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Whenever the CC welding mode is selected and
power is turned on, or power is on and the welding
mode is changed from Constant Voltage (CV) to
Constant Current (CC), the VRD circuitry performs a
self test for approximately five seconds. For one sec-
ond the input contactor and the cooling fan will turn
on, then off. With welding inhibited, the studs will be
examined. Both VRD lights will be on to indicate that
the machine is in self test mode.
After passing the self test, only the green light remains
on and the machine is ready to weld. If the test fails,
both lights will remain on and welding remains inhibit-
ed. This could be caused by the stick electrode hold-
er being shorted to work, or if an across the arc wire
feeder, such as the LN 25, is connected to the power
source.
To use an across the arc feeder in CC mode on a
VRD model, disconnect the feeder’s work sense lead
prior to the self test. After passing the self test, recon-
nect the work sense lead.
• In CC mode, the VRD will reduce the output voltage
regardless of the position of the L'% !&
"!% "'M Switch.
• The voltmeter will display zero volts until the elec-
trode contacts the work and establishes the welding
arc.
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Under normal circumstances, the machine will never
be able to exceed 49 volts while not welding. If,
under abnormal circumstances, the output voltage
were to exceed 49 volts while not welding, the VRD
turns the output off. The green light would be on
because the voltage would be zero and the pilot light
will be off, but establishing an arc would not be pos-
sible. The machine’s L#"*%"!"M Switch
must be cycled off, then back on, to restore normal
operation.
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This welder has thermostatic protection from exces-
sive duty cycles, overloads, loss of cooling, and high
ambient temperatures. When the welder is subjected
to an overload or loss of cooling, a thermostat will
open. The input contactor will open and remain open
until the machine cools; the white POWER light stays
illuminated. No welding is possible during this cool
down period. The machine will reset automatically
when the thermostat cools.
The power source is also protected against overcur-
rents in the SCR bridge assembly through an elec-
tronic protection circuit. This circuit senses currents
over 780 amps on the power source and opens the
input contactor should the overcurrent remain for a
predetermined time (the white POWER light also turns
off).
The predetermined time varies with the amount of
overcurrent; the greater the overcurrent, the shorter
the time. The input contactor will remain open until
the power source is manually started by resetting the
POWER ON/OFF toggle switch.
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The power source is protected against overvoltage
when not welding in CC mode. If the protection circuit
senses voltage in excess of 49V at the studs when no
welding is taking place, the POWER light will turn off.
The input contactor will open up and remain open until
the power source is manually restarted by toggling the
ON/OFF switch.
The power source circuitry is protected from faults on
leads 75, 76, or 77. If any of these leads are connect-
ed to either the positive or negative output leads, the
IDEALARC® DC-600 VRD will either shut down com-
pletely (input contactor opens and white POWER light
turns off), or will operate at minimum output thus pre-
venting any damage to the IDEALARC® DC-600
VRD. If IDEALARC® DC-600 VRD shuts down, it
must be manually started by resetting the POWER
ON/OFF toggle switch.
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The VRD electronic circuitry is designed to reduce the
OCV of the power source in the Constant Current
(CC) Stick welding mode only. The operation of the
machine with the VRD is slightly different than the
operation of a standard machine. The following
describes the machine operation with the VRD
installed in the DC600.
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RED
ON
ON
OFF
OFF
GREEN
ON
OFF
ON
OFF
Power source is in self test mode.
Output voltage is greater than 30 V.
Output voltage is less than 30 V.
Power source is in CV mode.
LED STATUS
LED STATUS