GDTF-4500/750 is specially designed for AC withstand voltage test for 500kV or below switch, GIS, instrument transformers and neutral point of main transformers. The system includes variable frequency power supply, exciting transformer, reactor, and capacitive voltage divider.
Advantages in the power system application: 1. Small power of required power supply. The power source of series resonance uses the resonant reactor and test object capacitance to generate high voltage and high current. In the whole system, the power supply only needs to supply the part ofactive loss. Therefore, required test power is the 1 / Q of test capacity. 2. Light weight and small size. In the series resonant power supply, it does not use heavy high-power voltage regulators and traditional high-power power frequency test transformers. The resonant excitation power supply only needs 1/Q of the test capacity, which greatly reduces the weight and volume of the system, generally 1/10-1/30 of traditional test equipment. 3. Good waveform of output voltage. Resonant power source is resonant filter circuit, which improves the distortion of output voltage waveform and obtain good sine wave. It greatly prevents the test object from breakdown of harmonic peak. 4. High short-circuit current will not burn the fault point. In the status of series resonant, when the test object insulation weakness is breakdown, circuit detune immediately, and the loop current rapidly drop to 1 / Q of normal testing current. While tested by parallel resonant or testing transformer, the breakdown current rise dozens of times immediately. Therefore, testing by series resonant can find the insulation weakness effectively and high short-circuit current will not burn fault point. 5. Any recovery overvoltage is not appeared. When the test object breakdown, the resonance will be disappeared and high voltage also disappear immediately, arc extinguish at once, and the time of recovering voltage is long, it will disconnect power supply before reaching the flashover voltage. The voltage recovery process is a kind of energy accumulation of intermittent oscillation, the process is long, and any recovery overvoltage will not be appeared.
Compliance standard <Electrical equipment installation project electrical equipment handover testing standards>GB50150-2006 <High voltage resonance test device> DL/T849.6-2004 <Reactor> GB10229.88 <Electricity equipment preventive testing regulations>DL/T596-1996 <Coupling capacitors and capacitance voltage divider> IEC358 (1990) < High voltage test techniques> IEC60060
II. Features
1. With the protection function of over-voltage, over-current, zero-start, system detune (flashover). Over-voltage, over-current protection value can be set accordingly to user's need. Flashover protection starts when flashover and the flashover voltage value will be recorded for testing analysis. 2.The unit piece of the device is light, suitable for field use. 3.There are three kinds of working mode for user choosing according to on-site condition. Automatic mode, Manual mode, Automatic tuning manual boosting mode. 4. Data can be stored, and the storeddata No. are figures which is easy for identification and searching. 5. Frequency starting point can be set in the specified scope when the device sweep frequency automatically, sweep frequency direction can be selected upward or downward, meanwhile LCD displays the scanning curve, which is convenient to know if the resonant point found or not intuitively. 6. With DSP technology, which can increase or decrease functions and updated accordingly to the user's need, it also makes the human-machine interface more friendly.
III.TechnicalSpecifications
GDTF - means manufacturer's code. 4500kVA means the maximum rated capacity of the equipment, the unit is kVA 750kV means the output voltage of the equipment, the unit is kV.
Output voltage waveform distortion rate: <1.0%.
Allowing continuous working time: one-time 5mins at rated value.
Quality factor of the equipment: Q>50
Quality factor of making test for firepower generator: Q>10 (Related with load).
Quality factor of making test for power cable: Q>30 (Related with load)
Quality factor of making test for main transformers: Q>30 (Related with load)
Quality factor of GIS, circuit breakers in full load test: Q > 50 (Related with load)
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