Transmission line fittings

Insulator strings for high-voltage overhead transmission lines provide the mechanical insulator system between the live conductors and the tower. The biggest share of the string is taken by the insulators, which are made of porcelain, glass or composite materials. The connecting elements, which are also called fittings in technical jargon, guarantee mechanical connection of all the components.

Tension clamps connect conductors to tension strings and withstand the required mechanical holding forces.

• A distinction is made between two types of tension clamps:
  • Disconnectable clamps, such as wedge tension clamps, bolted type tension clamps and helical dead ends with strain thimbles can be adjusted.
  • Compression dead end clamps, are permanent connections, and cannot be reopened to adjust the sag or tension adjustments.

Suspension clamps support and connect conductors onto insulator strings. Parallel groove clamps provide electrical connection between two conductors, and mainly used in jumper loops with wedge type tension clamps.

Due to laminar wind, overhead transmission lines will be excited to vibrations and oscillations that can lead to damage on the conductor of the overhead transmission line, single parts or  towers. In order to reduce these vibrations and oscillations to an uncritical dimension, damping systems will have to be installed in the overhead transmission lines.

The Stockbridge damper provides effective protection. Wind-induced vibrations can cause breakages on conductors. Here the Stockbridge damper counteracts. Inventor for this was George Stockbridge in 1924.

For Spacer Dampers in bundled lines, Mosodrfer is cooperating with DAMP s.r.l. (www.damp.it), a wholly owned Mosdorfer GmbH company and fully integrated into the Knill Energy group based in Austria Download Folder Damp

Overhead line spacers add reliability and protection to the conductor bundle, by separating conductors preventing clashing under operating conditions.

On tensioned overhead conductors, wind flow leads to high-frequency vibrations, with amplitudes in the magnitude of one conductor diameter. This is caused by vortex shedding, which excites the conductor into Aeolian vibrations at right angles to the wind direction.

Suitable vibration dampers prevent that fatigue stresses will damage the conductor, causing strand breakage and cable failure.

Arcing devices must fulfil two functions:

• Protecting against Corona effect
• Protecting the insulator from the effects of a power arc

Earthwires of overhead transmission lines will be usually fixed on top of the poles and primarily serve to protect the conductors from lightning and thus to increase operating safety because the necessity to shut off the facilities on short notice will be reduced.

Due to the trend towards central remote control and control of in-house facilities, such as power plants or substations, earthwires were successively being replaced by earthwires with integrated optical fibres. In addition, these OPGW (Optical Ground Wires) did not only serve for active lightning protection but also played an active role in data transmission.

For composite insulators, we manufacture fittings made of hot-dip galvanized steel or aluminum. Our range of products includes socket caps, ball caps, clevis caps, y-clevis caps and various other caps acc. to IEC 60120 and ANSI C29.2 as well as per customer specification. All the fittings are produced in-house.