Team Industries Cashes In On Energy Efficient Inverter Technology

By: Neal Borchert, account manager, Miller Electric Mfg. Co.

Whose advice on boosting energy efficiency can be more trustworthy than that of the local power utility? When Kaukauna Utilities suggested that Team Industries, Inc. evaluate its equipment’s energy efficiency to save money, the Kaukauna, Wis.-based piping and tank fabricator complied. Starting in March 2001, Team began replacing aging, power-hungry welding machines with efficient inverter-based welding power sources from Miller Electric Mfg. Co. 

Team’s investment will result in a $303 annual electricity savings per power source and a $413 rebate per power source from Kaukauna Utilities. Team also stands to save thousands of dollars per year in maintenance costs through improved reliability. Perhaps most importantly, Team has invested in its own future by guaranteeing a consistently superior product.

Energy Efficiency

“About a year ago, after considering Kaukauna Utilities’ recommendations, we made a commitment to look at our equipment needs and what would be required to sustain us over the next 15 years. Obviously, energy cost was a high priority issue,” says Donald J. Murphy, president of Team Industries. “We knew that welding machine technology had changed greatly, so we wanted to invest in this technology, particularly the newer energy-efficient power sources. But we also wanted machines that were operator- and maintenance-friendly, along with multi-process capability. The bottom line was how to perform the same amount of work using less energy.”

Kaukauna Utilities seeks to foster this mind-set among its customers. “Saving energy is a win-win proposition for us and the customer,” says James J. Brown, Kaukauna Utilities’ customer service representative and a consultant to Team and other industrial customers.

“Our philosophy is to work with customers to ensure they use energy as efficiently as possible. When Team indicated that they wanted to improve its energy efficiency and power factor, we knew that we could help. We like to take good care of our industrial customers,” Brown says. 

When high-use utility customers such as factories improve efficiencies, the benefits flow both ways. Kaukauna Utilities generates a certain amount of its power through seven hydroelectric facilities in the Fox River Valley and buys the rest on the spot market. But buying energy on the open market incurs penalties to the utility.

“If our customers can reduce their energy demand, we can reduce the amount of electricity we have to purchase on the market. We save costs and therefore pass on less cost to the end user,” Brown says. “Additionally, reduced demand enables us to generate fewer kilowatt hours to meet that demand. Our ‘avoided cost’ is converted into rebates for customers that use energy efficiently.”

Rebates

With energy efficiency in mind, Team tested the Miller Electric XMT 304 inverter-based power source for a year in-house before selecting it. The XMT is a CC/CV, multiple-process power source with a 5 to 400 amp output (300 amps at 60 percent duty cycle). It features an average energy efficiency of 85 percent and good power factor. Team installed 18 XMT 304s in March and April of 2001 and will eventually purchase up to 52 units. 

Versus Team’s old 250-amp multiple-process power sources, the XMT inverter saves Team Industries $303 per machine per year in electricity costs, an average figure Team and Kaukauna Utilities derived from test meters and other power consumption calculations. In addition, because Team’s power factor improved by using more energy-efficient machines, Kaukauna now returns a $413 rebate per inverter, up to a total rebate of $7,500.

“At our plant, welding machines are among the most common electrical devices – 52 welding units are in use here daily,” notes John Panetti, Team’s executive vice president of manufacturing. “That makes them one of the highest users of electrical power, so we definitely needed the most energy-efficient welding machine we could find to replace our older units.” 

Obviously, Team officials also critically evaluated the XMT 304’s arc characteristics. “Our testing proved that the Miller power sources would be able to deliver a smooth and stable arc consistently and in all welding modes,” Panetti says. “This was key for us, because our work demands high-quality, multi-process welding capabilities.

“We’re very happy to be working with Kaukauna Utilities and Miller Electric on this whole process, rather than someone just trying to sell us any new machine and the utility company just telling us we need to lower our usage,” adds Murphy. “We’re able to work closely with both organizations and find what would work best for them as well as Team. It’s been a big plus working together on this project.”

Maintenance Efficiency

The second major force driving change at Team Industries was rising maintenance costs associated with the company’s aging welding units. “We could have gotten by with our existing machines,” says Jason Sturn, Team’s maintenance supervisor, “but it’s not always the right thing to do. You have to weigh how much downtime and repair bills you’re accumulating using older equipment that starts to break or wear out.”

Consider mode switches. As the welding machines’ mode switches reached their upper tolerance and began to fail, “I went through as many as two or three mode switches per machine per year at a cost of about $186 per switch, Sturn says. “The mode switches for those older machines are supposed to last three to four years.” 

At the beginning of this rash of switch failures, a welding operator was down for two hours during his shift while his faltering machine was pulled off-line and a replacement was readied for him. In addition to the cost of the switch, therefore, was the extra $50/hr. cost of the operator’s downtime. Mode switch failures became more predictable, however, and Team became adept at limiting downtime during shifts. “It’s a learning curve when a particular problem begins happening and soon you become expert at a certain repair,” Sturn says. “But these are things you really don’t want to get good at.”

Unfortunately, Team also had to replace fan motors and PC boards on the older welding units, as a generation of fan motors and boards began to show their age. The price of this aging process was $125 for a new fan motor and $574 for the associated PC board. “We’re not exactly sure what’s causing these components to fail, but age has something to do with it, because five years ago we weren’t burning up PC boards like we are now with the older machines,” Sturn observes. “Plus, there’s no warning when a fan is about to go. It just goes. That’s another two hours of downtime by the time you shut the operator down, get all the covers off, pull the fan, and put the new fan in.”

Same-day fan replacement assumes the part is in stock, which hasn’t always been the case. “They don’t always stock the parts you want, especially for older machines. I discovered it sometimes took two weeks to get a fan motor – that doesn’t do me any good,” he laments. “Now, I have two fan motors in inventory because we’ve lost as many as two in one week.”

Acquired 13 years ago when they were the first multi-process machines on the market, Team’s older generation welding machines provided years of service, but now connections have also begun to deteriorate. “Constant use, heat build-up, and vibration are affecting the connections to switches and tripping thermostats,” says Sturn. “The stress of frequent repairs adds to the problem, so the connection would fail again despite repair work.”

Team’s first 18 inverter units have replaced the older generation machines that had the highest maintenance record and/or those getting the most arc time. The new inverters haven’t been in place long enough to gauge their reliability, but the XMT 304’s design should significantly increase maintenance efficiency. Since its introduction in 1996, this unit set the new standard for inverter reliability. 

Welding Quality

Since 1987, Team Industries has provided piping, tank and modular fabrication for the brewery, chemical, pulp and paper, power, refinery, petrochemical and industrial gas industries, to name a few. In the last 14 years, its manufacturing capabilities have expanded to include pipe spools, skid-mounted equipment modules and manifold assemblies, structural modular framing, rack-mounted process piping, ASME tanks and pressure vessels, and tanks, hoppers and fittings of all varieties. The company also manufacturers its own line of welding positioners and grippers, which it designed especially for pipe fabrication.

Team is authorized to use the ASME “PP” and “U” code symbol stamps and is qualified to perform code fabrication to ASME Section I and VIII Division I, ASME B31.1 and B31.3, as well as other National Code Standards. Team’s 80 welding operators use SMAW, GMAW, GTAW, SAW and FCAW processes. The company works with a wide range of materials, including 304, 316, 321 and duplex stainless, carbon steel, cast alloys, aluminum, nickel base alloys, titanium and P91 and P22 chromes.

“Basically we sell welding, and welding is our forte,” says Panetti. “We have some of the best operators in the world welding here. The systems we build are subject to pressures as high as 2,500 pounds psi at 1,500 degrees Fahrenheit. We x-ray approximately 1,000 pipe welds per month. We can’t afford not to provide the latest technology to our welding operators.”

Use of advanced technology allows Team to claim a rejection rate of less than one-half of one percent for materials that arrive to the field, one of the lowest rates in Team’s industry. Consequently, the company avoids expensive rework. For example, a weld that fails Team’s x-ray or ultrasonic tests can cost $200 to $300 to repair. The loss of the operator’s productivity increases that figure to a $400 to $500 loss.

The new inverter welding power sources have contributed to Team’s quality and manufacturing efforts in a number of ways. User-friendliness was the first benefit Team’s welding operators experienced. “We brought the units in on Friday, their day off, and on Monday morning the welding operators figured out what to do on their own,” Panetti remembers. “If there were any major questions, a 15-minute explanation solved the problem. The XMT’s process selector switch makes switching between processes fast and simple.”

“Speed is what we’re looking for,” adds Tony Fisher, Team’s welding supervisor. “We switch a lot from GTAW to GMAW to FCAW as far as laying the root pass and filler passes. To enable quick process switching, we turn the process selection switch on the XMT’s front panel and then use a Miller Process Selector Control, which we fixed to the top of the inverter.”

"Switching from MIG wire to flux cored wire is a lot easier with these new machines,” says Jeff Robedeaus, Team journeyman welder. “Whatever kind of wire you’re using, you can grab each welding whip and just go. There’s no messing around with a bunch of knobs, and changing lugs and polarity between modes.”

Many Team welding operators seem particularly impressed with the XMT 304’s TIG welding capabilities. “It seems to have a nice, stable, smooth arc with TIG welding; it’s much nicer than the machines we had,” says Chris Starks, welding operator. “I also can get a lot better penetration with it while still maintaining good puddle control.” 

“The way the XMT 304 handles the TIG arc at such low amperage is really sweet,” notes Fisher. “The operators can watch the root and see if they’re starting to lose it, and when they start to back off, it’s very smooth – they have good control. When they get down to the end of a weld and where they like to just tail out, they can back down to practically zero amps.”

In addition, the XMT affords more available amperage to handle Team’s higher workloads. “Our operators had become very efficient with the higher amperages, and we were at the top end of what our older machines could put out,” Panetti notes. “The XMT allows us to use another 100 amps. Plus, it gives us 10 amps of auxiliary power to run our accessories, such as water coolers, wire feeders and high frequency units.” 

More to Come

The second phase of Team’s welding power source replacement project starts next year. From all indications, the transition will continue seamlessly, according to Panetti. “We rely heavily on feedback from the plant floor,” he says. “So far, from everyone the word is ‘smooth.’ The operators are very pleased with the new power sources, whether the application is TIG or MIG. I have yet to hear even a hint of a negative comment about the XMT 304s or our decision to buy them.”

The increased efficiency that the XMT 304 units have given Team’s welding operators has had a ripple effect throughout the plant. “Our pipe fitters are a little concerned that they can’t keep pace with the welders,” he notes. “But I think they’ll rise to the challenge and adapt to this new production level – with the new Miller power sources, the welding operators aren’t going to be working any slower.”

# # #

Efficiency and Power Factor

Inverters provide both good electrical efficiency and good power factor. Before 1995, all transformer-based welding power sources did a poor job of converting incoming line power to welding output power. Efficiencies of 60 to 70 percent were typical, with constant current machines being bigger offenders than constant voltage machines. With inefficient welders, most of the “lost” primary power ends up heating the transformer (which is why welding machines have cooling fans). All that hot air costs a lot of money in the form of high utility bills. In fact, if someone gave you a free machine, but it used power inefficiently, you could be losing money within two years.

In 1995, Miller improved the way the copper wire wraps around the iron transformer core and added a cooling fan that only ran when needed. This boosted power conversion efficiency to approximately 80 percent for Miller’s traditional three-phase input machines and 85 percent for its inverters. An independent laboratory confirmed that the new power sources provided a 10 to nearly 25 percent energy efficiency advantage over units featuring the old transformer design. The calculations in the chart show the impact of energy efficiency on utility bills.

Power Factor Correction

Power factor is defined as the ratio of real power (or “working” power, the power that produces useful work, such as creating a welding arc) to apparent power (the total power being provided by the utility). Simply put, the current required to operate a piece of equipment having low power factor is quite a bit higher than that required for equipment having high power factor. Many utility companies charge an additional fee if an industrial facility has low power factor. 

Low power factor is caused by inductive loads, such as in the transformer of a welding power source. To overcome low power factor, manufacturers like Miller Electric incorporate a feature called power factor correction (PFC) into a welding power source. PFC is optional on some power sources and a standard function on others, including the XMT. As a result of PFC, the XMT 304 draws just 18.9 amps on 460 V, 3-phase primary service to produce a 300 amp/32 VDC welding output. An old CC/CV power source without PFC may draw 30 to more than 40 amps of primary current, or more than double the load of an inverter.

Inverter Power Calculations 

Arc on welding cost: 300 amps x 30 volts (welding output) x $0.11* (energy cost per kW-HR) x 2400 hours (annual arc-on time) ¸ .85 (weld efficiency) = $2,795.29

Unit idle cost: .028 kW idle power draw x $0.11 x 1600 hours idle time = $4.93

Old Welding Unit Calculations 

Arc on welding cost: 300 amps x 30 volts (welding output) x $0.11 (energy cost per kW-HR) x 2400 hours (annual arc-on time) ¸ .71 (weld efficiency) = $3,346.48

Unit idle cost: .411 kW idle power draw x $0.11 x 1600 hours idle time = $72.34

Power cost to operate old machine:                 $3,418.82

Power cost to operate inverter:                       $2,800.22

Power savings potential with inverter                $  618.60 per year, per machine