Lincoln Electric SVM129-B service manual Power Board, Remote Protection Board

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E-7 E-7

THEORY OF OPERATION

FIGURE E.7 – POWER BOARD AND REMOTE PROTECTION BOARD

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S	FET	B
W		O
I	CAP	A
T
		R
C	FET
H		D

						PRE -
LINE	INPUT					CHARGE
SWITCH	RECTIFIER		R	P		D	B
			E
		CR1		R	B	R
			C	O			O	CURRENT
			O	T	O	I	A TRANS
			N	E	A	V	R	T3
				C
			N	T	R	E	D
			E	I	D	R
				O
			C	N

T

	"A"
	LEAD		CR2						PRE -
									CHARGE
FAN		18	P B	S		B
	TRANS	VAC			FET
	T1		O O	W		O
	115		W A	I	CAP	A
			E R	T		R
	VAC	2		C
		4	R D		FET	D
		V		H
	TRANS	A
		C			LESS THAN 1VDC
	T4	T						PULSE TRANSFORMER SIGNAL
		H
		E
		R	PWM SIGNAL
		M
		O
		S	15VDC
		T
		A
		T	GUN TRIGGER			CONTROL BOARD
		36VAC
			TAILOUT	PEAK		BACK-	PEAK	HOT	BACK-	WIRE	WIRE
			CONTROL	CURRENT GROUND			CURRENT	START	GROUND	SIZE	TYPE
			(STT II ONLY)	METER		METER	CONTROL CONTROL CONTROL			SWITCH	SWITCH

		POSITIVE
		OUTPUT
		TERMINAL
MAIN	1 OHM
TRANSFORMER
T2
CURRENT	IGBT	NEGATIVE
SENSOR	MODULE	OUTPUT
		TERMINAL
CHOKE		R		VOLTAGE
		E		SENSING
				RECEPTACLE
		M
	D	O
		T
	R			REMOTE
	I	E	B
	V			CONTROL
				RECEPTACLE
	E	P	O
	S	R	A
	I	O	R
	G	T
	N		D
		E
	A
	L	C
		T		WIRE
		I		FEEDER
		O		RECEPTACLE
		N

CURRENT FEEDBACK

IGBT

DRIVER

BOARD

VOLTAGE FEEDBACK

10VAC AND 6VAC

42VAC

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POWER BOARD

The power board creates a pulse transformer drive sig- nal, which is derived from the PWM signal received from the control board. See Pulse Width Modulation discussion. This drive signal is applied to the primary winding of the pulse transformer, which is located on the driver board. The pulse transformer secondary windings generate the proper gate pulse for the switch board FETs. See Field Effect Transistor (FET)

Operation.

The power board supplies a 15VDC supply voltage for the control board and also powers the input relays (CR1 and CR2).

REMOTE PROTECTION BOARD

The remote protection board provides noise suppres- sion and by-pass filtering to protect the internal circuit- ry of the STT machine.

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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.

INVERTEC STT