Low-voltage grounding fault point locator and locating method

Abstract

The invention discloses a low-voltage grounding fault point locator and a locating method. A test power supply is used for applying alternate-current voltage between a fault line and the ground whichare isolated to form current, the flow direction of current passing through a grounding point is measured by an insulating pole type wireless alternate-current clamp ammeter; then the locator gradually approaches an unknown fault point in the flow direction of current passing through the grounding point, until the low-voltage grounding fault point is found. By the method, the fault point is searched by a test power supply through municipal power in a site. Due to the current limiting effect of the test power supply, no matter field grounding adopts high resistance or low resistance, the test instrument is not damaged even if the grounding is unstable, and the accuracy of the test can be ensured.

Description

technical field [0001] The invention relates to the technical field of finding fault points in low-voltage power systems, in particular to a low-voltage ground fault point finder and a search method for low-voltage ground fault points in low-voltage distribution networks. Background technique [0002] The neutral point of the 400V low-voltage power system is directly grounded. The advantage of direct grounding is that the three phases can supply power to customers separately, which improves equipment utilization and power supply reliability. However, due to the direct grounding of the neutral point, electric shock incidents are likely to occur. In addition, due to the large resistance value of the direct grounding of the neutral point, the short-circuit current is small when the phase line is short-circuited to the ground, and in most cases is less than the rated current of the transformer. Low-voltage current-type protection such as fuses, electromagnetic air switches, etc...

AI Technical Summary

Problems solved by technology

However, due to the direct grounding of the neutral point, electric shock incidents are likely to occur. In addition, due to the large resistance value of the direct grounding of the neutral point, the short-circuit current is small when the phase line is short-circuited to the ground, and in most cases is less than the rated current of the transformer. Low-voltage current-type protection such as fuses, electromagnetic air switches, etc. cannot operate correctly, resulting in the long-term existence of phase-to-ground short circuits, neutral point voltage displacement, and zero-line electrification. If it is low, it cannot be used normally, and if it is heavy, there will be an electric shock casualty accident

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