A Zero Sequence Current Sensor

Abstract

The invention relates to a zero-sequence current sensor and belongs to the zero-sequence current sensor technical field. The zero-sequence current sensor has the advantages of stable contact with a detection conductor, high transformation ratio of a coil, and high detection accuracy. According to the zero-sequence current sensor, at least two petal-type contacts form an annular iron core; the ironcore fixes one end of a conductor; the other end of the conductor is fixed by a support ring; the petal-type contacts of the zero-sequence current sensor are integrated with each other by means of welding; two ends of each petal-type contact are provided with fixing springs; eight petal-type contacts are adopted; and the turn ratio of the zero-sequence current sensor is 2000:1. The zero-sequencecurrent sensor of the present invention is applied to the user side of a power grid.

Description

technical field [0001] The invention relates to a zero-sequence current sensor, belonging to the technical field of zero-sequence current sensors. Background technique [0002] In the three-phase four-wire circuit, the phasor sum of the three-phase current is equal to zero. If an electric shock or leakage fault occurs in the circuit, there is leakage current flowing in the circuit, and the phasor sum of the three-phase current passing through the transformer is not equal to Zero, so there is an induced voltage in the secondary coil of the transformer. This voltage is added to the electronic amplifier circuit of the detection part, and compared with the current value of the predetermined action of the protection zone device, if it is greater than the action current, the sensitive relay will act. When the executive element is switched off, the transformer connected above is the zero-sequence current transformer. The phasor sum of the three-phase alternating current is not equa...

AI Technical Summary

Problems solved by technology

[0004] At present, the 10KV neutral point is widely used in the domestic power grid through the low-resistance grounding system. The zero-sequence protection device of the 10KV line in the substation and the switching station is used more and more in the form of an external zero-sequence current transformer. Due to the zero-sequence current transformer in the past There are not many uses, so many problems have been found in the installation and use, and some even cause the zero-sequence protection device to fail to operate when the ground fault occurs, and the protection is overstepped; the reason is that the current zero-sequence current sensor and the three Poor contact of the phase wires, single-point contact causes the detection end to be unstable. On the other hand, the structure of the 20:1 sensor currently used is likely to cause leakage of the magnetic force line due to the small number of coil groups. In order to reduce errors and improve accuracy, multiple sensors must be used. Group overlap structure, and this will inevitably result in bulky sensors and high cost

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