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Switch-Rated Electrical Plugs for Quarry Equipment

By Mark S. Kuhar

Meltric Decontactor Series switch-rated plugs and receptacles are specifically designed to provide superior performance in the harsh environments common to the mining, quarry and aggregate industries for a wide variety of process equipment including feeders, conveyors, pumps, crushers, stackers, generators, motors and other equipment.

Central to their performance and durability benefits is switch-rated plug technology, which consists of an integral, spring-loaded disconnect constructed with silver-nickel, butt-style electrical contacts.

The spring-loaded disconnect eliminates the contact mating and connection quality problems intrinsic to sliding-friction contacts, such as pin-and-sleeve, twisting-lock and blade types, because the quick make-and-break mechanism minimizes arcing and contact pitting, and the consistent spring pressure compensates for manufacturing variations as well as overheating caused by poor contact force.

The silver-nickel, butt-style contacts are configured in end-to-end contact mating arrangement to eliminate the effects of wear and cold welding that is inherent with sliding friction contacts. A special design feature of the butt-style contacts is a self-cleaning, wiping motion that occurs as the contacts close. The silver-nickel contact material is used because it withstands heat, oxidation and arcing much better than standard brass contacts. In addition, silver-nickel performs well in wet and corrosive environments.

The combination of the silver-nickel material and the spring-loaded, butt-style contacts provide an ideal contact technology for plugs repetitively opened and closed under load. Meltric Decontactor switch-rated plugs have been performance tested to provide more than 6,000 trouble-free operations under full load. They meet the performance test requirements for UL 1682/CSA C22.2 No. 182.1 and the UL Subject 2682 standard for switch-rated plugs and receptacles.

Meltric Decontactor switch-rated plugs and receptacles eliminate arc flash risks with a genuine dead-front design. Dead front construction eliminates potential exposure to arcing and unintended access to live parts, and the removal of the plug from the receptacle provides verification of de-energization. In this type of dead-front design, load making and breaking occurs within enclosed arc chambers.

In addition, before the plug can be removed from its receptacle, a safety shutter closes over the receptacle’s contacts so miners are shielded from “live” parts and can have no exposure to arc flashes during or after the plug is removed. Thus, electrical connections can be made and broken without the need to establish flash hazard boundaries, perform voltage testing, or “suit-up” to meet NFPA 70E’s PPE requirements for energized electrical work.

Decontactor plugs and receptacles are UL and CSA rated for “motor circuit” and “branch circuit” disconnect switching. The switch-rated technology eliminates the need for costly mechanical interlocks and offers several other advantages: high amperage ratings up to 200 amps; an exclusive dead-front design that blocks access to live contacts; spring-assisted terminals that withstand vibrations; standard provisions to make lockout simple; optional auxiliary/pilot contacts to control or monitor equipment without the need for secondary connectors; and short circuit ratings that allow it to successfully close into and withstand short circuit currents of up to 100kA when used in circuits protected with RK1 fuses.

Decontactor switch-rated plugs and receptacles are constructed with reinforced polyester or zinc-aluminum alloy casings to provide excellent impact resistance as well as protection against UV radiation and harsh chemicals. Rugged housings are rated up to NEMA 4X or IP66 + IP67. Optional accessories are available that allow them to be mounted on walls, boxes, panels or in-line. Meltric plugs and receptacles are backed with a five-year warranty on the electrical parts.
Meltric Corp,