Tweco VA 4000S Ultra-Feed - Manual (Page 36)

ULTRAFEED VA 4000S
OPERATION 4-10 Manual No. 0-5135
4.10 PTC Protection of A-B Circuit
The A-B contactor circuit on the Ultrafeed VA 4000 S
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 Ultrafeed VA 4000 S 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 Ultrafeed VA 4000 S.
If this acceptable current range is exceeded for any reason,
the self-reset protection circuit located on the motor
control board 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.
4.11 Ground Fault Operation
The Ultrafeed VA 4000 S 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 1 second
on, 1 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.
4.12 Electronic Motor Protection
The Ultrafeed VA 4000 S utilizes an electronic protection
circuit to protect the motor against overcurrent caused
by excessive load on the motor. This protection will
normally trip if the motor stays in current limit for about
10 seconds. Should this occur, the protection circuit will
trip which will cause the FAULT indicator LED to light
continuously. In order to reset this condition, cycle power
on the unit.
NOTE
Should this condition occur, check the wire
feeding path including the feed rolls. Make sure
there are no restrictions or binding of the wire
or rolls.
4.13 Software Features
The Ultrafeed VA 4000 S is designed to be upgraded with
various options. One of the options (Advanced Interface
Kit) allows many features (including timer times, and wire
speed limits) to be programmed via one of the serial ports
on the feeder through the optional Graphical User Software
(GUS) package.
If some of the features on the feeder aren’t working
correctly, they may have been set to a different value with
GUS. To reset the machine to its default state, turn the
unit on while holding the gun trigger, and holding the
PURGE and INCH buttons in. After about 10 seconds,
the unit should be reset to factory defaults.
NOTE
Take wire feed tension off so that the wire will
not feed.
4.14 Arc Signal Overide
Switch #5 on the motor control board configures the wire
feeder for the presence of Arc Established signals from a
power source. If the power source has either an Arc
Established (as most Thermal Arc power sources have),
or a Current Feedback signal has (as most competitive
power sources have), then this switch should be CLOSED.
If the power source does not have these ‘Arc Signals’,
then this switch should be OPEN. This switch allows the
2 Step / 4 Step and timer features to work, although they
will not be timed from the true start of the arc, but instead
from when the gun trigger is pulled.