to disappear immediately and the arc to extinguish instantly. The recovery voltage re-establishes slowly over a long period, providing ample time to disconnect the power supply before the flashover voltage is reached again. This voltage recovery process is a prolonged, intermittent oscillation of energy accumulation, with no recovery overvoltage generated.

Technical Parameters

• Rated output voltage: 0~220kV(AC effective value) and below
• Output frequency: 30~300Hz
• Resonance voltage waveform: Pure sine wave, waveform distortion rate≤1.0%
• Full load working time: Continuous working time of 60min
• System quality factor: Under maximum load≥20
• Frequency adjust fineness: 0.1Hz
• Instability: ≤0.01%
• Working power supply: Single-phase 220V or three-phase 380V±10%,Power frequency 50Hz±5%

Product Characteristics

• 1、Due to the large number of cables used at voltage levels of 35kV and below, and the significant amount of testing work involved, a portable cable voltage withstand testing system has been developed, featuring a small size, light weight, and high portability.
• 2、This resonant test system requires that the weight of components that can be moved on-site by a single person should not exceed 30kg, and the weight of components that can be moved on-site by two people should not exceed 60kg, making it suitable for on-site handling.
• 3、The power supply adopts 220V single-phase power supply or 380V three-phase power supply, which is convenient for on-site power access.
• 4、The reactor part is made of dry epoxy casting, which is beautiful and reliable, suitable for various cable requirements.
• 5、For voltage withstand tests of cables with voltage levels of 110kV and above, oil-immersed reactors are used. When the single weight exceeds 100kg, our company's dedicated small electric crane can be optionally equipped.
• 6、The operation interface supports language switching, allowing for free switching between multiple languages. The default setting is switching between Chinese and English, and other languages can be customized.
• 7、The resonant test system is equipped with a built-in series resonance parameter calculator, which can quickly calculate the inductance, capacitance, frequency, resonance high-voltage current, and cable capacitance of series resonance with one click.

General Precautions for AC Resonant Test System for Cable

• 1. The series resonance test equipment should be used by high-voltage testing professionals. Before use, carefully read the user manual and undergo repeated operation training.
• 2. The number of operators for the series resonance device shall not be less than 2. During use, the safety operating procedures for high-voltage testing of the unit should be strictly followed.
• 3. To ensure the safety and correctness of the experiment, in addition to being familiar with the instructions for using the series resonant device, it is also necessary to strictly follow the relevant national standards and regulations for the test operation.
• 4. The wiring of each connector must not be connected incorrectly, otherwise it may damage the testing device.
• 5. When using a series resonant device, the output is high voltage or higher. Reliable grounding is necessary, and attention should be paid to operational safety.