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Rural Fabrication Shop Tames Primary Power Fluctuations With New Welding/Cutting Technology from Miller Electric

Southern Ontario is best known as the heart of Canada's manufacturing industry, but a few kilometers off the main highways, it becomes rural farmland. In fact, the 100-acre property that Thompson Welding calls home actually was, up until two years ago, a beef ranch run by Murray Thompson. His son Doug, at the time, had a variety of fabrication jobs out of high school but was looking to settle down permanently into a steady metalworking career. Inspiration hit the Thompson's via indifference to their current jobs and a realization that they could take advantage of a niche marketplace: rural metal fabrication experts.

Who could understand the metal fabrication needs of rural Ontario better than two former farmers with steady welding hands? Add a son who can design and build metal structures simply by looking at a picture, and Thompson Welding was born.

Doug Thompson of Thompson Welding stands by his work: notice the plate welded to the bottom of the snow thrower. He used an XMT 350 CC/CV inverter, 70 Series wire feeder and a Big Window Elite auto-darkening helmet.

However, running their welding equipment at higher amperages exposed a problem common in rural areas, especially those dependent on hydro-electric power (or "hydro" as the locals call it): limited primary power and power fluctuations.

Fortunately, welding technology has come a long way in recent years, and new products allow fabrication shops and farmers/ranchers to weld regardless of the primary power on site. Two machines in particular(Miller Electric Mfg. Co.'s XMT" 350 CC/CV inverter with Auto-Line™ technology and the Spectrum" 625 plasma cutter

with Power Factor Correction (PFC) and LVC™ line voltage compensation(are enabling the Thompson's to grow their business impressively, even with the power limitations of rural Ontario.

Thompson Welding Fabricates More Efficiently with Primary Power Management

"We have 60-amp service here," says Doug Thompson. "If Mom turns the washing machine on or Dad hits the chop saw, the lights will dim. The hydro fluctuations sometimes cause the same problems."

Regardless of shop size, this is the textbook example of where older welding and cutting equipment runs into problems. If the voltage varies by more than 10 percent, older machines cannot compensate for the variations. Voltage variations (spikes, dips or "brownouts") result from the power company, as well as from any heavy load suddenly placed on the primary line, such as a motor starting. Weld imperfections, insufficient penetration and aesthetically poor welds may result. In additional, older, conventional technology machines tend to draw more amperage, which means that fewer pieces of equipment can "share" the available power.

"In our shop, we were looking at installing a couple-hundred amp service because we wanted to add more powerful welders. That service costs a substantial amount of money, especially for three-phase," says Doug. He estimates that those upgrades could have cost his company as much as $5,000 (Canadian).

Thompson wanted to upgrade because business was expanding. "We started out the business with a Millermatic® 210, and that's been a really good machine," says Doug. "But we started getting into 1/2 in. and thicker material for repair heavy equipment and needed to add a bigger welder. We could perform multiple passes on the thicker material using the existing machine, but it's more efficient if you can weld parts with one pass and still have good penetration."

Doug Thompson welds a new 1/2-in. steel plate on to the bottom of this snow throwerwithout blowing a fuse thanks to the low amperage draw of his XMT 350 CC/CV inverter.

Even with the Millermatic 210, Thompson Welding was blowing fuses in the shop. Doug and Murray knew they needed a machine that could weld at a higher output, but also knew they couldn't effectively draw more primary power. The solution came in the form of a visit from the local Praxair representative who provided a machine demonstration.

Doug Thompson says, "The Praxair representative came by with a welder that had Auto-Line. It was a more powerful machine than we thought we were going to need, but the distributor convinced us to test it. That job alone sold us on it, because as I was Stick welding, Dad was running a 15-amp cut-off saw and someone else was running a 15-amp grinder, and it never once fluctuated in the welding."

The XMT 350 with Auto-Line is the most energy efficient inverter in its class. On single-phase, 230V power, it draws 54.6 amps of primary power when welding at a rated output of 300 amps/32 volts at 60 percent duty cycle (Doug was welding at far less than its rated output, so the welder required less primary power). On 460V/three-phase primary power, the XMT 350 draws a mere 17.8 amps when welding at a rated output of 350 amps/34 volts at 60 percent duty cycle.

Miller Electric's exclusive Auto-Line technology creates a near-perfect power factor, which means that it converts nearly all of the primary power into weld power. Hence, it draws less amperage to weld at a given output.

Auto-Line uses what's known as a boost converter to boost primary input power (the XMT 350 can use any power ranging from 190 to 630 V, single- or three-phase, 50 or 60 Hz) to a higher voltage that charges a capacitor. This capacitor stores and discharges the energy, which then goes on to power the inverter. This ensures a constant source of weld power as long as the primary power stays within the 190 to 630 V range. Instead of the ± 15 percent voltage range common on other inverters, the XMT 350 has a +37/-59 percent range when connected to 460 V power and a +274/-17 percent range on 230 V primary.

"The Miller machine with Auto-Line enabled us to weld thicker material and not have to worry about what happens to the arc when the power dips," says Doug.

Having the Right Tools the Key to Success

The XMT 350 is capable of stick, TIG, pulsed TIG, MIG, pulsed MIG, and flux cored welding processes, as well as air carbon arc cutting and gouging. It also has an excellent low-end MIG arc for short circuit welding thin material, especially stainless steel. Thompson Welding uses the full range of the XMT 350's welding capabilities in its day-to-day work. The company sells and rents bleachers of its own design (see photo) for events in southern Ontario such as festivals and fairs and builds each unit from scratch. The bleachers are MIG welded, with the majority of the welding on these structures consisting of .125-wall steel tubing and angle iron.

Father and son team Murry (left) and Doug Thompson designed and fabricated this portable bleacher using Miller welding and plasma cutting equipment.

For field welding, such as welding stables in area barns, Thompson Welding has relied on the machine's Stick capabilities. They also encounter plenty of opportunities to TIG weld, such as aluminum boxes for pesticide sprayers used in local apple orchards. For those applications, Thompson Welding uses a Syncrowave" 180 SD AC/DC TIG/Stick welder in the shop or a Trailblazer" 301G engine-driven welding generator with multiple process capabilities (Stick, MIG, flux cored and AC/DC TIG).

Being a full-service metal fabrication shop, Thompson Welding also cuts and forms much of the materials they put into their products. For this, the company relies on the Spectrum 625 plasma cutter. Plasma cutting eliminates the possibility of running out of gas (it uses compressed air for "fuel") and cuts quickly, accurately and cleanly, making it more effective than cutting with an oxy-fuel torch for fabrication purposes.

Machines like this, with a 40-amp output, can cut 1/2-thick mild steel at a rate of 10 inches per minute (IPM) using a hand-held torch. Productivity increases on thinner metals, slicing through 1/4-in. steel at a rate of more than 60 IPM and 1/8-in. steel at 200 IPM.

Originally purchased to cut through aluminum, Thompson Welding uses the plasma cutter for a variety of applications, such as manufacturing and repairing large snow throwers. As with welding machines, primary power quality and availability can be an issue. To combat this, the Spectrum 625 features Power Factor Correction (PFC). It draws about 30 amps on a 230 V line, or about 30 percent less than the competition. It also features LVC' line voltage compensation, which enables the unit to maintain a steady output as long as the primary voltage remains within a 175 to 264 V range. A steady output ensure a clean cut, reducing or eliminating the need for post-cutting polishing or grinding.

"A plasma cutter is the only way to cut aluminum," says Murry Thompson. When working on jobs together, Murry does the cutting and Doug does the welding. "And on the snow blower blades, I can show you where we cut with a cutting torch and where we cut with a plasma cutter, and the straightness of the cut with the plasma cutter is clearly better."

Today's generation of plasma cutters are also extremely lightweight and portable. This allows the Thompsons to transport it with ease from jobsite to jobsite via their work trailer. Some, but not all, plasma cutters are designed specifically to operate off of engine drives like Thompson's Trailblazer. Combined with a Miller Spoolmatic" spoolgun for MIG welding aluminum, the Thompson's simply throw the plasma cutter on the trailer, plug it into the engine drive, and they have a fully portable welding shop(a perfect set-up for remote fabrication and repair work.

The equipment that Doug and Murray Thompson operate each day needs to be of a quality that is consistent and produces strong welds and smooth cuts. That can be a challenge when working with the limitations of primary power in their rural base of operations. But with advances in welding and cutting technologies like Auto-Line, PFC and LVC line voltage compensation, Thompson Welding knows there is no task they can't tackle.

"When going into business, you really have to be able to do everything," says Doug Thompson. "With this equipment, we've been able to work with the materials we need to and do so within the limitations of our rural power."

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