Overhead line Installation

Requirements for Overhead line Installation and knowledge of construction specifications

Aerial Bundled Cable and Overhead lines have the characteristics of low cost, easy to take materials, easy construction and easy maintenance.

Commonly used for long-distance transmission of electrical energy. The main components used in the overhead line are: conductors, surge arresters, insulators, towers and foundations, pulling lines, fixed fixtures.

General requirements for Overhead line Installation

· Steel-core aluminium stranded wire or aluminium stranded wire should be widely used for overhead lines.

The cross-section of aluminium strand of high voltage overhead line shall not be less than 50 square millimeters, and the cross-section of core aluminium strand shall not be less than 35 square millimeters; the cross-section of air line shall not be 16 square millimeters.

· Conductor cross-section should meet the needs of the maximum load.

· Selection of cross-section should also meet the voltage loss is not greater than 5% of the rated voltage (high-voltage overhead line),

or 2% ~ 3 (higher visual requirements of the lighting line). And should meet a certain mechanical strength.

· 1: High-voltage pole head, 2: High-voltage pin insulator, 3: High-voltage cross-arm, 4: Low-voltage cross-arm,

5: High-voltage suspension insulator, 6: Low-voltage pin insulator, 7: Cross-arm support, 8: Low-voltage butterfly insulator,

9: Chuck, 10: Chassis, 11: Pulling hoop, 12: Pulling top handle, 13: Pulling bottom handle, 14: Pulling disc;

Installation of Overhead line

The construction specification methods and steps of overhead line are as follows:

Line measurement: survey the terrain and features according to the design drawings, determine the starting point of the line, the corner point and the location of the poles in the terminal shop, and finally determine the location of the intermediate poles and the reinforcement poles and insert the marking stakes.

Pit excavator backfill: when excavating the pit, attention should be paid to the soil quality and the surrounding environment, the pit opening size is generally 0.8 metres wide and 0.3 metres long. The size of the pit opening for pulling wires is generally 0.6 metres wide and 1.3 metres long.

The reference values for the buried depth of the poles are shown in the table below: When backfilling the tower foundation and tie line foundation, it is not allowed to backfill tree roots, weeds and other things, the soil should be tamped more than twice, and the backfill should be 30~50 cm above the ground.

Poles: Electric poles are used to support Aerial Bundle Cable in overhead lines. There are many types of poles, and according to their roles, there are straight poles, corner poles, terminal poles and so on. Commonly used methods of pole erection are: crane pole, tripod pole erection, inverted fall type pole erection and foot pole erection.

Tripod pole is a relatively simple way to set up the pole, it mainly relies on a small winch on the tripod to hoist the pole, the pole will be moved to the side of the pit, set up a good tripod, in the end of the pole knotted three rope to control the pole, and then the pole will be erected to fall in the pole pit, and finally adjusted to the body of the pole, fill in the earth tamping.

Horizontal stretcher assembly: horizontal stretcher is installed insulators, switchgear, lightning arrester bracket.

According to the material, there are wooden cross stretcher, iron cross stretcher and ceramic cross stretcher.

Straight line pole cross stretcher should be installed in the load side, non-straight line pole should be installed in the tension counter side.

Insulators: Insulators are used to fix the wires. So it should have enough electrical insulation and mechanical strength.

The insulators commonly used in overhead lines are pin insulators, suspension insulators, butterfly insulators, etc.

Low-voltage insulators have a rated voltage of 1kV, while high-voltage insulators are used for 3kV, 6kV and 10kV lines.

Tension wire construction: the overhead line in the tension wire to support the role of the pole, general corner pole, terminal pole, tension pole, etc. must have a tension wire to support the pole, so as not to be tilted by the tension of the wire.

The general angle between the wire and the ground between 30 ° ~ 60 °, respectively, a good pull line on the handle, pull line in the handle, pull line under the handle.

Wire erection method: erection of wire including release, wire connection, hanging and tightening and so on.

Put the line is to put the wire from the disc to set up in the pole cross-arm. Release line has drag and drop method and show two kinds of release method.

Overhead line wire connection commonly used stranded, tied, crimped and so on. Hanging line is the wire with a small rope pulled up the pole, into the cross-arm.

Tightening is to tie the wire firmly to the insulator at the tension-resistant end and tighten it with a tight wire at the other end. Arc sag is the natural slack created by the sagging of the conductor within a stall distance.

The three-phase phase sequence of the overhead line should meet the following requirements: facing the load from the left side, the conductor arrangement phase sequence for Ll, N, L2, L3, the zero line is generally by the road side of the pole.

The poles are generally set up on the north and east sides of the road.

Construction requirements for household wiring: the household wiring is a section of overhead wire that leads from the pole of the overhead line to the first support point of the building.

· High and low voltage connection line should not cross the railway. Low-voltage connection line should not be from the high-voltage lead near the line.
· The distance between the house connection lines leading down from the pole tower should not exceed 30 metres. Distance between lines: 10kV and below should not be less than 0.5m, 0.5kV and below should not be less than 0.3m.
· Low-voltage household wires should use insulated wires, whose cross-section should be selected according to the safety current of the wires. The distance to ground should not be less than 2.5m.
· The vertical distance of the low-voltage connection line across the through street should not be less than 6 metres, and the special position should not be less than 3.5 metres.
· The distance between low-voltage connection line and weak power line crossing point should not be less than 0.6 metres.

Construction requirements for the house line: the house line is an insulated wire connected from the first outdoor support point to the first indoor support point. Its construction requirements are:

· The point of entry should not be lower than 2.7 metres, if it is too low, the entry pole should be installed.
· Into the house line using insulated wire, copper wire not less than 2.5mm2, aluminium wire not less than 10mm2, and into the middle of the line is not allowed to have a joint.
· Into the house line through the wall should be installed into the house casing, into the house casing wall thickness: steel pipe not less than 2.5mm, hard plastic pipe not less than 2mm, the pipe out of the wall part should be made waterproof elbow. The exposed part outside the house shall not be less than 6cm.

Xinfeng Cable manufacture overhead line. Such as Aerial Insulated Cable, Bare Conductors.  Our expertise in cable manufacturing extends to the production of Aerial Bundle Cables designed to meet the diverse needs of electrical infrastructure projects. Whether for low-voltage applications or high-voltage transmission, our commitment to quality, precision, and adherence to industry standards ensures that Xinfeng Cable delivers reliable and efficient Aerial Bundle Cables tailored to the specific voltage requirements of our clients.