Table 7-1.Cable Size Selection Guide
polarity current. By flicking a switch, the welder can
select the current that best suits the job. Figure 7-3 shows
an example of a combination ac/dc rectifier.
Welding cables carry the current to and from the
workpiece. One of the cables runs from the welding
machine to the electrode holder and the other cable
connects the workpiece to the welding machine. The
cable that connects the workpiece to the welding ma-
chine is called the ground. When the machine is turned
on and the operator touches the electrode to the work-
piece, the circuit is completed, current begins to flow,
and the welding process commences.
The welding cables must be flexible, durable, well
insulated, and large enough to carry the required current.
Only cable that is specifically designed for welding
should be used. A highly flexible cable must be used for
the electrode holder connection. This is necessary so the
operator can easily maneuver the electrode holder dur-
ing the welding process. The ground cable need not be
Figure 7-3.Combination ac, dc transformer-rectifier arc welder.
so flexible because once it is connected, it does not
Two factors determine the size of welding cable to
RECTIFIER WELDING MACHINES. Recti-
use: the amperage rating of the machine and the distance
fier welders are single-phase or three-phase transform-
between the work and the machine. If either amperage
ers that have selenium or silicon rectifiers added to
or distance increases, the cable size also must increase.
rectify (change) the output current from alternating to
(See table 7-1.) A cable that is too small for the amperage
direct current. Most of these machines have the capabil-
or the distance between the machine and the work will
ity of producing either ac or dc straight or reverse
overheat. On the other hand, larger size cables are more