1660320840321 Article Whatworks1

Fast, safe reconfiguration boosts flexibility and efficiency

May 12, 2010
In this installment of What Works, Edison Welding Institute utilizes switch-rated plugs and receptacles for improved safety and efficiency.

Edison Welding Institute (EWI) in Columbus, Ohio, is dedicated to applied research and development of materials joining and welding. It provides expert materials joining assistance, as well as research, consulting and training to its members in the aerospace, automotive, government, energy, chemical, heavy manufacturing, medical and electronics industries.

Its 40,000-sq.ft. high-bay laboratory provides the space to set up individual work stations for a large number of projects simultaneously. Three 1,600 A bus bars provide 480 V power throughout the laboratory, with more than 100 separate power drops for welding power supplies.


Because of the nature of EWI’s assignments, workspace layouts and equipment are constantly being rearranged. “We have nearly every one of the recognized welding processes commonly used today, and they all require electricity,” says Andy Joseph, manager, welding and testing labs at EWI. “The equipment for these different procedures takes space, but we’re not using them all at the same time, so we need to be able to change them out.”

Previously, fused disconnects were attached directly to the overhead bus bars, with pin-and-sleeve connectors at the work stations. Safety was a concern because the disconnects were located at the ceiling level. Joseph explains, “We had to use a 20-foot pole with a hook on the end to turn off the power to a plug. Disconnecting live would have been an unsafe option.” From a safety standpoint, he adds, there was no way to disconnect quickly if someone was getting hurt.

Switch-rated plugs and receptacles make it safe and easy to connect and disconnect equipment such as the energy chain and mechanized welding system of this side-beam workstation.

As a remedy, EWI first considered installing disconnect switches at ground level for each location. This still would have required the pin-and-sleeve plugs to connect the equipment, and the switch boxes would have taken up valuable space. Joseph notes, “With 120 of the old connectors, we would have had to buy 120 disconnect boxes that would have required extra wiring.”

Instead, Joseph selected Decontactor Series switch-rated plugs and receptacles from Meltric (www.meltric.com), which combine the two functions. The decontactors were ordered from Johnson Electric Supply in Columbus. Now installed at more than 100 locations in the lab, the decontactors make disconnecting power a simple and safe operation. Pressing a pushbutton off-switch on the decontactor receptacle breaks the circuit and ejects the plug to its rest position. Then the plug can be withdrawn from the receptacle in complete safety, because the circuit is already dead. When the plug and receptacle are separated, deenergization can be verified visually and a safety shutter on the receptacle prevents access to live contacts.

Safety was the key factor in the decision to use the switch-rated plugs and receptacles. According to Joseph, simplified compliance to the NFPA 70E Standard for Employee Workplaces was an additional benefit. He says, “With the disconnects overhead, we would have had to suit up with personal protective equipment [PPE] because there was no way to verify that the power was disconnected without someone going up in a manlift. Having the disconnect switch right in the plug eliminates the need for an arc flash hazard assessment or suiting up.”

In addition to safety, the decontactors provide greater flexibility in EWI’s operations. Joseph points out, “We have a limited amount of space and are continually changing out equipment for different projects. When we start or finish a project, we can pull out one setup and bring in another quickly and safely.” Approximately half of the laboratories are set up for systems welding, with the other half divided between arc welding and laser welding. Joseph explains, “We might have to move one technology into another area, and the decontactors make that very simple.”

Another benefit, according to Joseph, is the easier installation of the decontactors compared to the pin-and-sleeve connectors. “They required soldering,” Joseph says, “and we’re constantly swapping equipment in and out. Changing the decontactors is a timesaver by comparison.”

In addition to the welding power supplies, EWI uses auxiliary equipment such as hoists, wire feeders, fume extractors, welding positioners, robotics and travel carriages. Joseph says he purchased 20 each of Meltric’s 20-A and 30-A decontactors for these applications, all rated for 480 V operation.

“Probably the biggest benefit for us has come from efficiency improvements,” Joseph says. “Previously, because of the difficulty with making disconnects during a changeover, we would leave workstations set up because it was hard to take them apart and put them back together. This made floor space hard to come by. It also caused some turf wars on how space was being used. Now, changeouts are easier to accomplish, we have a more presentable area and the engineers and technicians don’t have to worry about someone else tearing down their workstation because it is easy to set up again.”   

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