UHV-405kVA/270kV Cable Resonant Test Set

The UHV-405kVA/270kV series resonance scheme adjusts the power supply frequency to achieve resonance between the reactor and the test capacitor, thereby obtaining high voltage and large current on the test object. Due to its low required power supply, lightweight, and compact size, it has received widespread acclaim and application both domestically and internationally, representing a new method and trend in high-voltage testing.

The main functions and technical features of our company's frequency conversion resonance device are:

1, The device has protection functions such as overvoltage, overcurrent, zero-start, and system detuning (flashover). The overvoltage and overcurrent protection values can be set according to user needs. In case of a flashover, the flashover protection will activate and record the flashover voltage value for test analysis.

2, The entire device is lightweight, making it convenient for on-site use.

3, The device offers three working modes: fully automatic mode, manual mode, and automatic tuning with manual voltage boosting mode, allowing users to flexibly choose based on on-site conditions to improve testing speed.

4, It can store and remotely print data. The stored data is numbered digitally, making it easy for users to identify and search.

5, During automatic frequency scanning, the starting frequency can be set arbitrarily within a specified range, and the scanning direction can be chosen to be upward or downward. The large LCD screen displays the scanning curve, allowing users to intuitively understand whether the resonance point has been found.

6, Utilizing DSP platform technology, functions can be added or reduced, and upgrades can be made according to user needs, with a more user-friendly human-machine interface.

7, The required power supply capacity is significantly reduced. The series resonance power supply generates high voltage and large current through resonance between the reactor and the test object's capacitance. In the entire system, the power supply only needs to provide the active power consumed by the system, so the required power supply capacity is only 1/Q of the test capacity.

8, The weight and volume of the equipment are greatly reduced. In the series resonance device, the bulky high-power voltage regulator and conventional high-power frequency test transformer are eliminated. Moreover, the resonant excitation power supply only requires 1/Q of the test capacity, significantly reducing the system's weight and volume, typically to 1/10-1/30 of conventional test devices.

9, It effectively improves the output voltage waveform. The resonance power supply is a resonant filter circuit that can improve waveform distortion and obtain a good sine wave, effectively preventing harmonic peaks from causing mis-breakdown of the test object.

10, It prevents large short-circuit currents from burning the fault point. In a series resonance state, when the insulation weak point of the test object breaks down, the circuit immediately detunes, and the current rapidly drops to 1/Q of the normal test current. In contrast, when using parallel resonance or a test transformer for withstand voltage testing, the breakdown current immediately increases dozens of times. Compared to the two, the short-circuit current and breakdown current differ by hundreds of times. Series resonance can effectively find insulation weak points without the risk of large short-circuit currents burning the fault point.

11, No recovery overvoltage will occur. When the test object breaks down, the high voltage immediately disappears due to the loss of resonance conditions, and the arc extinguishes instantly. The process of re-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 will not result in any recovery overvoltage.

1. Extended Testing Capability: It can test 110kV/300mm² cables up to 0.5km (128kV test voltage) and perform full insulation tests on 110kV/120MVA main transformers (up to 160kV test voltage). This makes it suitable for high-voltage transmission class equipment.

2. Significant Weight and Size Reduction: Compared to traditional test transformers, the resonant design reduces the system's weight and volume to 1/10–1/30 of conventional equipment, greatly improving portability.

3. Low Power Supply Requirement: The power supply only needs to provide the active power losses (approximately 1/Q of the test capacity), allowing it to operate from a standard single-phase 220V or three-phase 380V supply.

4. Superior Safety: The resonant design inherently limits fault current to less than 1/Q of the normal test current during breakdown, preventing damage to the fault point and eliminating dangerous recovery overvoltages.

5. Excellent Waveform Quality: The low-distortion sinusoidal output (THD ≤1%) ensures reliable test results and protects the test object from harmonic-induced stress.

6. Proven Performance: The system's capability is verified with clear examples, such as testing 4.5km of 10kV/300mm² cable at 22kV for 5 minutes, or 2km of 35kV/300mm² cable at 52kV for 60 minutes.

1. AC Withstand Testing of High-Voltage Power Cables: It is particularly suited for testing 110kV XLPE cables, as well as longer runs of 10kV and 35kV cables.

2. AC Withstand Testing of Power Transformers: It can perform full insulation withstand tests on 110kV/120MVA class main transformers.

3. AC Withstand Testing of Switchgear: The system is applicable for testing 110kV voltage level switchgear and other electrical equipment, with test voltages up to 265kV.

4. Preventive and Handover Testing: It is designed for both periodic preventive maintenance tests and acceptance tests (handover tests) of high-voltage electrical equipment, complying with relevant standards like GB 50150-2016.