Lincoln Electric R3R-300 Theory of Operation, Input Line Voltage Contactor and Main Transformer

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Section TOC

Master TOC

E-2

E-2

THEORY OF OPERATION

FIGURE E.2 – INPUT LINE VOLTAGE, CONTACTOR AND MAIN TRANSFORMER

CONTROL

TRANSFORMER

FAN

MOTOR

 

OPTIONAL

 

 

 

 

 

 

OPTIONAL

 

POCKET

 

 

 

 

 

 

 

AMPTROL

 

 

 

 

 

 

 

POCKET

TRANSFORMER

 

 

 

 

 

 

AMPTROL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PC BOARD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AMPHENOL

OUTPUT

 

 

CONTROL

 

TERMINAL

 

DIAL

STRIP

ARC FORCE

 

CONTROL

SELECTOR

 

SWITCH

 

 

 

REMOTE

 

 

SWITCH

 

FEEDBACK

CONTROL BOARD

NEGATIVE OUTPUT TERMINAL

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POWER

THERMOSTATS SWITCH

R

E

C

O

N

N

E

C

T

INPUT

CONTACTOR

MAIN

TRANSFORMER

G

S

A

I

T

G

E

N

 

A

 

L

 

S

 

SNUBBER

 

BOARD

SCR / DIODE

HYBRID BRIDGE

F

EOUTPUT

E

CHOKE

D

 

B

 

A

 

C

 

K

 

SHUNT

OPTIONAL

POLARITY

SWITCH

POSITIVE OUTPUT TERMINAL

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GENERAL DESCRIPTION

The Idealarc R3R welder is a three-phase transformer rectifier type constant current power source designed for DC manual welding and air carbon arc cutting. Its power system is SCR controlled with solid state elec- tronic circuitry. Minimum to maximum output is obtained with a single potentiometer control.

INPUT LINE VOLTAGE,

CONTACTOR AND MAIN

TRANSFORMER

The desired three-phase input power is connected to the R3R 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 primary of the

control transformer. The secondary of the control transformer supplies 120VAC power, via the power switch and thermostats, to activate the input contac- tor.

A reconnect panel allows the user to configure the machine for the desired input voltage. This AC input voltage is applied to the primary of the main trans- former.

The transformer changes the high voltage, low current input power to a lower voltage, higher current output. The finishes or “neutrals” of the main secondary coils are connected together, and the three starts of the secondary windings are connected to the rectifier bridge assembly. In addition, three 66VAC phase angle windings are housed in the main transformer assembly. These windings provide power and “timing” for the control board. Two of these coils provide 120VAC for the fan motor.

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

IDEALARC R3R

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Contents Idealarc R3R-300, -400 Safety California Proposition 65 WarningsElectric Shock can kill Cylinder may explode if damaged Précautions DE Sûreté Master Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications Idealarc R3R-300Technical Specifications Idealarc R3R-400 Technical Specifications Idealarc R3R-500 Lifting Safety PrecautionsSelect Suitable Location TiltingInput Connections Ground ConnectionInput Supply Connections Input Wire and Fuse Size Figure A.2 Input Power Supply ConnectionsReconnect Procedure Input Supply Connection DiagramOutput Connections STICK, TIG, AIR/CARBON ARC Cutting Return to SectionIdealarc R3R Table of Contents Operation Section Safety Instructions OPERATIONB-2Operating Instructions General Description Design Features and AdvantagesOperation Recommended ProcessesControls and Settings Figure B.1 Case Front ControlsOperation Welding Operation Operating StepsTable of Contents Accessories Section Factory Installed Options AccessoriesOPTIONS/ACCESSORIES Field Installed OptionsTable of Contents Maintenance Section Maintenance Routine and Periodic MaintenanceFigure D.1 General Component Locations Idealarc R3R Table of Contents Theory of Operation Section Theory of Operation Input Line Voltage Contactor and Main TransformerOutput Rectification CONTROL, and Feedback Figure E.3 Output RECTIFICATION, CONTROL, and FeedbackOptional Polarity Switch and Pocket Amptrol Circuits Protective Devices and Circuits SCR Operation Figure E.5 SCR OperationTable of Contents Troubleshooting & Repair Section Troubleshooting & Repair HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures PC Board can be damaged by static electricityTroubleshooting Guide Output ProblemsSCR/Diode Pocket Amptrol Circuit Input Contactor Output Problems Welding Problems Description Materials NeededTest Procedure Input Contactor TestRemoved Test for Contact Continuity Description Figure F.3 DC Coil Input Contactor Connections Removed Control Transformer T2 Voltage Test Control Transformer T2 Voltage Test Figure F.5 Control Transformer and Lead LocationsTroubleshooting & Repair Main Transformer T1 Voltage Test Main Transformer T1 Voltage Test Figure F.8 Main Secondary Lead Test Points Phase Angle Winding Test Table F.1Figure F.9 Control Board G2206 Test Points Static SCR/DIODE Rectifier Bridge Test Static SCR/DIODE Rectifier Bridge Test Static SCR/DIODE Rectifier Bridge Test Figure F.13 Snubber Board M15370 Plug P5 LocationSCR Test Active SCR Test Active SCR Test Active SCR Test Figure F.20 SCR Tester Circuit and SCR ConnectionsPocket Amptrol Circuit Test Pocket Amptrol Circuit Test Figure F.21 T3 Transformer and Leads Pocket AmptrolFigure F.22 Pocket Amptrol Board Plug P6 and P7 Location Figure F.23 Sensing Resistor R4 Maximum Output Setting no Load Scope SettingsNormal Open Circuit Voltage Waveform Typical Output Voltage Waveform Machine Loaded Typical SCR Gate Voltage Waveform CH1Abnormal Output Voltage Waveform ONE Output SCR not FunctioningInput Contactor CR1 CLEANING/REPLACEMENT Input Contactor CR1 CLEANING/REPLACEMENT Cleaning ProcedureContactor Replacement Procedure FAN Motor and Blade Removal and Replacement FAN Motor and Blade Removal and Replacement ProcedureSCR/DIODE Rectifier Assembly Removal and Replacement SCR/DIODE Rectificer Assembly Removal and ReplacementTroubleshooting ReassemblySCR Removal and Replacement SCR Removal and Replacement Special InstructionsProcedure for the 1/2 Inch Wide Spring Figure F.29 1/2 Wide Leaf SpringClamping Procedure For 1/4-28 CAP Screws Clamping Procedure For 1/4-20 CAP ScrewsProcedure for Inch Wide SpringAfter Replacing the SCRs Mounting of Stud Type Diodes to Aluminum Heat Sinks Mounting of Stud Type Diodes to Aluminum Heat SinksMain Transformer Removal and Replacement Main Transformer Removal & Replacement Removal of Lift BailRemoval of Choke and TOP Iron Assembly Figure F.34 Choke RemovalReassembly of Transformer Coils Figure F.35 Epoxy MIX Application AreasFigure F.36 Coil Lead Placement Figure F.38 Secondary Lead Trim and Weld Detail Reassembling the Main Transformer Into the Machine Reassemble the Lift BailOpen Circuit Voltages Retest After Repair R3RInput Idle Amps and Watts Welding Output Load TestWelding Output Terminals 63/69VDC 61/66VDC Welding Output Terminals 64/72VDC 61/69VDC Idealarc R3R Electrical Diagrams Idealarc R3R Electrical Diagrams DIAGRAMSELECTRICALG-4 Idealarc R3R-400, 500-I, 500 & 600-I Wiring Diagram Pocket Amptrol Schematic Snubber Board Schematic & Layout R3R-300 Control PC Board R3R-400 Control PC Board R3R-500 Control PC Board
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