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E-2

THEORY OF OPERATION

E-2

 

 

 

 

 

GENERAL DESCRIPTION

The Invertec V250-S is a 250 amp arc welding power source that utilizes either single or three phase input power to produce a constant current output. The output response of this machine has been optimized for the SMAW and TIG welding processes.

FIGURE E.1 - INPUT VOLTAGE CIRCUITS

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INPUT

INPUTRECTIFIER LINE

SWITCH

"A"

L

E

A

D

FAN

MOTORS

R

E

C

O

N

N

E

C

T

S

W

I

T

C

H

18VAC

POWER BOARD

MAIN

 

TRANSFORMER

 

 

 

 

CR1

 

 

 

RELAY

 

 

 

IGBT

 

 

 

 

 

 

POSITIVE

CAPACITOR

 

 

OUTPUT

 

 

 

TERMINAL

IGBT

 

 

 

IGBT

 

SHUNT

 

 

 

 

 

CURRENT

 

 

 

TRANSFORMER

 

NEGATIVE

 

 

 

CAPACITOR

 

F

OUTPUT

 

 

TERMINAL

 

 

E

F

IGBT

 

E

E

 

 

D

E

 

 

B

D

 

 

A

B

 

 

C

A

O

 

K

C

V

 

 

E

 

THERMOSTATS

K

R

 

 

V

 

 

 

O

 

 

 

L

 

 

 

T

IGBT GATE SIGNALS

THERMAL

A

G

 

 

E

PROTECTION SIGNAL

CONTROL BOARD

LIGHT

 

CR1 RELAY DRIVE SIGNAL

 

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AUXILIARY

TRANSFORMER

REMOTE

RECEPTACLE

OUTPUT STRIKE ARC

 

 

 

LOCAL/

 

MODE

 

REMOTE

CONTROL CONTROL FORCE

SWITCH

CONTROL

 

 

 

SWITCH

 

 

 

 

INPUT LINE VOLTAGE

The single-phase or three-phase input power of 208, 230 or 460 volts AC is connected to the machine, through a line switch located on the front panel.

A reconnect panel and switch allows the user to con- figure the machine for either a low or high input volt- age and also connect the auxiliary transformer for the appropriate input voltage.

The auxiliary transformer develops the appropriate AC voltages to operate the cooling fans and the control board.

NOTE: Unshaded areas of block logic diagrams are the subject of discussion.

INVERTEC V250-S

Page 26
Image 26
Lincoln Electric V250-S service manual General Description, Input Line Voltage