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YDQ Gas-Insulated Test Transformer
Gas-filled AC test transformers are crucial for inspecting and testing power equipment, especially as voltage requirements become more demanding. Traditional oil-immersed transformers no longer meet size, weight, and performance needs for fieldwork. The introduction of SF6 gas, with its superior insulation, arc-extinguishing properties, and non-flammability, has revolutionized power equipment. The YDQ series gas-filled AC test transformers are 20%-60% lighter, eliminate oil pollution, and reach voltage levels up to 300kV, making them ideal for fieldwork and frequent relocations.
Structure
- The YDQ series products feature entirely new design concepts, material selections, and manufacturing processes. Therefore, they are not only small in size, lightweight, and aesthetically pleasing, but also meet all technical specifications of the DL/T848.2-2004 standard.
- The YDQ series products utilize high-quality cold-rolled DQ-151 oriented silicon steel sheets stacked into a multi-stage cylindrical frame core. High-voltage tower coils are directly and continuously wound using QZ-type conductors on a specially designed high-strength insulating cylinder. The outer shell is conformally sized and filled with SF6 gas.
- The YDQ(JZ) product differs from the YDQ product in that it cleverly integrates the high-voltage rectifier silicon stack within the high-voltage sleeve. By inserting and removing the short-circuit rod, the YDQ can be switched between power frequency high-voltage AC output and high-voltage DC output.
- The YDQ(C) product differs from the YDQ product in its internal sleeve structure.
Working Principle
The power input is fed into the control box, which features an overcurrent automatic tripping device and a zero-position interlock to prevent sudden voltage increases. The voltage is then regulated by an autotransformer and input to the primary winding of the YDQ gas-filled AC test transformer. Based on the principle of electromagnetic induction, a voltage amplitude—a power frequency high voltage—can be obtained in the secondary (high voltage) winding according to the ratio of its turns to those of the primary winding. This power frequency high voltage is then rectified by a high-voltage silicon stack and filtered by a voltage-stabilizing capacitor to obtain a DC high voltage, the amplitude of which is twice the effective value of the power frequency high voltage.
Control circuit diagram
Technical Specifications and Parameters
- Voltage Rating: 10kV～300kV
- Capacity Range: 1～500kVA
- No-load Current: <7%
- Impedance Voltage: <8%
- Product Type: AC, AC/DC, AC cascade, AC/DC cascade
Operating Conditions of Gas-Insulated AC Test Transformers
1. Under rated operating conditions, the YDQ gas-insulated AC test transformer should meet the following requirements:
1) Ambient temperature: -20℃ to +40℃
2) Relative humidity less than 85%.
3) The installation location should be free from gases, vapors, chemical dust, dirt, and other explosive media that could seriously affect the transformer’s insulation.
4) When using the YDQ gas-insulated AC test transformer, the input voltage should be gradually increased, and a sufficient protective resistor should be connected in series at the output terminal. Never disconnect or reconnect the equipment under high voltage conditions.
2. Permissible Operating Time of the Transformer
Under-rated capacity and rated voltage, continuous operation should not exceed half an hour. The time interval between each operation should be 5-10 times the operating time to ensure sufficient heat dissipation of the transformer. Long-term continuous operation is permitted under two-thirds of the rated voltage and rated current.
