Lincoln Electric INVERTEC 270SX Service Manual page 17

OVERLOAD PROTECTION
®
Invertec 270SX and 400SX are electrically protected
from producing higher than normal output currents. An
electronic protection circuit limits the current to within
the capabilities of the machine.
THERMAL PROTECTION
There is one thermal device located on the inverter
heatsink and one located on output diodes heatsink;
they protect the machine from excessive operating
temperature.
Excessive temperature may be caused by a lack of
cooling air or by operating the machine beyond the
duty cycle and output rating. If excessive operating
temperature should occur, the Thermal LED indicator
on the control board, will turn ON and the thermostat
will prevent output current.
The thermal protection device is self-resetting once the
machine cools sufficiently. If the shut down was
caused by excessive output or duty cycle and the fan
is operating normally, the power switch may be left on
and the reset should occur within about 15 minute
period. If the fan is not turning or the air intake louvers
are obstructed, the input power must be removed and
the fan problem or air obstruction must be corrected.
PROTECTIVE CIRCUITS
Protective circuits are designed into the 270SX and
400SX to sense trouble and shut down the machine
before damage occurs to the machine's internal
components. There are resetable fuses on the remote
board in the event that a remote cable is damaged.
Page17