Lincoln Electric IM589 INVERTEC V250-S - Manual (Page 15)

B-4 OPERATION B-4
PARALLEL OPERATION
The Invertecs are operable in parallel. For best
results, the currents of each machine should be rea-
sonably well shared. As an example, with two
machines set up in parallel for a 300 amp procedure,
each machine should be set to deliver approximately
150 amps, not 200 amps from one and 100 amps
from the other. This will minimize nuisance foldback
conditions. In general, more than two machines in par-
allel will not be effective due to the voltage require-
ments of procedures in that power range.
To set machine outputs, start with output control pots
and arc force pots in identical positions. Adjust out-
puts and arc forces to maintain current sharing while
establishing the proper output current.
OVERLOAD PROTECTION
The machine is electrically protected from producing
high output currents. Should the output current
exceed 290A, an electronic protection circuit will
reduce the current to less than 200A. The machine
will continue to produce this low current until the pro-
tection circuit is reset. Reset occurs when the output
load is removed.
THERMAL PROTECTION
Thermostats protect the machine from excessive
operating temperatures. Excessive temperatures may
be caused by a lack of cooling air or operating the
machine beyond the duty cycle and output rating. If
excessive operating temperature should occur, the
thermostats will prevent output voltage or current.
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 oper-
ating normally, the Power Switch may be left on and
the reset should occur within a 15 minute period. If the
fans are not turning or the air intake louvers were
obstructed, then the power must be switched off for 15
minutes in order to reset. The fan problem or air
obstruction must also be corrected.
INVERTEC V250-S