Lincoln Electric SVM129-B service manual Theory of Operation, General Description, Input Voltage

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E-2 E-2

THEORY OF OPERATION

FIGURE E.2 – INPUT VOLTAGE

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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

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 -

FAN

18

S

B

CHARGE

P B

TRANS

VAC

FET

T1

O O

W

O

W A

I

CAP

A

115

E R

T

R

VAC

2

C

4

R D

FET

V

H

D

TRANS

A

C

LESS THAN 1VDC

T4

T

PULSE TRANSFORMER SIGNAL

H

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	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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GENERAL DESCRIPTION

The Invertec STT is a 225 ampere, inverter based, arc welding power supply specifically designed for the Surface Tension Transfer (STT) welding process. It cannot be classified as either a constant current (CC) or a constant voltage (CV) machine. The STT pro- duces current of a desired waveform to reduce spatter and fumes. The STT process is optimized for short - circuit GMAW welding only.

INPUT VOLTAGE

The Invertec STT can be connected for a variety of three-phase voltages. The initial input power is applied to the STT through a line switch located on the front of the machine. The AC input voltage is applied to the input rectifier and the T1 auxiliary transformer. The T1 transformer develops the appropriate AC voltages to operate the cooling fan, the power and control boards. The T1 transformer also supplies primary voltage to the T4 auxiliary transformer as well as 42 VAC to an exter- nal wire feeder. The T4 transformer supplies power to the IGBT drive board and the control board.

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

INVERTEC STT