MacLean Power Systems has launched the new “Bell Equivalent” insulator as a direct section length replacement for porcelain or glass bell strings.
The MPS polymer mold-on design is targeted at maintenance applications where insulators need to be the same length. This has been a design challenge for replacement polymer bell insulators 69kV and under. Traditionally, to achieve the same electrical and strength ratings of a porcelain insulator, the polymer insulator needs to be longer, which isn’t possible on existing lines.
The strength of the polymer insulator is achieved by crimping metal end fittings to the fiberglass core. These end fittings are approximately the length of one porcelain or glass disk causing that much shorter of a dry arcing distance, which is necessary for the electrical ratings of the insulator. MPS designed the new “Bell Equivalent” to overcome this length obstacle by molding the silicone housing over the end fittings, leaving just the socket and ball exposed for the connection to the conductor hardware and tower. By molding over the metal end fittings, the polymer insulator now has the same electrical properties and length as its porcelain counterpart.
Over the last 15 years, polymer has become the material of choice for insulators as nearly 80% of all new lines are built using polymer insulators. Polymer is approximately 80% lighter than porcelain and can be handled by a single lineman, which lowers installation costs and speeds up installation time.
Some of the benefits of using MacLean Power Systems’ Bell Equivalent insulators over porcelain or glass insulators include:
Installation right out of the box – eliminates the assembly of the individual bells of a porcelain string
Silicone housing has 20% more leakage distance – superior performance in contaminated environment
Corrosion resistant E-glass core – eliminates concern of brittle fracture failure
Higher mechanical strength – 25k SML v. 15k SML
The MPS Bell Equivalent insulators are packed in sets of 6 in cardboard containers that are stackable to minimize warehouse storage space. In addition to the cost savings from storage space, the polymer Bell Equivalent is more durable and will not break when jostled or dropped. Utilities no longer need to order extra quantities to cover possible handling damage.
MPS has always offered a complete line of polymer insulators for new transmission and distribution lines, but with the addition of the Bell Equivalent, we are able to further expand our maintenance and rebuild capabilities in the utility industry.