Lincoln Electric SVM170-A Constant Voltage Output, Theory Of Operation, Section, Master, Return

E-4 THEORY OF OPERATION E-4

TOC	TOC	FIGURE E.4 — CONSTANT VOLTAGE OUTPUT.
Section	Master		GAS	FAN	SPOOL
			SOLENOID	MOTOR	GUN		WIRE
							DRIVE
		WIRE					MOTOR
to	to
		SPEED
Return	Return	ARC	CONTROL
		VOLTAGE	BOARD
		AUX					TACH
		115 VAC						GUN TRIGGER
			RECTIFIER
			DIODE	G				FEEDBACK
			BRIDGE
				A
		30 VAC		T
				E
		LINE	SNUBBER	S
			BOARD
		SWITCH		I
				G
				N
TOC				A
	TOC			L
Section	Master			POWER		C	F	OUTPUT	POSITIVE
		RECONNECT		ENHANCEMENT		A		CHOKE
									TERMINAL
		MAIN		CHOKE		P	E
		TRANSFORMER				A	E
			SCR			C	D
to	to						B
			RECTIFIER			I
						T	A
Return	Return
						O	C		NEGATIVE
						R	K
									TERMINAL
						S
						SHUNT

		CONSTANT VOLTAGE OUTPUT	power factor enhancement choke is filtered by the
			capacitor bank resulting in a constant voltage DC out-
		The controlled DC output from the SCR rectifier	put. Since the output choke is in series with the posi-
			tive leg of the rectifier and also in series with the gun
		assembly is supplied to the power factor enhancement
			and welding load, a filtered constant voltage output is
		choke which limits the rate at which the supply current
Return to Section TOC			applied to the output terminals of the machine.
	Return to Master TOC	rises through the capacitors. The DC output from the

Section TOC	Master TOC
to	to	NOTE: Unshaded areas of Block Logic
		Diagram are the subject of discussion
Return	Return
		POWER MIG 255C