Lincoln Electric SVM162-B service manual Figure E.7 AC Welding Output

Models: SVM162-B

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REMOTE
RECEPTACLE
electrically across the negative and positive SCR bridge connections. With the ability of the choke to store energy and the SCRs to turn on at the appropri- ate times, an AC square wave is developed and applied to the output terminals. The bypass board pro- tects the internal circuitry from interference.
ADVANCED CONTROL PANEL RECEPTACLE

TOC TOC

E-6

THEORY OF OPERATION

E-6

FIGURE E.7 – AC WELDING OUTPUT

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FROM

CONTROL

BOARD

OPTIONAL POWER

CORRECTIONFACTOR

CAPACITORS

POWER

SWITCH

PANEL

RECONNECT

BACKGROUND

CIRCUIT

63.5 VAC

 

 

 

REAR GANG

 

WORK

 

 

POLARITY

 

 

 

 

 

 

 

 

 

SWITCH

BYPASS

BOARD

 

 

 

 

FRONT

 

 

 

 

 

 

 

 

 

HIGH FREQUENCY

ELECTRODE

X1

 

 

 

 

 

 

 

TRANSFORMER

REAR

78 VAC

 

 

CHOKE

 

ELECTRODE

AC

DC

 

 

X2

 

 

 

SCR

 

 

HIGH VOLTAGE

 

 

 

 

TRANSFORMER

 

 

BRIDGE

 

 

 

 

AC

DC

SHUNT

 

 

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115 VAC THERMOSTAT

115 VAC VAC115

20 VAC

20 VAC

LEADSGATE

FEEDBACK

GAS

VAC

FAN

 

SOLENOID

 

 

115

CONTROL BOARD

115 VAC

THERMOSTAT

LED's

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MINIMUM

 

 

 

 

 

 

OUTPUT

PROTECTION

METER

STICK

 

 

 

CONTROL

 

 

 

 

BOARD

 

TIG

 

 

 

 

 

 

SWITCH

BALANCE

POST

LOCAL/REMOTE

 

 

 

 

CONTROL

FLOW

SWITCH

MAXIMUM

OUTPUT

CONTROL

AC WELDING OUTPUT

Rotating the polarity switch to the AC position changes the welding power circuit. One lead (X1) of the main transformer secondary is connected to the machineʼs output work terminal. The other secondary lead (X2) is connected to one of the AC connections of the SCR bridge. The electrode terminal is connected to the other AC side of the bridge. The choke is now

FIGURE E.8 DC WELDING CURRENT GENERATION

G

CHOKE

G

ELECTRODE

 

 

 

 

 

G

 

 

G

 

 

 

Section TOC Master TOC

PRIMARY 10

DC

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WORK

PRECISION TIG 275

Page 44
Image 44
Lincoln Electric SVM162-B service manual Figure E.7 AC Welding Output