Lincoln Electric SVM129-B service manual Table of Contents Theory of Operation Section

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Section E-1 Section E-1

TABLE OF CONTENTS

-THEORY OF OPERATION SECTION-

Theory of Operation	Section E
General Description	E-2
Input Voltage	E-2
Reconnect, Protection Board, Rectification and Precharge	E-3
Switch Boards	E-4
Main Transformer, Output Rectification and Choke	E-5
Control Board, IGBT Drive and Module	E-6
Power Board	E-7
Remote Protection Board	E-7
Field Effect Transistor (FET) Operation	E-8
Pulse Width Modulation	E-9
Minimum Output	E-9
Maximum Output	E-9
Protective Circuits	E-10
Overload Protection	E-10
Thermal Protection	E-10

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TOC

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
						O	T	O	I	A
						N	E	A	V	R
							C
						N	T	R	E	D
						E	I	D	R
							O
						C	N
	"A"					T
	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		R D	C
		4				FET	D
			V		H
TRANS			A
			C			LESS THAN 1VDC
T4			T
			H					PULSE TRANSFORMER SIGNAL
			E

RPWM SIGNAL

M

O

S15VDC

T

A
T	GUN TRIGGER	CONTROL BOARD

36VAC

TAILOUT	PEAK	BACK-	PEAK	HOT	BACK-	WIRE
	CURRENT	GROUND				SIZE
CONTROL			CURRENT	START	GROUND
(STT II ONLY)	METER	METER	CONTROL CONTROL CONTROL			SWITCH

CURRENT

TRANS

T3

WIRE

TYPE

SWITCH

POSITIVE

OUTPUT

TERMINAL

MAIN

TRANSFORMER1 OHM

T2

	CURRENT	IGBT		NEGATIVE
	SENSOR	MODULE		OUTPUT
				TERMINAL
CHOKE				R
				E
				M
			D	O
				T
			R
			I	E	B
			V
			E	P	O
			S	R	A
			I	O	R
			G	T
			N		D
				E
			A
				C
			L
				T

I

O

N

CURRENT FEEDBACK

IGBT

DRIVER

BOARD

VOLTAGE FEEDBACK

10VAC AND 6VAC

42VAC

VOLTAGE

SENSING

RECEPTACLE

REMOTE

CONTROL

RECEPTACLE

WIRE

FEEDER

RECEPTACLE

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FIGURE E.1 – INVERTEC STT

INVERTEC STT