MacLean Power Systems formula suspension clamps are designed to support ACSR and all aluminum conductors without the use of armor rod. Meaningful savings in both material and installation labor can be realized by eliminating the need for formed armor rod. The formula suspension concept is simple: formula clamps offer the conductor substantially increased support areas in order to reduce bearing loads on the underside of the conductor. This support prevents early failure by protecting the strands on which the conductor rests.
When EHV transmission lines were first built, they introduced longer spans, heavier conductors and often higher sag tensions. The industry quickly realized that these line designs required a larger support area at the conductor attachment to prevent damage to the individual AL strands. Strands at the bottom surface of the conductor are subjected to radial bearing loads. Care in the clamp design must be taken to prevent loads from exceeding the compressive yield points at the strand crossings. Excessive compressive loads on the conductor cause strands to nick each other where they cross and the damaged strands are then subject to early failure even under less than severe conditions.
Armor rod has been successfully used to protect the conductor from damage. With the addition of armor rod, the outside diameter at the conductor attachment point is increased, which requires a larger suspension clamp with larger grooves, greater length and, as a consequence, a greater support area. The armor rod solution does have significant cost impact. Typically, armor rod cost two to three times the price of the suspension clamp and additionally it takes at least 15 minutes to install for each conductor attachment.
By increasing the length of the suspension clamp and designing its bend radius to mimic the sag of the line, the MPS formula suspension clamp can be used to safely and securely attach the conductor without the additional expense or installation time of adding armor rod to all aluminum and ACSR conductors. This translates to significant project savings.
Formula suspension clamps can also be applied for other applications. By adding armor rod to high temperature conductors, the formula clamp can be used with high temperature, ACSS conductors up to the full rated 250°C without exposing the clamp body to annealing temperatures. Formula clamps can also be supplied for higher mechanical ratings, up to 50 kip, for use on heavy angle assemblies.