Under job site conditions, a 55-lb. inverter power source provides arc characteristics to weld combinations of stainless steel and mild steel.

Rich Harris, Contributing Editor

During the product test Bob Gardner used the Invertec V275-S power source and 3/32-in. and 1/8-in. diameter E309-15 stainless steel electrodes to weld Type 309 stainless steel.

(Top) A 100 foot cord allows current adjustments for different electrodes at various locations at the work site.(Bottom) Gardner welds mild steel with 1/8-in and 5/32-in dia. E6010 electrodes with a whipping technique.

Tools are important to most craftsmen. A welder wants the best power source that matches the job requirements in order to meet his weld procedures and complete the job in a reasonable time.

Bob Gardner, owner of a fabrication shop and welding instructor, and the author designed the product test to closely match conditions found on job sites.

The Job at Hand
In his shop Gardner had fabricated Type 309 stainless steel rails for an automatic car wash, Ultimate Car Wash, owned by Art Dykeman in Cleveland. The 2 X 5 in. box rails in a 22 X 9.3 ft. rectangle holds the wash wand as it moves around a vehicle. At the job site, his final step required mounting the rails to mild-steel brackets that had been bolted to the walls of the building.

"To made the welds at the job site," says Gardner, " I need a power source and filler metal that allowed me to weld stainless to stainless steel and stainless to mild steel. I would be working off a 12 ft. ladder around the perimeter of the the rail, so I wanted a remote control to save climbing up and down to adjust the machine. And I wanted an electrode that would work on both base metals."

The Job Site
In the car wash building, Gardner had the 600 lb. rails lifted and clamped into positioned for welding. As most car wash buildings, the wash bay is open on both ends.

The electrical panel, with 110 and 208 V three phase receptacles, was in a room at one end of the building, about 30 feet from the 10 x 30 ft. bay where Gardner would install the rail.

The Tools
For the product test, Gardner wanted a single power supply, so he could weld the stainless and mild steel with the same process. Gardner chose the Invertec V275-S from the Lincoln Electric Company. The power source provides continuous total range output current adjustment, selectable welding modes, and local or remote output control for shielded-metal-arc welding (SMAW) and gas-tungsten-arc welding (GTAW).

Adjustable Arc Force and a two-position Hot Start switch give the welder a sensitive level of arc control. The Touch-Start feature helps to establish the DC GTAW arc without high frequency starting. The welder uses the Arc Force control to change the welding characteristics. The Hot Start control adjusts the starting characteristics for SMAW.

The V275-S rates at constant current DC output of 275 A, 31 V, 35 percent duty cycle, with an output range of 5 to 275 A DC, and constant open circuit voltage of 70 V DC using single or three phase input. Other outputs are: 200 A at 28 V during 100 percent duty cycle and 250 A at 30 V during 60 percent duty cycle.

With up to 275 A of output gives welders access to a wide number of SMAW electrode types, diameters, and applications. The amperage range allows E6010 and E7018 electrodes up to ⁷ /32-in. diameter with both whip and drag techniques for a variety of construction and fabrication applications. The unit also handles air carbon arc cutting and gouging with up to ¹ /16-in. diameter carbon electrodes. Operator controls and adjustment — power switch, output control, local/remote switch, mode switch, and hot start — are located on the case front. Even with gloves on, one turn of the output control knob regulates the entire output range of the power source. The welder can adjust it while under load to the change power source output. When using remote control, this function becomes the limit setting. The hot start controls the amount of starting energy in CC SMAW. When on, it provides a striking current at 260% of the set current or 275 A, whichever is larger then reverts to the set current in 0.4 second.

Arc Force functions in CC SMAW modes to adjust the arc force — a soft arc at the minimum setting and more forceful (crisp) arc at the maximum settings. "The welding machine will react to a short-arc length and it adds current to maintain the arc and avoid sticking," explains Gardner.

The power source has overload and thermal protection. The cooling fan operates once 15 A of welding current is drawn and for 7 min. after the output current has stopped flowing. This will reduce the amount of dirt drawn into the power supply.

"The units meets water requirements for use outside, with an IP23S environmental rating, states Gardner. "These can be set up as in 8-pack racks for multiple welders, such as in shipyards or for iron workers. For arc gouging, a single machine can run up to a ³ /32-in. diameter carbon electrode in parallel for more power."

The 54.5 lb. welding machine features an aluminum chassis on a 13.6 x 9 x 20.25 in. footprint, protective boots on switches, and encapsulated PC boards on trays for environmental protection.

Gardner had 100 ft. of welding cable and 100 ft. of remote output control cable to reach the weld locations. The electrode and work cables come with quick disconnect terminals. The hand and foot amptrol connects directly to a 6-pin amphenol on the front of the unit.

Tool Performance
Up on the ladder Garner easily adjusted the arc force as he changed welding rods from stainless steel to steel electrodes. He used ³ /32-in. and ¹ /8-in.E309-15 stainless steel and ¹ /8-in. and ⁵ /32-in. diameter E6010 and 5P+ for the steel.

"The remote with a 100 foot cord allows me to adjust the current for the different electrodes whether I'm up the ladder or across the bay. That saves me a lot of steps," says Gardner. He used the 30 ft. of primary power cord to set the power source on the ground near the bay.

"For the stainless steel I set the Arc Force at minimum for a soft arc with a ¹ /8-in. 309L-VMR Red Baron rod." Of the many electrodes I've tried, I like the Red Baron from Lincoln Electric because it is moisture resistant and the slag brushes off."

"The Invertec V 275," states Gardner, "provides the arc characteristics needed so I can run 6010 type electrodes using a whipping technique and for stainless steel electrodes — all in a 55 lb. package.