ENR-DR series low voltage earthing resistance cabinet
Description: ENR-DR ow earthing resistance cabinet is the earthing resistance complete set device in 0.22KV~0.66KV low voltage system. In order to produce quality of 0.66/0.38/0.22 (KV) low voltage power supply and to reduce the equipments power off by the earthing fault caused. The power plant main plant low voltage power system should use the high resistance earthing. In this way not only avoid the immediately tripping when the single phase is earthing and and use fuse as the protector to reduce the probability of burn when the electrical equipments operation. Previously the low voltage system main uses the direct earthing or indirect earthing connection. When there has the single phase earthing fault, the neutral voltage direct remains constant which in the earthing system but the the current in the system is too big and it probability breakdown the insulation and burn the neutral system. If there is the indirect earthing connect then the over voltage which produced by the system is more than N times than the rated voltage. The phase voltage (except the fault phase) will rise several times because of Arc and ferromagnetic resonance Overvoltage and that will treat the insulation and stability of the power equipments. The "Mine electrical safety regulations " in our country provides that: Neutral point direct earthing transformers and generators are not allowed to direct supply power to the underground. In other words the Neutral point in the coal mine grid are not allowed direct earthing. Previously main use the Arc suppression coil earthing, but now we use the earthing resistance method follow up the technical change. After installed the neutral point earthing resistance cabinet, the current which flows the earthing point and neutral point significantly reduced when there occurs the non-metallic earthing. While the non fault phase voltage rises also significantly reduces and the zero-sequence voltage approximately 30% of single-phase metallic earthing. Features of products 1. Low voltage resistance earthing is made of stainless steel nickel-chromium alloy (Cr20Ni80) resistance, high conductivity, temperature coefficient α of 8.5 × 10 -5 ℃ (20-1100 ℃), high minimum temperature coefficient. Resistance can be resistant to 1500 ℃, toughness really deformation, corrosion-resistant. Resistance is very stable. 2. Low voltage resistance earthing can be used in variety low voltage distribution system and low voltage line which there is no neutral point and earthing transformer can be used in conjunction. It can curb the over voltage in the system and have a good effect to against various shocks. 3. Low voltage earthing resistance value is from 1Ω to 2000 Ω, the current is form 0.5A to 1000A. 4. The resistance cabinet can be used indoor or outdoor. The cabinet body is made of stainless steel cold-rolled steel plate or plastic spraying. 5. The earthing resistance cabinet can add the earthing recording and temperature humidity control device to record the device operation state.
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