When MPS acquired Dulhunty Power Systems in 2012, there were several items that Dulhunty produced for their market that MPS did not offer in the United States market. Products, such as formed wire, were implemented shortly after acquiring Dulhunty. Formed wire was an easy adaptation to the American market because the product matched dimensions and adhered to specifications for both markets. Other products, such as helical suspension clamps, needed dimensional and strength rating changes to successfully offer the product to the American market.
Helical Suspension Clamps for Transmission Lines
Helical suspension clamps are made to provide support for overhead conductor, while minimizing bending strain caused by Aeolian vibration. Aeolian vibration is caused by wind blowing across a conductor. This causes the conductor to vibrate. Aeolian vibration is harmful to conductors because, as the conductor is vibrating, bending strain is being applied to each conductor strand. Depending on conditions, this prolonged vibration causes strand breakage and reduces the conductor’s strength and can cause hot spots to occur. Standard conductor support devices support the conductor, but the abrupt manner where the conductor exits the clamp causes minimal reduction of bending amplitudes at the exit point.
Helical suspension clamps have a large rubber grommet and armor rods that support the conductor, and provide a more controlled transition from the support structure to the rest of the span. This gives the customer another option for their suspensions, and provides additional protection against Aeolian vibration damage.
The new MPS Helical Suspension Clamps have redesigned bodies for increased vertical loads seen in American markets.
Vibration Dampening Products
MPS has recently introduced several new products for vibration dampening. The products designed for specifically dampening vibration are helical vibration dampers, Stockbridge dampers, and spacer dampers.
Helical vibration dampers are used to dampen vibration in smaller conductor wires, shield wires, OPGW, ADSS, and guy spans. The number of spiral dampers placed per span is an important factor in the effectiveness of the damper. Generally, the longer the span, the more spiral dampers are required.
Stockbridge dampers are designed for use on bare conductor, over armor rods or line guards, and on static wire. Stockbridge dampers are designed for use on a single conductor. There are over 25 clamp and weight variations. The damper is “tuned” to the specific conductor it is clamped to based off the conductor’s resonant frequency, and the conductor’s diameter. As the conductor begins to vibrate, the damper also vibrates. The energy of the vibration is dampened by dissipating the energy into the messenger wire on the damper. The damper is designed to withstand many million cycles of vibration without failing, while providing protection against Aeolian vibration on the conductor for many years. Selection of the damper, along with how many dampers are used, and placement on the conductor, are based off line conditions. Span length, conductor tension at varying temperatures, and other factors are loaded into software specifically designed for damper selection and damper placement. MPS’s software is used to give the utility directions on how many are needed, and where to install the dampers depending on span lengths and line conditions.
Spacer dampers are similar to Stockbridge dampers, but are used on multiple, bundled conductors. The spacer dampers are dual purpose, providing dampening protection, while also maintaining spacing on a span length. The spacing is typically 18″, and is available for two, three, four, and six conductor bundles.
Helical Vibration Damper