Lincoln Electric SVM123-A service manual Protection Devices, Circuits Contactor HOLD-IN

E-4 THEORY OF OPERATION E-4

Return to Section TOC	Return to Master TOC	FIGURE E.4 - Protection Devices and Circuits (Contactor Hold-In)
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		PROTECTION DEVICES AND
TOC	TOC	CIRCUITS (CONTACTOR HOLD-IN)
		Two thermostats protect the DC-1000 from exces-	The DC-1000 is also protected against high current
Section	Master	sive operating temperatures. Excessive operating
			overloads. This electronic protection circuit senses
		temperatures may be caused by a lack of cooling air
			an overload on the power source and opens the
		or operating the machine beyond the duty cycle and
			input contactor should the overload remain for a
to	to	output rating. If excessive operating temperature
			predetermined time. If the overload is great the
		should occur, the thermostat(s) will deactivate the
Return	Return
			tactor will remain open until the start push button is
		contactor will remain open until the machine cools.
		input contactor, turning the machine off. The input	machine will shut down immediately. The input con-
		The machine can then be restarted by operating the	operated.
		start push button.	The Remote Control circuit is also protected from
		Upon restart, if the fan does not turn or the air intake	“grounds” or voltage intrusions. If the #73, #74, #75,
			#76 or #77 leads come in contact with either of the
		louvers are obstructed, then the input power must
			machine’s output cables, the DC-1000 will only
		be removed and the fan problem or air obstruction
			operate at a minimum output or the input contactor
		be corrected.
			will open.
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		IDEALARC DC-1000