WHAT IS A COUPLER?
Put simply a coupler is a large industrial version of the electrical plug and socket system you use in your home. While the plugs in your house use single phase power and have a power, neutral and ground contact; most industrial systems use a three phase system and include additional safety features due to the higher voltage and power draw. The result is that couplers have three power contacts, one or two ground contacts depending on the application, and up to four ground-check (pilot) contacts. The pilot circuit(s) is used to monitor the continuity of the ground wire from the power source to the end of the cable where the load is located. The pilot circuit is strictly a safety device, the pilot contacts within the coupler are designed to physically open before any others causing the breaker at a remote location to open. However the circuit is not designed to be used as a switch and the circuit breaker should be visibly open before operation of the coupler. Opening an energized coupler may result in injury to person or equipment.
HOW DO THEY WORK?
While a simple concept, couplers operate in tough conditions under the best of circumstances, making the design and testing required far more complex. While it is advised against, couplers are regularly exposed to and sometimes even submerged in water, dropped, dragged, and operated at voltage without proper maintenance. To protect against the physical stresses applied to the couplers they are housed in a thick aluminum shell that is fully grounded for safety. O-rings throughout and a TJB designed cable entrance allow for an IP67 weather rating. The couplers connect with large threads that are coated to prevent galling or a pin and slot design that TJB developed. The mechanical interconnection of the two couplers both prevents accidental disconnections and ensures the breaker has had time to trip before exposing the operator in the event of a disconnection under load.To ensure the electrical integrity of the insulators they are designed to withstand voltages much higher than those they operate at.
WHERE ARE COUPLERS USED?
The majority of TJB couplers are used in the mining industry, powering equipment in both surface and underground mines. Couplers are also used to connect large tunnel boring equipment to power in transportation, water management, and other infrastructure projects around the world. A growing market has been for coupler use in major ports of call, powering the large cranes that load and unload container ships and providing shore power to ships in an effort to reduce the environmental impact of their otherwise idling engines while moored. The rugged and self-contained design of couplers allows them to be used anywhere power needs to be delivered in a nonpermanent or mobile installation.