Tweco VAF4 Transmig - Manual (Page 63)

TRANSMIG VAF4
Manual 0-5231 3-45 INSTALLATION, OPERATION AND SETUP
3.29 PTC Protection of Power Source Contactor Control Output
The Power Source Contactor control circuit on the TRANSMIG VAF4 provides a relay closure to the power source
through pins A and B of the 19 pin control cable. This allows the welding wire to become electrically ‘HOT’ when
the gun switch trigger on the welding gun is pulled. If this relay closure is NOT provided for any reason, the welding
wire WILL NOT be electrically ‘HOT’. The wire will feed, but there will be NO arc when the wire touches the work.
The Transmig VAF4 has a thermal, self reset protection device in the A-B contactor circuit to protect the circuitry
against a fault or overload condition. This protection device will only allow a maximum steady state current in the
range of 180 to 450 milliamps (dependent on ambient temperature) to flow through pins A and B of the 19 pin
control cable to the A-B contactor circuit on the Transmig VAF4.
If this acceptable current range is exceeded for any reason, the self-reset protection circuit located on the motor
control PCB will be activated effectively disabling the A-B contactor circuit. Once the fault or overload condition
has been corrected and the current has returned to an acceptable level, the protection device will automatically
reset and normal operation can resume.
NOTE
The protection circuit will remain activated (there will be NO arc when the wire touches the work) as
long as the acceptable current range is exceeded.
3.30 Ground Fault Operation
The Transmig VAF4 has been equipped with a ground fault protection circuit. This protection circuit is activated
whenever excessive current flow in the protective earth ground is detected. If the ground fault protection circuit
is activated, the yellow FAULT indicator on the front of the feeder will flash at a rate of approximately 0.5 second
on, 0.5 second off. When a ground fault occurs, the feeder will immediately shut down the feeder, gas valve, and
power source contactor. Once the ground fault protection circuit has been set, the wire feeder will not respond to
a gun switch closure until the power is reset by turning the feeder off and back on.
NOTE
Before resetting power to the wire feeder after a ground fault occurrence, determine what caused the
ground fault and correct the problem before attempting to weld again.
3.31 Electronic Motor Protection
The Transmig VAF4 utilizes an electronic protection circuit to protect the motor against overcurrent caused by ex-
cessive load on the motor. This protection will normally trip if the motor stays in current limit for about 10 seconds
and during this 10 second period the fault light will flash at a rate of approximately 0.3 second on, 0.3 second off.
Once this 10 second timing period completes, the protection circuit will trip which will cause the FAULT indicator
LED to light continuously, error code ERR 03 or ERR 04 (refer to Subsection 4.05 Error Code and Remedies) will
be displayed and the wirefeeder will shutdown. In order to reset this condition, the power to the wirefeeder must
be turned OFF then ON to reset and clear Error Code from display.
NOTE
Should this condition occur, check the wire feeding path, and make sure that there is not any restric-
tions or binding on the wire, and that the feedrolls aren’t locked by some obstruction.