Question on AWS D1.1 2010-3.2.4 FCAW and GMAW Power Sources

Date 03-19-2012 09:23

Gents,

Acc. to 3.2.4 in Clause 3, Constant voltage power supplies shall be used when performing prequalified WPSs using FCAW&GMAW processes. But why is there a variable with limitation of ±15% set for this? please see Table3.8 prequalified WPS variable 12)

Thanks.
Allen

By Lawrence (*****)

Date 03-19-2012 10:59

"Constant Votage" is a term that describes a "type" of power supply typically used for GMAW and FCAW

"Constant Current" is a term used to describe another type of power supply typically used for SMAW and GTAW

For a GMAW/FCAW procedure to be prequalified it "Shall" be accomplished with a Constant voltage type of power supply.

The 15% you mention is a range of actual working arc voltage that is occuring during the weld..

Does this help? or Do you need further explaination?

By allenliao (*)

Date 03-19-2012 11:21

Thank you, your explaination helps me a lot. Maybe I should firstly go to the subject of Arc Welding Power Source.

Thanks.

By js55

Date 03-19-2012 13:06

Another way to explain it would be the difference between static voltage and dynamic voltage(not to be found in any AWS literature). The static voltage is the voltage setting on the machine. And this is what the 15% limit is targeting. The dynamic voltage is the variance in voltage as one is welding based upon instantaneous arc length variances. And this is what the contstant voltage requirement is targeting.