QLD-270kVA108kV

 Test Scope Requirements:

• AC withstand voltage test for 5km of 10kV/300mm² cable: capacitance ≤1.8775uF, test frequency 30-300Hz, test voltage 22kV, test time 5min.
• AC withstand voltage test for 2km of 35kV/300mm² cable: capacitance ≤0.389uF, test frequency 30-300Hz, test voltage 52kV, test time 60min.
• AC withstand voltage test for 35kV switches and other electrical equipment: test frequency 30-300Hz, test voltage not exceeding 95kV, test time 1min.

Main components of the device

Main Functions and Features

The UHVXZ series variable frequency series resonant withstand voltage test device uses the method of adjusting the power supply frequency to make the reactor and the capacitor under test resonate, thereby obtaining high voltage and large current on the test object. Due to its low power requirement and light weight and small size, it has been widely praised and applied at home and abroad, and represents a new method and trend in high voltage testing.

Technical Features

•  The device features overvoltage, overcurrent, zero-point start, and system detuning (flashover) protection functions. Overvoltage and overcurrent protection values ​​can be adjusted according to user needs. In the event of flashover, the flashover protection activates and records the flashover voltage value for test analysis.
• The entire device is lightweight, facilitating field use.
• The device offers three operating modes: fully automatic, manual, and automatic tuning/manual voltage boost mode. Users can flexibly choose the mode according to site conditions, improving test speed.
• It can store and remotely print data. Stored data is numbered for easy identification and retrieval.
•  During automatic frequency sweeping, the starting frequency can be set arbitrarily within a specified range, and the sweep direction can be selected upwards or downwards.
• Simultaneously, a large LCD screen displays the sweep curve, allowing users to intuitively understand whether the resonant point has been found.
•  Utilizing DSP platform technology, functions can be added, removed, or upgraded according to user needs, resulting in a more user-friendly human-machine interface.
•  The required power supply capacity is significantly reduced. A series resonant power supply utilizes the resonance between a resonant reactor and the capacitance of the test object to generate high voltage and large current. In the entire system, the power supply only needs to provide the active power consumed by the system; therefore, the power required for the test is only 1/Q of the test capacity.
•  Significantly reduced equipment weight and size. The series resonant device eliminates the need for bulky high-power voltage regulating devices and ordinary high-power power frequency test transformers. Furthermore, the resonant excitation power supply only requires 1/Q of the test capacity, greatly reducing the system weight and size, typically to 1/10-1/30 of ordinary test equipment.
•  Effectively improves the output voltage waveform. The resonant power supply uses a resonant filter circuit, which can improve the waveform distortion of the output voltage, obtaining a good sine waveform and effectively preventing harmonic peaks from causing false breakdown of the test object.
• Prevents large short-circuit currents from burning out fault points. In series resonance, when the insulation weakness of the test specimen is broken down, the circuit immediately detunes, and the loop current rapidly drops to 1/Q of the normal test current. However, when using parallel resonance or a test transformer for withstand voltage testing, the breakdown current immediately increases by tens of times. The difference between the short-circuit current and the breakdown current is hundreds of times. Series resonance can effectively locate insulation weaknesses without the risk of large short-circuit currents burning the fault point.
•  No recovery overvoltage will occur. When the test specimen breaks down, the high voltage disappears immediately due to the loss of resonance conditions, the arc is extinguished instantly, and the re-establishment process of the recovery voltage is very long. It is easy to disconnect the power supply before the flashover voltage is reached again. This voltage recovery process is an intermittent oscillation process of energy accumulation, which is long and does not result in any recovery overvoltage.

Main Technical Parameters

•  Rated Capacity: 270kVA
•  Rated Voltage: 27kV; 54kV; 108kV
•  Rated Current: 10A; 5A; 2.5A
•  Measurement Accuracy: System RMS 1.5 grade
•  Operating Frequency: 30-300Hz
•  Output Waveform: Sine wave
•  Quality Factor: Device’s own Q≥30 (f=45Hz)
• Waveform Distortion Rate: Output voltage waveform distortion rate ≤1%
•  Input Power Supply: Single-phase 220V or three-phase 380V voltage, frequency 50Hz
•  Operating Time: Allowable continuous operation for 60 minutes under rated load; 1 minute under 1.1 times overvoltage
•  Temperature Rise: Temperature rise ≤65K after 60 minutes of continuous operation under rated load
•  Protection functions: Overvoltage, overcurrent, zero-position start, system detuning (flashover) protection, etc.
•  Ambient temperature: -20℃ to 55℃
•  Relative humidity: ≤90%RH
•  Altitude: ≤3000 meters