Lincoln Electric SVM188-A service manual Theory of Operation, Input Circuit and Main TRANS- Former

Page 36

E-2

THEORY OF OPERATION

E-2

 

FIGURE E.2 - INPUT AND TRANSFORMER

 

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CONTROL

POWER

TRANSFORMER

SWITCH

115VAC

 

•

Pilot

 

Light

w

 

•

CR2

 

Secondary

Thermostat

Primary

 

Theromstat

1CR Coil

 

 

R

 

E

 

C

 

O

 

N

 

N

 

E

 

C

 

T

CONTACTOR

CR1

 

 

 

 

 

 

 

TERMINAL

 

 

 

 

 

 

 

 

 

STRIP 1

 

 

 

 

 

 

 

 

 

 

OUTPUT

 

FAULT PROTECTION

 

 

 

 

 

CONTROL

 

 

 

 

 

 

SWITCH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OUTPUT

 

32VAC

 

 

 

 

OUTPUT

CONTROL

 

32VAC

 

 

FIRING

CONTROL SIGNAL

 

 

 

 

 

 

 

 

32VAC

 

 

BOARD

 

 

 

 

 

 

 

 

G

S

 

 

 

 

14-pin

115VAC

Fan

A

I

 

 

 

 

T

G

 

 

 

 

Amphenol

Receptacle

Motor

E

N

 

 

 

 

 

 

 

 

 

A

 

 

 

 

 

 

 

 

 

L

 

 

 

 

T

 

115VAC

 

 

 

 

CONTROL

 

 

S

 

 

 

 

 

 

 

R

•

 

 

 

 

BOARD

 

MODE

T

 

 

 

 

 

E

 

 

OUTPUT

 

 

 

 

 

SWITCH

I

I

 

 

 

 

 

 

M

R

 

 

 

 

 

 

 

 

N

P

TERMINAL

 

 

 

 

 

 

AL

2

 

 

 

 

 

 

 

 

 

SWITCH

 

 

 

F

 

 

42VAC

 

115VAC

 

 

 

 

E

 

 

 

 

 

 

 

 

 

E

 

 

MAIN

 

 

 

 

 

 

D

 

 

 

 

 

 

 

 

B

 

 

TRANSFORMER

 

 

 

 

A

 

 

 

 

 

 

 

 

 

C

 

POSITIVE

 

 

 

 

 

 

 

K

 

 

 

 

 

 

 

 

 

TERMINAL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SHUNT

F

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E

 

 

 

 

 

 

 

 

 

E

 

 

 

 

 

 

 

 

LATCHING

D

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RESISTOR

B

 

 

 

 

 

SCR BRIDGE

 

A

 

 

 

 

 

 

C

NEGATIVE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHOKE

 

K

TERMINAL

 

 

 

 

 

 

 

 

GENERAL DESCRIPTION

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The DC-600 is a three-phase, SCR controlled DC power source. It is capable of either constant current or constant voltage output. It is rated at 600 amps, 100% duty cycle with outstanding arc characteristics for multiple welding processes.

INPUT CIRCUIT AND MAIN TRANS- FORMER

The desired three-phase input power is connected to the DC-600 through an input contactor located in the input box at the rear of the machine. Two phases of the input line are also connected to the control transformer. The secondary of the control transformer supplies 115 VAC power to the control board and to the input con- tactor through the fault protection relay.

A reconnect panel allows the user to configure the machine for the desired input voltage. This three- phase AC input is applied to the primary of the main transformer. The transformer changes the high voltage, low current input power to a lower voltage, higher cur- rent output. The finishes or “neutrals” of the main sec- ondary coils are connected together, and the six starts of the secondary windings are connected to the SCR rectifier assembly.

In addition, the main transformer also has five isolated secondary windings. There are three 32 VAC windings, which provide power and “timing” to the firing board. The 115 VAC winding powers the fan motor and pro- vides the user with up to 20 amps of 115 VAC auxiliary power at the receptacle or 14-pin MS type connector. The 42 VAC winding provides 10 amps of power to the 14 pin MS type connector to power a wire feeder.

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

DC-600

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Contents DC-600 ISAFETYi Safety Electric Shock can killFumes and Gases Can be dangerousPowered equipment For ElectricallyPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcElectromagnetic Compatibility EMC Safety Master Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications DC-600Safety Precautions Electric Shock can KillSelect Proper Location Fuse and Wire Sizes Electrical Input ConnectionsGround Connection Reconnect Procedure Connection for Highest Rating Plate VOLTAGE, 50 or 60 HZConnection for 440 Volts 50 or 60 HZ V 60HZ See Machine Rating Plate for Required Input Supply Voltage Output Connections ELECTRODE, Work and #21 LeadConnections Auxiliary Power Control Connections Terminal Strip 1 T.S.1Terminal Strip 2 T.S.2 DC-600 Table of Contents Operation Section Safety Precautions OperationDesign Features Advantages General DescriptionRecommended Processes and Equipment Meanings of Graphical Symbols on Case Front OFF Input PowerWelding Capability Output Control Output Voltage CurrentMeaning of Graphical Symbol for Ground CON- Nection Controls and SettingsAuxiliary Power in MS-RECEPTACLE OVERLOAD, OVERCURRENT, and Fault ProtectionRemote Control of Machine Operation Welding Procedure RecommendationsOperating Steps NA-3 Automatic Wire Feeder RemoteLN-8 or LN-9 SEMI-AUTOMATIC Wire Feeder LN-7 and Other Constant Wire FeedersDC-600 Table of Contents Accessories Section Accessories Wire Feeders and TractorsFactory or Field Installed Options Field Installed OptionsFigure C.2 MULTI-PROCESS Switch Cable Connections Accessories Table of Contents Maintenance Section Maintenance Safety Precautions Electric Shock can KillRoutine and Periodic Maintenance 1TABLE of CONTENTS-THEORY of Operation Section E-1 Theory of Operation Input Circuit and Main TRANS- FormerFiring CIRCUIT, Control CIR- Cuit and Rectification RectificationFiring Board Thermal Protection SCR Operation DC-600 1TABLE of Contents Troubleshooting and Repair F-1 2TROUBLESHOOTING and REPAIRF-2 HOW to USE Troubleshooting GuideTroubleshooting and Repair PC Board Troubleshooting ProceduresControl Feeder. See Protective Devices Check all three phase input Output Control J1,Pin2. See Wiring Diagram Wiring Diagram PC Board Troubleshooting Guide Test DescriptionMaterials Needed PC Board Troubleshooting Guide Control Board Figure F.2 Control Board LEDsDC-600 Internal Trigger Circuit Test Procedure Internal Trigger Circuit TestInternal Trigger Circuit Test 75 76DC-600 Firing Board Test Firing Board Test Control Board Test Control Board Test Figure F.7 Control BoardMain Transformer Voltage Test Main Transformer Voltage Test Figure F.8 Input Contactor and Reconnect PanelFigure F.9 Transformer Secondaries Main Transformer Voltage Test Control Transformer Test Procedure Control Transformer TestInput Contactor Test Input Contactor Test Voltage TestSCR Bridge Test Anode Cathode Remove Insulating Paint SCR Bridge TestActive Test Scope Settings Maximum Output Setting no Load Minimum Output Setting no Load 35TROUBLESHOOTING and REPAIRF-35 2V/Div Volts DC-600 Input Contactor CR1 CLEANING/REPLACEMENT Input Contactor CLEANING/REPLACEMENT Procedure Cleaning ProcedureContactor Replacement Procedure SCR Rectifier Bridge Removal and Replacement Procedure 42TROUBLESHOOTING and REPAIRF-42 Removal and Replacement ProcedureRemoval Procedure SCR Rectifier BridgeReplacement Procedure Insulator Lock Washer Plain Washer Output Snubber LeadDC-600 Main Transformer and Choke Removal and Replacement Removal and Replacement Main Transformer and ChokeRemoval Procedure Weld Input Idle Amps and Watts Maximum Open Circuit VoltagesDC-600 Table of Contents Diagram Section Electrical Diagrams Wiring Diagram 230/460/575 Volt Machines G3506-1 Schematic Complete Machine G3575 Schematic Control PC Board G3408-1 Control PC Board Assembly G3409-1 Schematic Firing PC Board G3741-1
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