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Author: Bob Page

Not All CV is Equal

Constant Voltage (CV) is the most common output for wire processes, but both Miller and Lincoln sometimes use the term loosely. The Miller Bobcat volt-amp curve to the right, for example, looks nothing like a traditional CONSTANT VOLTAGE volt-amp curve but more like a CONSTANT CURRENT (for SMAW and GTAW) “Drooper” curve.

That is, large voltage swings for minor amperage changes, as seen to the right, are not characteristic of a constant voltage power source and will not provide a great arc (especially for MIG wire).

The Miller Trailblazer

The Miller Trailblazer, on the other hand, is a True CV machine. Its volt-amp curve, to the right, shows stable or constant voltage even with significant swings in amperage. The Trailblazer is a true CV machine which is the primary reason the arc is so much better for wire processes than that of a Bobcat. Likewise, the Lincoln Ranger 225 and 250 GXT are not true CV machines whereas the Ranger 305 is.

So, not all “CV” is CV. If you plan on running wire on an engine drive and want the best arc, consult a General Air sales associate for your true CV machine options.