B-5
OPERATION
B-5
OVER-TEMPERATURE SHUTDOWN
The Multi-Weld 350 has a temperature sensing ther-
mostat on the input diode heatsink to protect the
power components within the Converter from over-
heating. If this thermostat temperature exceeds
about95°C (203°F) the Converter will electronically
shut off the output,and turn on the Thermal Shutdown
(yellow) Light until the thermostat is cooled to reset.
A second over-load protection switch in the Imbalance
Protector Module is added to Multi-Weld 350 models
with codes 10736, and higher, but may be retrofitted
to original code 10645 models with the parts order
kit.This module senses for an imbalance of current
between the paralleled Chopper boards by sensing
the differential choke voltage. If this voltage exceeds
1V for a sustained time the Imbalance Protector will
also activate over-temperature shut down to protect
the higher current Chopper board from over heating.
Machines with code 11148, or higher, which use the
G4662-[ ] Peripheral PC Board, also include Peak
Input Voltage Protection that also lights the the
Thermal Shutdown (yellow) panel light if the unit out-
put is shutdown (See OVER-VOLTAGE PROTEC-
TION Section.).
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.
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During Over-Temperature Shutdown the panel dis-
plays will be as appropriate for the non-welding mode.
(See FRONT PANEL CONTROLS in this section),
except 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 cur-
rent may likely be the cause.
MULTI-WELD 350
CAUTION
