Theory of operation, Thermal protection, Protective circuits – Lincoln Electric INVERTEC POWER WAVE 450 SVM112-B User Manual
Page 58
THERMAL PROTECTION
Two normally closed (NC) thermostats protect the
machine from excessive operating temperatures.
These thermostats are wired in series and are con-
nected to the Control Board. One of the thermostats
is located on the heat sink of a switch board, and the
other is located on the main choke. Excessive tem-
peratures may be caused by a lack of cooling air or
operating the machine beyond the duty cycle or out-
put rating. If excessive operating temperatures should
occur, the thermostats will prevent output from the
machine. The displays will remain on during this time;
and the yellow Thermal light, located of the front of the
machine, will be illuminated. The thermostats are self-
resetting once the machine cools sufficiently. If the
thermostat shutdown was caused by excessive output
or duty cycle and the fans are operating normally, the
Power Switch (SW1) may be left on and the reset
should occur within a 15-minute period. If one or both
of the fans are not turning or the air intake louvers are
obstructed, then the power must be removed from the
machine, and the fan problem air obstruction must be
corrected.
PROTECTIVE CIRCUITS
Protective circuits are designed into the Power Wave
to sense trouble and shut down the machine before
damage occurs to the machine’s internal components.
OVER CURRENT PROTECTION
If the average current exceeds 520 amps, then the
peak current will be limited to 100 amps until the aver-
age current decreases to under 50 amps.
OVER VOLTAGE PROTECTION
A protective circuit is included on the Protection Board
to monitor the voltage across the input capacitors. In
the event that a capacitor voltage is too high, the pro-
tection circuit will prevent output. Also, in the event
that a capacitor voltage is too low, the machine output
is disabled and the “soft start” mode is repeated. The
protection circuit may prevent output if any of the fol-
lowing circumstances occur:
1. Capacitor condition is required. (Required if
machine has been off for a long period of time and
is connected for high input voltage operation.)
2. Voltage across a capacitor exceeds 370 volts.
(High line surges or improper input voltage connec-
tions.)
3. Voltage across a capacitor is under 170 volts. (Due
to improper input voltage connections.)
4. Internal component damage.
THEORY OF OPERATION
E-10
E-10
POWER WAVE 450