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Common Faults of Overhead Lines

Views:216     Author:Site Editor     Publish Time: 2020-11-26      Origin:Site


1. Fault classification

(1) Electrical short circuit fault. The first is the transient power short circuit fault of the line (usually the circuit breaker reclosing is successful); the second is the line permanent cable short circuit fault (usually the circuit breaker reclosing is unsuccessful).

 

Common types of short circuit: line metallic electric wire short circuit fault; line jumper disconnection arc short-circuit fault; drop-out fuse, isolating switch arc short-circuit fault; small animal short-circuits fault; lightning flashover short-circuits fault, etc.

 

(2) Ground short circuit fault. Including transient short circuit to ground fault of the line and permanent short circuit to earth fault of the line.


faults of overhead lines

 

 

2. Causes of failure

1 Metallic short circuit faults of the line include: ①Failure caused by external force damage, overhead line or pole equipment (transformer, switch) is short-circuited by external parabolic or external force scratched and short-circuited; car hits a pole to cause pole inversion or disconnection; typhoon or flood causes pole or disconnection. ②Line defects cause faults, excessive sag and typhoon will cause line hitting or electric force generated during power line short circuit.

 

(2) Line lead jumper wire disconnection arc short circuit fault: Line aging strength is insufficient to cause disconnection; line overload connector contact is poor, causing the jumper clamp to burn and disconnect.

 

3The arc short-circuit faults of the drop-out fuse and isolating switch include: ①The fusing of the drop-out fuse will cause the fuse to explode or arcing will cause a short circuit between phases; ②The circuit aging or overload causes the disconnector clamp to be damaged and burn out and arc to cause a short circuit between phases.

 

4 Short-circuit faults of small animals include: ①On the pier-type distribution transformer, the high-voltage down conductor from the drop-out fuse to the transformer adopts bare wires, and the transformer's high-voltage terminal and high-voltage arrester are not equipped with an insulating protective cover; ②The busbar of the high-voltage power distribution cabinet is not insulated, and the high-voltage power distribution room is not tightly guarded against rats;③In the high-voltage cable branch box, the bus bar is not insulated, and the cable branch box has leaks.

 

(5) Lightning overvoltage.

 

6 Transient ground faults of the line include: ①Single-phase grounding caused by man-made external throws or trees touching wires;

②The line insulators are dirty, and flashover to the ground occurs in rainy days or foggy and high humidity weather, which usually disappear after the weather improves or heavy rain.

 

(7) Permanent ground faults of the line include: ① Damage by the external force; ②Line isolation switch and drop-out fuse are caused by insulation aging and breakdown; ③It is caused by the explosion of the line arrester, which usually occurs in the thunderstorm season; ④ Direct lightning strikes cause the line insulators to burst, which usually occurs in thunderstorm seasons; ⑤ Caused by aging or defective breakdown of line insulators, it mostly occurs in coastal areas with serious pollution.


faults of overhead lines

 

In short, when the line fails, whether we can restore the power supply in the shortest time is the standard to measure the comprehensive technical quality of our power enterprise employees. The reliable overhead line fault passage indicator will help you find out the fault quickly without much human labor.


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