Resistance-grounded system

Abstract

The invention belongs to the technical field of electricity, discloses a resistance grounding system, and particularly relates to an automatic control resistance grounding system. One end of a neutral-point isolating switch is connected with one end of a neutral-point current transformer, the other end of the neutral-point isolating switch is connected with one end of a power transformer, the other end of the neutral-point current transformer is connected with one end of a thyristor which can be opened and closed, the other end of the thyristor which can be closed is connected with a neutral-point grounding resistance, the other end of the power transformer is connected with a voltage transformer, and two triangle ends of a secondary opening of the voltage transformer is connected with the relay for controlling the opening and closing of the neutral-point thyristor. The automatic control resistance grounding system improves the reliability of medium-voltage power distribution, prevents the occurrence of cable fires, and can be widely applied in 3 to 35kV industrial enterprises and city network power distribution systems.

Description

technical field [0001] The invention belongs to the technical field of electricity and discloses a resistance grounding system, in particular an automatic control resistance grounding system. Background technique [0002] With the rapid development of the current national economy, in order to meet the needs of industrial and agricultural production and people's daily life, my country's power generation facilities and urban network power supply and distribution facilities have also developed by leaps and bounds. Among them, the neutral point grounding method of 3-35kV industrial enterprises and urban network power supply and distribution is one of the important and key issues related to the safe power supply of medium voltage system power supply and distribution. At present, in cable-based industrial enterprises and urban network medium-voltage power supply and distribution systems, it is the general trend to adopt the resistance neutral point grounding method. The medium-vol...

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Problems solved by technology

[0003] The disadvantage of the neutral point resistance grounding system is: before the grounding fault is eliminated, the potential around the grounding fault is increased. If timely tripping measures are not adopted, it will cause insulation breakdown of the equipment and endanger people's lives; For intermittent grounding and metal grounding, although 20-30% of the grounding current value is taken, sometimes it cannot be judged very accurately; due to manufacturing, actual use will cause three-phase imbalance problems, generally up to 10-20% So there is a 10-20% unbalanced so-called zero-sequence voltage on the neutral point resistance

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