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TRANSPORTING
The Converter may be carried by one or two persons
using the front and rear top and bottom handles. It can
also be set vertically on a two wheel cart, or horizon-
tally on a wagon, to move it longer distances.
STORAGE
The Multi-Weld 350 may be set on a floor, or shelf, hor-
izontally on its skid, or vertically standing on its rear top
and bottom handles.
PROTECTION FEATURES
The Multi-Weld 350 design features electronic protec-
tion systems to help assure reliable operation even
under adverse conditions. These systems include:
FAN AS NEEDED (F.A.N.)
The cooling fan will turn on when the arc starts and
remain on for about a minute after the arc is out to cool
down the power components.
This feature electronically controls the fan so it does
not run continuously when the power switch is turned
on. This will minimize the amount of contaminate and
clogging debris which may be drawn into the
Converter. It enhances the “Central-Air” system design
which intakes lower velocity air through the higher side
louvers and blows it out through the lower back louvers
with higher velocity.
OVER-VOLTAGE PROTECTION
The Multi-Weld 350 input contactor will open if the input
supply voltage is above 113 VDC, and will automatical-
ly reclose if the voltage drops back below. During Over-
Voltage Shutdown the panel displays will be as appro-
priate for the non-welding mode. (See FRONT PANEL
CONTROLS in this section.)
When the contactor recloses, the output of the
Converter will reactivate. Switching OFF input power
prevents unexpected reactivation.
This feature protects internal components of the
Converter from excessive voltage levels.
OVER-CURRENT PROTECTION
The maximum output current of the Multi-Weld 350 is
electronically limited, to protect internal power compo-
nents, so as not to exceed about 375 amps average
and 500 amps peak. When the current load starts to
exceed these limits, the output is reduced (lower volt-
age) to sustain these maximum levels until the current
is reduced, even to a shorted output.
Prolonged output at this maximum current limit level
may eventually overheat the Converter’s internal
power components, causing over-temperature shut-
down. (See following section.)
Short circuit protection is also provided to reduce max-
imum output current to about 200 amps, if the output
voltage is reduced, by loading or current limiting, to
below 14 volts for over 7 seconds (indicating a shorted
output). The output current must be interrupted to reset
this reduced protective level.
This maximum 200 amp short circuit level will allow
using the Multi-Weld 350 for “pipe-thawing” applica-
tions without causing over-temperature shutdown.
(See following section.)
OVER-TEMPERATURE SHUTDOWN
A second over-load protection switch in the Imbalance
Protector Module was added to Multi-Weld 350 models
with codes 10736 and higher. This module senses for
an imbalance of current between the paralleled
Chopper boards by sensing the differential choke volt-
age. If this voltage exceeds 1 V for a sustained time,
the Imbalance Protector will also activate over-temper-
ature shutdown to protect the higher current Chopper
board from over heating.
When the thermostat resets, the output of the
Converter will reactivate. Switching OFF input power
prevents reactivation but also shuts off the cooling fan,
which prolongs the reset time.
During Over-Temperature Shutdown the panel displays
will be as appropriate for the non-welding mode. (See
FRONT PANEL CONTROLS in this section.) The fan
will remain running and the Thermal Shutdown (yellow)
Light will be lit until reset. Typically, if shutdown occurs
repeatedly below 300 amps output with fan running,
imbalance of the Chopper board current may likely be
the cause.
B-9 B-9
OPERATION
MULTI-WELD 350
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CAUTION
CAUTION