Thermal Protection | Lincoln Electric SVM 117-A manual

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E-5	THEORY OF OPERATION	E-5
	THEORY OF OPERATION

THERMAL PROTECTION

THERMAL PROTECTION

A thermostat protects the machine from excessive operating temperatures. Excessive operating temper- atures may be caused by a lack of cooling air or oper- ating the machine beyond the duty cycle and output rating. There are three thermostats within the WIRE- MATIC 250 machine. One of the thermostats, located on the output choke, energizes the cooling fan motors when required. The other choke thermostat "opens" the trigger circuit, preventing machine weld output and wire feed, if excessive operating temperatures are detected. The third thermostat insures that the fan motors are operating when required.

The thermostats are self-resetting once the machine cools sufficiently. If the thermostat shutdown is caused by excessive output or duty cycle and the fans are operating normally, the power switch may be left on and the reset should occur within a 15 minute period. If the fans are not turning or the air intake louvers are obstructed, then the input power must be removed and the fan problem or air obstruction be corrected.

NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion

WIRE-MATIC 250

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Lincoln Electric SVM 117-A service manual Thermal Protection

Contents

WIRE-MATIC Safety Depends on You Safety ARC Welding can be hazardous Cylinder may explode if damaged Electric and MAG- Netic Fields Iii Précautions DE Sûreté Sûreté Pour Soudage a L’Arc WIRE-MATIC Table of Contents Table of Contents Installation Fuse Superlag Duty Cycle Amps Volts at Rated AmpsCurrent Range Type 750C Copper Input Connections Safety PrecautionsSelect Proper Location Stacking Fuse and Wire Sizes Input Power Connections and Ground Connections Connect Shielding GAS Reconnect Procedure Figure A.4 Input Air Supply Connections Figure A.5 Reconnect Diagram For 208/230/1/60 Machines Connect Output Components GUN Liner and Contact InstallationInstall the Work Clamp Output Polarity Connection Wire Size Conversion Parts GUN and Cable Installation WIRE-MATIC Operation WELDING, Cutting Safety InstructionsGeneral Description Power Source Features Design Features AdvantagesUnit Features Recommended Processes and Equipment Limitations Wire Feeder FeaturesMachine Capability Duty Cycle Amps Volts Controls and Settings Figure B.1 Operator Controls Loading the Wire Reel Using the Wire Drive RollProcedure for Changing Drive Roll To mount 10 to 30 lb. spools 8 and 12 diameter Proper Wire FeedingFeeding Electrode Starting the Welder Setting Idle Roll PressureOperating Steps Making a Weld WIRE-MATIC Accessories K607-1 Spool GUN Adapter KIT OPTIONS/ACCESSORIESInstalling the K607-1 Spool GUN Adapter KIT Installation Spool GUN Module Board Spool GUN Connection BOX Installation Return Return to Section TOC Spool GUN Connection Spool GUN Preparation Making a Weld with the Spool GUN Adapter K607-1 Installed Making the Weld Timer KIT K585-1 Drive Roll Kits Steel Wire Sizes Part NumberAluminum Wire Sizes To Make Spot Plug Welds Maintenance Routine and Periodic Maintenance Perform the following daily Maintenance Drive Rolls and Guide Tubes GUN Tubes and Nozzles Contact TIP and GAS Nozzle InstallationCable Cleaning DROP-IN Reel Spindle and Clips Liner Removal Replacement Figure D.2 Liner maintenance GUN Handle Disassembly To open up the handle Description English Size Metric Size WIRE-MATIC Theory of Operation Input Line Voltage and Main Transformer Output Rectification Feedback Control Constant Voltage Output Figure E.4 Constant Voltage Output Wire Drive Motor Feedback Thermal Protection SCR Operation Figure E.6 SCR Operation WIRE-MATIC Troubleshooting & Repair HOW to USE Troubleshooting Guide Recommended Course of Action Board can be dam- aged by static electricity PC Board Troubleshooting ProceduresElectric Shock can kill Main Transformer Rectifier Assembly Test To Section TOC Perform the SCR Rectifier Perform the Wire Drive Motor Liquid elec Trolyte in these capacitors is Perform the Output Rectifier Materials Needed Main Transformer TestTest Description Main Transformer Test Test Procedure ON/OFF Power Switch will be hot during these tests Main Transformer Test Static SCR Rectifier Assembly Test Leads Figure F.4 SCR 1 Test Points Active SCR Rectifier Assembly Test Leads Figure F.7 SCR Tester Circuit SCR connections Wire Drive Motor and Tachometer Feedback Test Wire Drive Motor and Tachometer Feedback Test Test Procedure Test for Supply Voltage to Tachometer Test for Feedback Voltage to the Control Board Scope Settings Normal Open Circuit Voltage Waveform Machine Loaded to 250 Amps AT 26 VDC Scope Settings Typical Output Voltage Waveform Machine Loaded Machine Loaded to 220 Amps AT 22 VDC Scope Settings Troubleshooting & Repair Typical SCR Gate Voltage Waveform Materials Needed Control PC Board Removal and ReplacementRemoval and Replacement Procedure Removal and REPLACE- Ment Procedure Wire Drive Assembly Removal and Replacement Wire Drive Assembly Removal and Replacement Procedure Figure F.11 Wire Drive Assembly Removal SCR Output Rectifier Removal & Replacement Right side heat sink See Figure F.14 Disconnection Heat Sink Lead Capacitor Bank Removal and Replacement Bank Removal Replacement Components Main Transformer Removal and Replacement Power Switch FAN Motor and FAN Removal and Replacement FAN Motor and FAN Removal and Replacement Procedure Figure F.16 Fan Motor and Fan Removal Components Troubleshooting & Repair Input Volts/Hertz Wire Speed RangeOpen Circuit Voltage 230/60 375 WIRE-MATIC Table of Contents Electrical Diagrams Section WIRE-MATIC Electrical Diagrams Spool GUN Option Wiring Diagram 208/230 Code To Section Available from Lincoln Control PC Board G2332 Layout