A method for detecting grounding faults of bridge cables

Abstract

The invention relates to a detection method for a cable grounding fault. A method for detecting a grounding fault of a bridge cable, which includes: connecting one end of the faulty cable to the output end of a DC stabilized power supply, and the other end to be short-circuited to any other intact phase cable; connecting the output end of the DC stabilized power supply to the other The other end of any phase cable; turn on the DC stabilized power supply to keep the output current stable at 5-10A; use a DC voltmeter to measure the values ​​V1 and V2 of the voltage range of the two ends of the faulty cable to the bridge frame; The rough position of the fault point of the cable can be calculated; then the DC stabilized power supply is released, and one end of the resistance gear of the multimeter is connected to one end of the faulty cable, and the other end is grounded; the insulating rope is used to trap the faulty cable near the rough measurement position and move. When the resistance value of the multimeter points to the maximum value, that is, the position where the insulating rope moves is the fault point. The invention can be used for fast and accurate detection of the grounding fault point of the cable laying bridge.

Description

technical field [0001] The invention relates to electrician detection, in particular to a detection method for cable grounding faults. Background technique [0002] For a long time, many measurement methods and instruments have emerged for cable fault detection. These methods and instruments are suitable for different fault situations and have their own advantages and disadvantages. Domestic and foreign literature introduction and practical application are compared and evaluated as follows. [0003] 1. Cable fault location [0004] (1) Bridge method: This is a classic test method. Since the cable DC resistance is proportional to the length, the distance to the fault point can usually be calculated by measuring the proportional relationship between the cable fault point and the resistance value of the measurement end and end. [0005] The advantages of the bridge method are simplicity, convenience, and high accuracy. [0006] The disadvantage of the bridge method is that ...

AI Technical Summary

Problems solved by technology

[0014] The advantages and disadvantages of the pulse current method are similar to the pulse voltage method

[0015] 2. Directly buried cable fault fixed point

[0021] In practical applications, when there are ferromagnets around the cable or at the cable joint, the received signal is often stronger, so it is difficult to measure the ground fault by using the audio induction method, and the fault point is often not found

[0022] 3. Fixed point of exposed cable fault

However, this method requires the inspector to directly contact the live cable, which is less safe.

[0036] Based on the above analysis, the current shortcomings in the detection of cable ground fault points mainly include: the use of the bridge method is affected by the resistance; the pulse method and the acoustic measurement method require high voltage, and sometimes the test time is long; The audio method has problems such as environmental interference; the local overheating method and the current detection method have problems such as electric shock and blindness; the eccentric magnetic field requires special equipment and personnel, and has large limitations.

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