Tweco 2460 Heavy Duty CC CV Control Wire Feeder - Manual (Page 13)

DESCRIPTION OF EQUIPMENT
General Description
The Model 2460 Heavy Duty CC/CV Wire Feeder
is designed to control the linear movement of 1/8
inch (3.2 mm) diameter (or less) tubular welding
electrode or 3/32 inch diameter (or less) solid weld-
ing electrode. The basic feeder has been designed
for self-shielding welding electrode and does not
have a gas solenoid.
For use of non self-shielding electrode, optional
gas solenoids are available and may be installed in
this portable feeder.
Metal Inert Gas (MIG) welding process joins metal
parts by electric arc which is established between a
filler metal (consumable welding wire) and the work.
The combination of the consumable wire with the
parent metal forms the weld.
This wire feeder may be used with either a con-
stant-voltage or constant-current type welding ma-
chine. A transformer-rectifier, motor-generator, or
engine-driven welding machine may be used.
Current Capacity and Rating
The welding current on this equipment is passed
through the feedhead assembly. Care must be
taken to make sure that the connections between
the feedhead and the power source connecting
cable as well as between the feedhead and gun
cable assembly connector are tight. Loose connec-
tions cause excessive heating and must be avoided.
This feeder uses arc voltage for its power. The
cable connection between the feedhead and the
power source also provide a power connection for
the feeder control. The other power connection is
made through the voltage sensing lead which must
be connected to the work terminal. Care must be
taken to make sure that the power cable connection
is made between the power source and work. If this
connection is not made, and an attempt is made to
strike an arc, serious damage to the feeder will
occur. By taking power from the welding arc, two
modes of operation result. These are termed CC
and CV mode. When a constant voltage power
source is used, the input voltage to the feeder
remains constant and a fixed wire feed speed will
result for a given dial selection on the feeder. If either
the power source voltage setting or the feeder set-
ting are changed, the output speed will change. This
is called CV mode of operation. When a constant
current power source is used, the arc voltage will
vary and as a result, the wire feed speed will vary
for a fixed dial setting on the feeder. This is called
CC mode of operation. When a constant current
power source is used, an increase in arc voltage will
cause an increase in wire feed speed, but an in-
crease in wire feed speed causes a decrease in arc
voltage. This results in a self-regulating system so
that the feeder keeps the arc voltage constant by
varying the wire feed speed as the arc attempts to
fluctuate. A switch on the back of the feeder is
provided to select between CV or CC. This switch
selects proper control stability for the mode being
used. The switch does
not select the mode of
operation. The mode of operation is determined by
the type of power source being used.
The main application for this wire feeder is for CC
application using tubular self-shielding wires. Most
CC types of power sources do not have a remote
contactor control available. This means that the
electrode is always hot once the power source has
been turned on. It also means that the gun switch
on the wire feeder does not control the power
source, but only controls the starting and stopping
of the wire feeder itself. Since the power source
remains turned on, when the gun switch is released,
care must be taken when terminating the arc. When
the gun switch is released, the operator must also
pull the gun away from the arc to make sure that the
arc is extinguished and does not burn back into the
gun tip.
Internal limiting circuitry limits the maximum speed
independent of input voltage. In addition, a slow
run-in circuit is provided which automatically re-
duces the run in wire feed speed when open circuit
voltage from a CC power source is present.
NOTE: Wire feeder input is protected by a
7 Amp slo-blow fuse. An 1/8 Amp fuse
protects the P.C. Board circuitry should a
short develop between the gun switch lead
to electrode lead. A 5 Amp slo-blow in-line
fuse inside the case protects the wire feed
motor.
Feedhead Assembly
The feed roll drive motor is solid-state controlled
on this unit. One of either of two different motors
(see Parts List for numbers of each) are used,
430429-249
DESCRIPTION OF EQUIPMENT
May 22, 1997 Revised 3-1