Overhead transmission line insulator parallel gaps (hereinafter referred to as the parallel gap, also calls the arcing horn) lightning protection at the core of the thought is in the range of allowable lightning trip-out rate, the clearance between device and insulator (string) in parallel, lightning flash flipping, gaps in the channel power frequency arc, protect the insulator from arc burning, improve the success rate of reclosing.This standard specifies the relevant technical conditions, test methods, installation, operation and maintenance for the clearance performance of insulators in parallel.In order to reduce the impact of the parallel clearance on the lightning trip rate of transmission lines, an insulator may be added to the insulator (string) while the parallel clearance is installed. At the same time, whether the air clearance at the tower head and the cross crossing distance meet the requirements of relevant standards can be considered.

Working principle of clearance in parallel connection of an insulator

Lightning protection principle of insulator parallel clearance is as follows: parallel metal electrodes (also known as arc angles) at both ends of the insulator () form a protective parallel clearance, and the distance of the parallel clearance is usually less than the length of the insulator (string).When an overhead transmission line is struck by lightning, the lightning impulse discharge voltage of the parallel clearance is lower than that of the insulator (string), and the parallel clearance first discharges.Under the action of electric power and thermal stress, the connected power-frequency arc is led to the electric extreme part of the parallel clearance through the discharge channel formed by the parallel clearance, and the arc root is fixed in the electric extreme part of the parallel clearance, so as to protect the insulator from arc burning.

 Product Installation

Check the appearance before installation.In order to avoid rework and correct installation, pre-assembly can be carried out before climbing the tower. Check whether there is any problem in connection between electrodes and various kinds of gold fittings in advance, and determine the installation location of each part by referring to the assembly drawing.

After installation of the insulator parallel clearance, the actual distance of the clearance shall be measured to confirm that it meets the technical parameters and shall be recorded.

The upper and lower arc angles should be on the same level.

The mounting bolts shall be fixed reliably to ensure the reliable connection between the parallel clearance electrodes and the fittings.Electrical conductivity is good.

Check the electrical conduction performance between overhead wires and power fittings, and between the pole tower cross arm and power fittings. If it does not meet the requirements, new power fittings should be replaced.

Installation diagram

1. The parallel clearance shall be installed on a single dangling porcelain (glass) insulator string

2. The parallel clearance is installed on the insulator string of the single overhanging composite jacket

3. The parallel clearance shall be installed on a single tension-resistant porcelain (glass) insulator string

Physical installation drawing of parallel clearance

Operation and Maintenance

The operating unit shall establish insulator parallel clearance files.

2. Main contents of patrol inspection: whether there is ablative trace of insulator parallel clearance electrode and whether there is abnormal in parallel clearance.

3. If there is an ablative trace on the insulator parallel clearance electrode during patrol inspection, it shall be judged as parallel clearance flashover. Observe whether the insulator has flashover trace, and it is appropriate to take photos and record.

4. If the electric extreme part of the parallel clearance is found to increase the clearance distance by more than 5cm due to repeated cauterization during patrol inspection, it shall be recorded and replaced when the line is regularly repaired.

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