Maintenance of power supplies is critical

Maintenance is always an issue when it comes to power supplies.

“The worst enemies of power supplies are dirt and grinding dust in the welding shop,” Jerry Begin, a contractor for The Lincoln Electric Co., said. Begin also worked for Lincoln Electric before he retired.

“Grinding dust gets sucked into the machines through the equipment’s ventilation system, with condensation, grease and other contaminants. If it’s not cleaned out, it can clog a system pretty good causing the power supply to shut down,” Begin said.

Most manufacturers, including Lincoln Electric provide a maintenance schedule for their equipment so that shops get maximum performance over the long haul.

However, depending on the shop environment, maintenance schedules can vary. For example, Begin said, power supplies in a foundry require more frequent cleaning than those in a regular fab shop because of the increased levels of heat and dust in a foundry.

In spite of the fact that power supplies need regular cleaning and maintenance, they usually don’t get it, Begin said.

“Most shops never pull maintenance on a machine until they need to fix it, then they clean it,” he added.

One solution that some shops try is to build a frame around the power supply, then put a furnace filter near the machine, but even those have to be changed frequently or the machine could shut down because its transformer shorts out.

Inverter technology is another answer.

Neal Borchert, business development manager for Miller Electric Manufacturing Co., said inverter-based welding and plasma cutting may provide the best return on investment for in-house plant maintenance and repair personnel, as well as the mechanical contractors that often perform this work.

“One contractor performing scheduled maintenance on a power plant calculated time saved to justify upgrading to inverter technology,” Borchert said, adding that the contractor was able to reduce labor time by 87 percent by using inverter technology.

Inverter technology allows shifting to a “rack” system that holds and powers multiple arcs from a primary connection. The inverters weigh less than traditional power supplies, and provide location flexibility.

One of the benefits of inverter technology with respect to maintenance and repair is the need for fewer machines.

“When a job requires both CC and CV processes, a CC/CV inverter means that there is one less machine to purchase or transport to the job site,” Borchert said.

However, with increasingly stringent OSHA restrictions and general air quality issues, most shops are cleaner than they were years ago, Begin pointed out. And, manufacturers are doing a better job of building power supplies mechanically tighter to prevent dust and dirt from entering the equipment and causing damage.

“On Lincoln machines, we use double sealed bearings so dirt doesn’t get into it. But there are a lot of our older machines out there -- up to 20 or 30 years old that still use a hand crank to change the output current – that require a lot of maintenance,” Begin said. “Also we find that now so many companies use robotics, they are much more concerned with cleanliness because the circuits in robots can’t stand dirt. Some are hardened for an industrial use but clean environments are much more the norm in companies with robots.”

Begin recommends that shops follow the recommended maintenance schedule at a minimum. “There are some large factories that are really involved in preventative maintenance programs in which the power supply equipment gets a periodic cleaning and inspection, and that’s really optimum.”