IMPROVE SAIDI & REDUCE WILD FIRE RISK – Covered MV ConductorSponsored
The covered single conductor forms the basis of all MV covered conductor systems. The covered conductor system, although not a touch-safe screened cable system, is designed to provide protection from initiation of flash-overs due to clashing of conductors, bird or animal incursions, and tree branches or debris which has blown or fallen on to the line, especially in conditions of severe weather and high pollution.
SPACER CABLE SYSTEMS are manufactured by Hendrix (USA) and distributed by Acculec in New Zealand and Australia. They are essentially three covered conductor phases in a close triangular configuration supported by a “messenger” or catenary cable. Hendrix Spacer Cable is used extensively in Canada, Sth America, the United States and in over 60 countries - including 3 Networks in New Zealand. There is increasing interest form Australian networks due to a lower fire risk profile than bare conductor.
Spacer cable is a pre-engineered electrical distribution system designed for high reliability, and improved right-of-way flexibility. The conductors are covered with three layers of polymer designed to allow intermittent contact with ground points (tree branches, etc.) without causing an outage or nuisance tripping. Covered conductors consist of stranded hard drawn aluminium conductors with either one, two or three extruded layers depending on the voltage rating. The system is now available for application on up to 66kV networks.
The conductor is supported by a high strength messenger (catenary) wire which provides mechanical support, a system neutral, and acts as a shield wire against lightning. The conductors are hung loosely beneath the messenger and supported by “spacers”, which results in virtually no tension on the conductors. The insulating properties of the covering allows the messenger and the conductors to be bundled into a compact area. The messenger wire is used as the earth of the system because of its high strength and high conductivity.
Since the spacer cable systems have a compact design that tolerates momentary contact, trees can be allowed to grow closer to the covered conductor than to bare wires while around coastal areas the system design limits the leakage current compared to bare conductor.
For more information on the design and features that will assist in your Networks’ SAIDI reduction and fire risk mitigation contact Acculec NZ.
Bruce Blundell
Acculec NZ
Email : sales@acculec.co.nz
P : 09 27404280
M: 021 427 774