Saving Money and Power With New Inverter Technology
September 2, 2002
If you want to boost manufacturing efficiency, don't overlook one obvious place for improvement: replacing welding machines that are more than five years old. Believe it or not, you might make more money by throwing those vintage machines in the scrap hopper than continuing to weld with them. That's because old Stick and DC TIG units raise utility bills, create poor power factor, take up too much space, require parts and labor to keep running and may not maintain a consistent weld output.
Conversely, state-of-the-art welding machines operate so efficiently that they easily create payback within the five to seven years industry standard. Even better, they produce high-quality weld beads, provide multiple process capabilities and operators enjoy welding with them more. This story is the first in a three-part series that focuses on how investing in advanced welding technology makes good business sense.
Machines with older technology typically make very poor use of the incoming line power, wasting up to 40% or more of it as heat. New generation solid state machines like Miller's Dimension™ 452 use power very efficiently, and inverters like Miller's XMT® 304 are even better. They operate at an average efficiency of 85%, which reduces utility bills.
The five-step process shown below explains how to calculate operating costs. The example is for welding at 300 A/30 V with the XMT and its 85% efficiency and .028 kW idle draw. Plugging in the numbers for a once-popular CC/CV machine (but now outdated with its 71% efficiency and .441kW idle draw) proves that the XMT reduces power use by 5,624 kW-Hrs. If you pay $0.11 per kW-Hr (an industry average according to the March 2001 Energy Users News), the XMT saves you $618.64 each year. With a list price of $3,218, this means the XMT pays for itself in about five years . . . if you used power savings alone
Watch for the next issue of Applied Welding to see how you can cut payback time to 25 months.
Calculating Operating Costs
1. (300 Output Amps x 30 Output Volts) 1000 = 9 kW Output Power
2. 9 kW % Efficiency = 10.588 kW Input Power
3. 10.588 x 2,400 Hrs arc-on time = 25,411.2 kW-Hrs welding
4. .028 kW draw at idle x 1600 Hrs idle time = 44.8 kW-Hrs idling
5. 25,456 kW-Hrs total x $0.11 per kW-Hr = $2,800.16 Operating Cost/Year