8 1.
Relationship of Welding Voltage to Distance between Welding Wire and Workpiece
The welding voltage is proportional to the length of the
current path between the welding wire and workpiece:
a) If the distance between wire and workpiece
increases, the welding voltage will increase. b) If
the distance between the wire and workpiece decreases, the welding voltage will
decrease. c) If the distance
between wire and workpiece remains constant, the welding voltage will remain
constant. 2. Rate
of Wire Melt-Off vs. Rate of Wire Feed a) Constant
Current Power If, for any short period
of time, the current flowing through the welding zone melts off the wire at a
faster rate than it is being fed, the distance
between wire and work will increase, and welding voltage will increase.
Conversely, if for any short period of time, wire is
fed faster than it melts off, the distance between wire and
work will decrease, and welding voltage will decrease. A
constant welding voltage can be maintained if a control unit is used which will
automatically vary the rate of wire feed
with change in welding voltage. b) Constant
Potential Power With a constant potential
power system the arc voltage is maintained by the power supply. Arc current is
controlled by the wire feed speed with increased wire
feed producing increased current. Therefore,
the wire feed system is simplified to a constant speed device and arc control
is performed by the power source.
