Lincoln Electric IDEALARC DC-1000 Service Manual page 32

E-4
FIGURE E.4 - PROTECTION DEVICES AND CIRCUITS (CONTACTOR HOLD-IN)
PROTECTION DEVICES AND CIRCUITS
(CONTACTOR HOLD-IN)
Two thermostats protect the DC-1000 from excessive
operating temperatures. Excessive operating tempera-
tures may be caused by a lack of cooling air or operat-
ing the machine beyond the duty cycle and output rat-
ing. If excessive operating temperature should occur,
the thermostat(s) will deactivate the input contactor,
turning the machine off. The input contactor will remain
open until the machine cools. The machine can then be
restarted by operating the start push button.
Upon restart, if the fan does not turn or the air intake
louvers are obstructed, then the input power must be
removed and the fan problem or air obstruction be cor-
rected.
The DC-1000 is also protected against high current
overloads. This electronic protection circuit senses an
overload on the power source and opens the input con-
tactor should the overload remain for a predetermined
time. If the overload is great the machine will shut
down immediately. The input contactor will remain
open until the start push button is operated.
THEORY OF OPERATION
The Remote Control circuit is also protected from
"grounds" or voltage intrusions. If the #73, #74, #75,
#76 or #77 leads come in contact with either of the
machineʼs output cables, the DC-1000 will only operate
at a minimum output or the input contactor will open.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
IDEALARC ® DC-1000
E-4