Overhead cable design principles and fault prevention measures

Common types of overhead cable faults

1. Single-phase fault

Single-phase ground fault is the most common of the distribution system and occurs in damp, rainy weather. Single-phase ground not only affects the user's normal power supply, and Hunan Sunshine Electronic school maintenance experts think it: Maybe overvoltage burned equipment, or even cause a short circuit and phase expansion of the accident. In the event of a phase (eg phase A) is not completely grounded through high resistance or arcing ground, then the lower voltage fault phase, the phase of the non-fault voltage increases, and the phase voltage are greater than, but does not reach the line voltage. If A phase completely grounded occurs, the fault voltage drops to zero with the non-fault phase voltage raised to the line voltage.

When looking for and handling single-phase faults, should take safety measures to ensure personal safety. When the device is on the ground, the indoor body from the point of failure can not be close to within 4 m, outdoor may not be close to the point of failure from within 8 m, into the above-mentioned range of staff must wear insulated boots, wear insulated gloves, use of special tools.

2. Short-circuit fault

Two lines of different potentials to be a conductor shorted together or insulation during the breakdown, resulting in failure of the line does not work, called short-circuit fault. In accordance with the difference, the short circuit fault is divided into a metallic short circuit, non-metallic short circuit; single-phase short circuit and multi-phase short circuit.

3. Circuit fault

Breaker is the most common fault, and the most basic form of expression is a circuit failure. In some cases, breaking also causes over-voltage trip point arc is also generated from Hunan Sunshine Electronic school maintenance experts believe: may cause electrical fire and explosion.

Common Cause overhead cables

Single-phase ground fault cause

Single-phase ground fault occurs in damp, rainy weather, is due to the tree barrier, single-phase power distribution line insulator breakdown, wire joints overload or oxidative corrosion blown off, single-phase and other factors caused the break.

1. Short-circuit Cause

- External damage

- Lightning

- Bird damage

- Lines, the equipment itself reason

2. Failure trip

- External damage

- Lightning

- Lines, the equipment itself reason

Overhead cable Fault precautions

1. Single-phase ground fault prevention measures

Timely pruning of the tree line where the obvious contradiction between the trees.

Lightning protection measures were taken to reduce the lightning caused by the single-phase fault. In addition, in order to reduce the surface of the insulator and porcelain skirt inner product contamination or poor manufacturing quality moisture after rain, and flashover discharge, resulting in a ground fault occurring in the line construction (reconstruction) must choose qualified, good quality of insulators, and pressure test prior to installation, ensure the installation quality.

In the peak load, the use of an infrared thermometer to measure the temperature of the wire joints, once found abnormal temperature, treated immediately, to avoid the heat fuse wire.

2. Short-circuit fault prevention measures

Measures to prevent external damage

In order to reduce vehicle collision accidents tower, try to migrate the tower, it can not migrate suspended striking the reflective paint brand in the tower, to cause the vehicle driver's attention.

Prohibition is set to take eye-catching signs, print leaflets, etc. to strengthen publicity and education, in order to prevent the kite, color, etc., causing a short circuit fault.

Strengthening and municipal garden department associates and timely pruning affect the safe operation of the trees.

Seeks to obtain with the local police, and the public security department, the development of effective prevention measures and specific programs to strengthen efforts to combat the theft of 10 kV line tower destroyed materials and fittings and other electrical installations.

Operational department regular visits to check the foundation towers 10 kV line, cable-based and illegal building, the foundation of the tower, cable-based emptied of timely repair of defective and maintenance of the equipment in time for the illegal buildings to be sorted out.