caddy arc 251i service manual

0740 800 188 Valid for serial no. 810−xxx−xxxx 090819

Caddy�

Arc 251i

Service manual

S0740 800 188/E090819/P52− 2 −TOCe

Rights reserved to alter specifications without notice.

READ THIS FIRST 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INTRODUCTION 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TECHNICAL DATA 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WIRING DIAGRAM 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Component description 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arc 251i 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DESCRIPTION OF OPERATION 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 MMC unit 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2AP1 EMC board 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2AP2 Power supply board 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2AP2:1 Primary circuit 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2AP2:2 Secondary circuit 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2AP2 Component positions 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15AP1 Power module 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15AP1:1 Switching circuit 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15AP1:2 Gate driver stages 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15AP1:3 Secondary power circuits 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15AP1:4 Temperature monitoring circuits 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15AP1:5 Thyristor firing circuit 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15AP1 Component positions 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17AP1 PFC board 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17AP1:1 Power supply 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17AP1:2 Power factor corrector (PFC) 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17AP1:3 Thyristor firing circuit 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17AP1:4 Temperature monitoring 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17AP1 Component positions 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1 Control board 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:1 Power supply 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:2 Control panel interface circuits 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:3 Remote control input 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:4 Pulse width modulator 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:5 Temperature monitoring 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:6 Shunt and current control amplifier 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:7 Arc voltage feedback 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:8 TIG functions 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:9 Welding process control 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:10 Power−up starting sequence 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1:11 Fan On/Off 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1 Component positions 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20AP1 VRD strapping 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FAULT CODES 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SERVICE INSTRUCTIONS 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

What is ESD? 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Service aid 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Special tools 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Checking power board 15AP1 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Checking PFC board 17AP1 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Soft starting 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Checking the gate pulses 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mounting components on the heat sink 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IN−SERVICE INSPECTION AND TESTING 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General requirements 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Periodic inspection and test 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . After repair, inspection and test 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Visual inspection 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electrical test 45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Functional test 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Test report 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Rights reserved to alter specifications without notice.

INSTRUCTIONS 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAFETY 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INSTALLATION 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Location 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mains power supply 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OPERATION 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Connections and control devices 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overheating protection 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MAINTENANCE 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power source 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FAULT−TRACING 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SPARE PARTS 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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READ THIS FIRSTMaintenance and repair work should be performed by an experienced person, andelectrical work only by a trained electrician. Use only recommended replacement parts.

This service manual is intended for use by technicians with electrical/electronic training forhelp in connection with fault−tracing and repair.

Use the wiring diagram as a form of index for the description of operation. The circuitboards are divided into numbered blocks, which are described individually in more detail inthe description of operation. Component names in the wiring diagram are listed in thecomponent description.

Use the spare parts list as a guide to where the components are located in the equipment.The spare parts list is published as a separate document, see page 51.

This manual contains details of design changes that have been made up to and includingAugust 2009.

The manual is valid for: Arc 251i with serial number 810−xxx−xxxx.

The Arc 251i is designed and tested in accordance with international and Europeanstandards IEC/EN 60974. On completion of service or repair work, it is the responsibility of the person(s)performing the work to ensure that the product still complies with the requirements ofthe above standard.

WARNING!Many parts of the power source are at mains voltage.

CAUTION!Read and understand the instruction manual beforeinstalling or operating.

INTRODUCTION

Caddy Arc 251i is a welding power source intended for MMA and TIG welding, where allsettings are made from the control panel.

Design structure of the power source

Caddy Arc 251i is a microprocessor controlled power source based on the inverter principle.It consists of a number of function modules, as shown in the schematic diagram below.Each module has a module number, which is always included as the first part of thename/identification of components in the module.

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Principle block diagram of the Arc 251i

The modules have the following main functions:

2AP1 EMC moduleThe EMC module suppresses interference to the mains.

17AP1 PFCThe PFC module handles the power factor correction for the power source. The 3 phasevoltage is rectified and feeds a switching circuit that forms a controlled high voltage DCsupply to the power board, 15AP1.

15AP1 Power boardThis module is a forward inverter, operating at a switching frequency of 45 kHz. IGBTtransistors are used as the switching elements. All power semiconductors are built intomodules.

2AP2 Power supply unitThe power supply unit (PSU) is supplied by the PFC module. It generates supply voltagesto the fan, the control board and the switching circuit of the PFC module.

20AP1 Control boardThe control board, 20AP1, checks the status of the control elements of the control paneland controls the function of the power board, 15AP1.

TECHNICAL DATA

Arc 251i

Mains voltage 400 V �15%, 3∼ 50/60 HzMains supply Ssc min 3.3 MVAPrimary current Imax MMAImax TIG

14 A10 A

No−load power demand when in theenergy−saving mode, 6.5 min. after welding 30 W

Setting range MMATIG

4 − 250 A3 − 250 A

Permissible load at MMA30 % duty cycle60 % duty cycle 100% duty cycle

250 A / 30 V190 A / 27.6 V150 A / 26 V

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Arc 251i

Permissible load at TIG30 % duty cycle60 % duty cycle 100% duty cycle

250 A / 20 V190 A / 17.6 V150 A / 16 V

Power factor at maximum currentMMATIG

0.94 0.93

Efficiency at maximum currentMMATIG

83 %79 %

Open−circuit voltagewithout VRDwith VRD

62 V<35 V

Operating temperature −10 to +40°CTransportation temperature −20 to +55°CConstant sound pressure when idling <70 db (A)Dimensions lxwxh 418 x 188 x 208 mmWeight 10.5 kgInsulation class transformer HEnclosure class IP 23Application class

Mains supply, Ssc minMinimum short circuit power on the network in accordance with IEC 61000−3−12

Duty cycleThe duty cycle refers to the time as a percentage of a ten−minute period that you can weld at a cer-tain load without overloading. The duty cycle is valid for 40°C.

Enclosure classThe IP code indicates the enclosure class, i. e. the degree of protection against penetration by solidobjects or water. Equipment marked IP23 is designed for indoor and outdoor use.

Application class

The symbol indicates that the power source is designed for use in areas with increasedelectrical hazard.

WIRING DIAGRAMThe power source consists of a number of function modules, which are described in thecomponent descriptions on the following pages. Wire numbers and component names inthe wiring diagram show to which module each component belongs.

Wires/cables within modules are marked 100 − 6999.

Wires/cables between modules are marked 7000 − 7999.

Components outside modules − e.g. capacitors − are named such as C1 − C99,connectors XS1 − XS99 (S = socket), XT1 − XT99 (T = terminal).

Circuit boards within each module have names such as 20AP1 − 20AP99.

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20 = module association, 1−69AP = circuit board1 = individual identification number, 0−99

Transistors within particular modules have identification numbers such as 15Q1 −15Q99.

15 = module association, 1−69Q = transistor1 = individual identification number, 0−99

Component descriptionComponent Description

1 MMC module. This module is described in separate manuals for thecontrol panels.

2 Mains module. Wire numbers 200 − 299.

2AP1 EMC board, see page 11.

2AP2 Power supply board, see page 12.

2QF1 Main switch.

2L1 − 2L5 Ferrite ring cores.

15AP1 Power board, see page 16.

15AP2 LC−filter board, see page 17

15TM1 Main transformer

15L2 Inductor, welding circuit.

15ST1 Thermal switch in the winding of 15L2.

15D1 − 15D3 Diode modules Each module consists of two diodes. Two diodes are rectifier diodes, one from 15D1 and one from 15D2.Three diodes are frewheel diodes, one from each module.One diode from 15D3 is a filterdiode.

See page 41 for assembly instructions.

15EV1 Fan.

15RS1 Shunt. 119 �1 mV at 250 A

17AP1 PFC board, see page 20.

17L1 PFC inductor

20AP1 Control board, see page 23.

CAUTION !STATIC ELECTRICITY can damage circuitboards and electronic components.� Observe precautions for handling electrostatic−

sensitive devices.

� Use proper static−proof bags and boxes.ESD

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Placement of the circuit boards

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Arc 251i

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DESCRIPTION OF OPERATIONThis description of operation describes the function of circuit boards and other componentsin the equipment. It is divided into sections, numbered to correspond to the circuit boardnumbers and divisions into function blocks.

1 MMC unit

The MMC unit consists of a operator’s control panel and a display board. The MMC is usedfor setting and displaying welding data. The welding data are stored by the control board,20AP1.

The control panel consists of pushbuttons, control knob, LEDs and a 3−digit display.

The control panels are described in separate instruction and service manuals.

The control panels are:

� A32 intended for MMA− and DC TIG−welding

� A34 intended for MMA− and DC TIG−welding.

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2AP1 EMC board

The combination of coils and capacitors prevents interference from the inside of themachine to reach the electric mains network.

Circuit diagram

WARNING!,Dangerous voltage − mains voltage.

Component positions

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2AP2 Power supply board

The power supply board receives rectified mains voltage, about 565 V DC, from the PFCboard. From this it generates supply voltages for the power source.

2AP2:1 Primary circuit

WARNING! Dangerous voltage − mains voltage.

The primary circuit is supplied at 565 V DC from the PFC board, 17AP1.

Transistors Q1 and Q2 are the switching elements in a switched voltagesupply. The sensing circuit uses the secondary voltage +24V that is connectedto IC5. Through optocoupler IC2, IC5 controls switch regulator IC3, whichgenerates gate pulses to Q1 and Q2, via TR1.

+15VA and 0VAInternal power supply for the 2AP2 and for circuits on the 17AP1 and 15AP1. It is regulated to 15�0.75 V by VR3. It is part of the primary side as it sharesthe 0VA with the 565 V supply voltage.

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2AP2:2 Secondary circuit

The output voltages can be tested by the SST 3, see soft−starting on page 38.

+13VB and 0VBUnregulated voltage at 13�1.5 V with galvanic isolation, used for remotecontrol.

+5V and 0VThe voltage is regulated by VR1 to 5�0.25 V.

+24V and 0VThis voltage is regulated to 24�0.75 V by IC3 on the primary side togheterwith IC5 on the secondary side.

−15V and 0VThis voltage is regulated to −15�0.75 V by VR4.

Fan On/OffThe fan, 15EV1, is supplied at +24V. It is controlled by 20AP1 with the signalFan On/Off. See also “20AP1:11 Fan On/Off” on page 29.

Early warning power shut downIf the voltage goes low, the output CN1:8 generates a warning signal to theprocessor on the control board 20AP1. The control board AP201 then shutsdown in a controlled manner.

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2AP2 Component positions

WARNING!Dangerous voltage − mains voltage. The shaded area is at mains voltagepotential.

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15AP1 Power module

Power module main circuits

WARNING!Dangerous voltage − mains voltage. Never make any measurements on this boardwhen the machine is connected to the mains supply.

The power module is a single forward converter, operating at a switching frequency of 45 kHz with IGBT transistors as the switching elements.

The power board carries the gate circuit and the switching circuit. The switching transistorsare integrated in a semiconductor module, PM1, which is part of the power board.

See page 40 for screen traces of waveforms and measurement instructions.

On page 34 there are instructions on how to check the power board.

If the power board has failed, a replacement board must be mounted in accordance with theinstructions on page 41.

15AP1:1 Switching circuit

The switching transistors are integrated in the semiconductor module, PM1.They are connected in parallel four and four.

15AP1:2 Gate driver stages

Transformer TR1 is a gate driver transformer for galvanic isolation of the drivecircuits from circuit board 20AP1. The gate pulses are measured on circuitboard 20AP1, see instructions on page 40.

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15AP2, circuit diagram and component positions

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15AP1:3 Secondary power circuits

The secondary power circuits are: transformer 15TM1, diode modules15D1,15D2,15D3, inductor 15L2 and LC filter 15AP2.

Diode modulesEach diode module consists of two diodes. Two diodes are rectifier diodes, one from 15D1 and one from 15D2.Three diodes are frewheel diodes, one from each module.One diode from 15D3 is a filterdiode.

During the time interval between two voltage pulses from transformer 15TM1,the freewheel diodes maintain the welding current from inductor 15L2.

If a diode module has failed, a replacement module must be fitted inaccordance with the instructions on page 41.

15AP2 Filter boardInductor L1 forms an LC circuitwith C1//C2 and D2 to reducethe risk of arc extinction at lowwelding currents.

When rectifier diodes15D1//15D2 conducts, the LCcircuit charges up.

The circuit is capable oftemporarily maintaining a higharc voltage at low current.

Diode D2 prevents capacitor C1//C2 from going negative.

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15AP1:4 Temperature monitoring circuits

WARNING!Dangerous voltage − mains voltage. +15VA, +14VA, +5V1A and 0VA are atmains voltage potential.

The control board, 20AP1, uses a digital input to monitor the temperatures ofthe power source. The temperature feedback from the NTC resistors on thePFC and power boards is analogue. The monitoring circuits on the powerboard handles the threshold levels and hysteresis of the temperaturemeasument.

See also “20AP1:5 Temperature monitoring” on page 25.

15AP1:5 Thyristor firing circuit

See “17AP1:3 Thyristor firing circuit” on page 21.

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17AP1 PFC board

The PFC board consists of the main rectifier, the thyristor firing circuit, the temperaturecircuit and the PFC control circuit.

If the PFC board has failed, a replacement board must be mounted in accordance with theinstructions on page 42.

On page 36 there are instructions on how to check the PFC board.

WARNING!Dangerous voltage − mains voltage. All parts of this circuit board are at mainsvoltage potential.

17AP1 main circuits

17AP1:1 Power supply

The three−phase mains voltage is rectified by semiconductor module PM1.

When the power source is in idle mode, the rectified voltage (565 V) issupplied through the charging resistors, R78 and R79. In welding mode thethyristor in PM1 by−passes the resistors. If the thyristor did not conduct,resistors R78 and R79 would burn out when the unit is in welding mode.

The 565 V supplies the PFC circuit that boosts the voltage to 710 V.

17AP1:2 Power factor corrector (PFC)

The aim with the power factor corrector is to keep the mains current in phasewith the mains voltage. The PFC circuit holds the intermediate voltage(+DCbus) at 710 V. If the PFC circuit does not work the intermediate voltage is565 V or less.

When the PFC is working properly, the voltage across the DCbus is 710 V.

S0740 800 188/E090819/P52− 21 −ch34_17

17AP1:3 Thyristor firing circuit

When the mains power supply is turned on and during idle mode the thyristorin PM1 is off.

When the switching circuit on power board 15AP1 receives gatepulses fromthe control board, the firing circuit turns on the thyristor in PM1 so that itby−passes the charging resistors.

17AP1:4 Temperature monitoring

The PM1 module havs a built−in NTC−resistor that monitors the internaltemperature. It is connected to the temperature circuits on the power board.

See “15AP1:4 Temperature monitoring” on page 18 and “20AP1:5 Temperature monitoring” on page 25.

S0740 800 188/E090819/P52− 22 −ch34_17


S0740 800 188/E090819/P52− 23 −ch34_20

20AP1 Control board

The processor on the control board monitors and controls the various functions of the powersource. It obtains information on welding data from the control panel. If the circuit board is faulty, it must be replaced. After replacing the circuit board, soft−startthe machine. See the instructions on page 38.

Note! There are jumpers on the board that must be moved to the replacement board, seepage 30.

20AP1:1 Power supply

+5 V and +2.5 V

IC6 monitors the 24 V voltage supply to the 5 V regulator on circuit board2AP2. IC16 monitors the 5 and 2.5 V supplies. Regulator VR4 supplies theprocessor with +2.5 V.

The voltage on terminal PF6 is normally about 24 V, when this drops below 20 V, pin 14 of IC6 goes low, providing the processor with a low power supplyvoltage signal. The processor then stores current data and generates faultcode E4. When the 5 and 2.5 V voltages are passing below their tresholdvalues, the processor receives a reset signal from IC16.

Fault code E4 is not displayed at normal power off

+15 V and +20 V

Voltage regulator VR2 produces an output voltage of +20 �1.0 V, whichsupplies the pulse width modulator output stage.

Voltage divider R70/R75 supplies 2.6 V to the processor. This provides a signalthat the power supply is available.

Voltage regulator VR1 produces an output voltage of +15 V, and this, togetherwith the −15 V supply, powers the analogue circuits.

S0740 800 188/E090819/P52− 24 −ch34_20

−15 V

The −15 V power supply is monitored by the processor.

+10 VB

Voltage regulator VR3 produces a stabilised +10 V supply, which is used tosupply the remote control unit. This supply is referred to as +10 VB, and itsneutral point, 0 VB, is separated from the electronic neutral (0 V).Potentiometer R56 is used to adjust the voltage.

20AP1:2 Control panel interface circuits

See the service manual for the A32/A34 control panels.

20AP1:3 Remote control input

If the remote control input is activated, but there is no reference signal, resistorR54 holds the reference input low. This results in a welding current of 3 A forTIG welding and 4 A for MMA welding.

S0740 800 188/E090819/P52− 25 −ch34_20

20AP1:4 Pulse width modulator

The pulse width modulator determines the frequency and pulse time of theswitching transistors’ control pulses. IC3 controls the pulse frequency, thepulse time and inhibition of pulses.

The pulse frequency is 45 kHz +/− 1kHz, with a maximum pulse width of 43 −44 % of the cycle width. See page 40 for screen traces of waveforms andmeasurement instructions.

Transistor Q5 controls the primary winding of the pulse transformer on circuitboard 15AP1.

20AP1:5 Temperature monitoring

Principle diagram of the temperature monitoring circuits

The temperature monitoring circuit operates when the temperature exceedsone of the threshold temperatures as decribed below.

If the monitoring circuit operates, the power source is stopped. The powersource cannot be restarted until it has cooled sufficiently.

15NTC_PM1 is fitted inside semiconductor module PM1 of the power board,15AP1. The treshold temperature is 95�C and it resets at 62�C.

17NTC_PM1 is fitted inside semiconductor module PM1 of the PFC board,17AP1. The treshold temperature is 88�C and it resets at 60�C.

Thermal overload switch 15ST1 is fitted in the winding of inductor 15L2. Itopens at 140�C.

S0740 800 188/E090819/P52

VRD strapping

− 26 −ch34_20

20AP1:6 Shunt and current control amplifier

The shunt produces 119 mV at a welding current of 250 A. The shunt responseis linear to the welding current.

If the shunt is not connected to the circuit board, resistor R2 supplies about 1.4 to 1.9 V to the shunt input. This blocks the current control amplifier, i.e. themachine does not deliver any welding current.

20AP1:7 Arc voltage feedback

This circuit measures and scales the arc voltage to a suitable level for theprocessor. 64 V arc voltage produces a voltage signal of 5.0 V at the cathodeof diode D13.

Open−circuit voltage controlThe open−circuit voltage control holds the voltage at 50 − 64 V.When the VRD (Voltage Reduction Device) function is active, the open−circuitvoltage is < 35 V (19 − 30 V). The VRD function can only be activated ordeactivated by changing the strapping of the control board, see the circuitdiagram below and the component positions diagramon page 30.

Note! Spare part boards are delivered with VRDinactive.

S0740 800 188/E090819/P52− 27 −ch34_20

MMA� The machine generates the actual open−circuit voltage, see: “Open−circuit

voltage control” above.� Touch the electrode on to the workpiece. When the open−circuit voltage

goes below 45 V (16 V when VRD is active), the open−circuit voltagecontrol is disabled.

� When the current exceeds 8 A the hot start current is activated.� When the arc voltage exceeds 52 V, welding stops and the open−circuit

voltage control is activated.

When the welding arc extinguishes the open circuit voltage is about 120 V,peak voltage. Within 0.3 seconds the open−circuit voltage control reduces thevoltage to about 60 V, peak voltage, (30 V when VRD is active).

TIGSee: “20AP1:8 TIG functions” below.

20AP1:8 TIG functions

Live TIG start� The machine generates the actual open−circuit voltage, see: “Open−circuit

voltage control” above.� Touch the electrode on to the workpiece. The machine produces a current

of about 24 A.� Lift the electrode from the workpiece. The arc strikes, the open−circuit

voltage control is deactivated and the current increases to 30 A.� When the arc voltage exceeds 8 V, the current increases / decreases to

the set current.� If the arc voltage is above 45 V for more than 100 milliseconds the

open−circuit voltage control is activated.

When the welding arc extinguishes the open circuit voltage is about 120 V,peak voltage. Within 0.3 seconds the open−circuit voltage control reduces thevoltage to about 60 V, peak voltage, (30 V when VRD is active).

Terminal TIG

Terminal TIG, shown above, is not used in this application. Terminals TIG1 and TIG5 are used for power supply during soft−starting, see page 38.

S0740 800 188/E090819/P52− 28 −ch34_20

20AP1:9 Welding process control

The processor inputs are the set values of welding data and the arc voltage.The processor also calculates a set value signal for welding current, andsupplies this to the current control amplifier.

The process regulator control principle

Hot start MMA

Time

Cu

rren

t

Peak current

Adjustable starting current

Set current

1 2Starting current, MMA welding mode1. Phase 1, fixed starting current depending on the set current.2. Phase 2, hot start = adjustable starting current.

MMA normal welding modeIn the MMA normal welding mode, the welding current is briefly increased atthe start of welding. The peak current, phase 1 in the diagram above, isengaged for 150 milliseconds.

The peak current is twice the normal welding current up to 150 A (i.e. twice theset value), subject to a maximum of 350 A.

The hot start current, phase 2 above, is engaged for 1.5 seconds. It is set inper cent of the set current, but does never exceed the peak current.

MMA drop welding modeIn the MMA drop welding mode, the peak current is three times the set value,but the duration is shorter at only 50 ms.

The hot start current, phase 2 above, is engaged for 240 milliseconds. It is setin per cent of the set current, but does never exceed the peak current.

S0740 800 188/E090819/P52

LEDs on circuit board 20AP1

− 29 −ch34_20

20AP1:10 Power−up starting sequence

On power−up, the board’s CAN controller reads in the bus speed from themicro processor: 400 kbit/s.

The circuit board displays the startingsequence from power−up.LED1 lights red. Then LED1, LED2 andLED3 lights green. When the board has been initiated, and thepower source is in the application program,LED1 flashes continously with a green light.

20AP1:11 Fan On/Off

The fan is controlled by the control signal Fan On/Off. The signal is connectedto a power transistor on 2AP2 that switches the power to the fan on or off. See also “Fan On/Off” on page 13.

The fan starts when the mains switch is turned on and runs for seven seconds.It starts when welding starts and continues to run six and a half minutes afterwelding is finished.

S0740 800 188/E090819/P52− 30 −ch34_20


Note! There must be a jumper between pin 5 and 6 on terminal RS.

20AP1 VRD strapping

Strap terminal A1 and A2 to activate the VRD function.Strap terminal A2 and A3 to deactivate the VRD function.

See also item 20AP1:7 Arc voltage feedback on page 26.

S0740 800 188/E090819/P52− 31 −ch34f1

FAULT CODES

Code Description

E04 5 V power supply too low

The unregulated power supply voltage (+24 V) is too low: the smoothing capacitors cannotkeep the voltage up enough for the processor to continue to operate. The processor stops allnormal activities, expecting to be shut down.

Action: Turn off the mains power supply to reset the unit. If the fault persists, check thepower supply to circuit board 20AP1.

E06 High temperature

The temperature monitoring circuit has operated. The power source is stopped, and cannotbe restarted until the circuit has reset. See also page 25.

Possible causes: Overloading, fan not working properly, cooling air inlets or outlets blockedor obstructed or dirt on the heat exchanger.

E11 Current servo faultAutomatic reset when the fault has cleared. May also be reset by pressing any pushbutton.

E16 High no−load voltage, VRD error

The open circuit voltage is too high.

Action: Turn off the mains power supply to reset the unit. Check the arc voltage monitoringcircuits, see diagram on page 26. If the fault persists replace circuit board 20AP1.

E19 Error in persistent memory

Action: Restart the machine. If the fault persists, replace circuit board 20AP1.

S0740 800 188/E090819/P52− 32 −ch34f2

SERVICE INSTRUCTIONS

What is ESD?

A sudden transfer or discharge of static electricity from one object to another. ESD stands forElectrostatic Discharge.

How does ESD damage occur?

ESD can cause damage to sensitive electrical components, but is not dangerous to people.ESD damage occurs when an ungrounded person or object with a static charge comes intocontact with a component or assembly that is grounded. A rapid discharge can occur,causing damage. This damage can take the form of immediate failure, but it is more likelythat system performance will be affected and the component will fail prematurely.

How do we prevent ESD damage?

ESD damage can be prevented by awareness. If static electricity is prevented from buildingup on you or on anything at your work station, then there cannot be any static discharges.Nonconductive materials (e.g. fabrics), or insulators (e.g. plastics) generate and hold staticcharge, so you should not bring unnecessary nonconductive items into the work area. It is obviously difficult to avoid all such items, so various means are used to drain off anystatic discharge from persons to prevent the risk of ESD damage. This is done by simpledevices: wrist straps, connected to ground, and conductive shoes.

Work surfaces, carts and containers must be conductive and grounded. Use only antistaticpackaging materials. Overall, handling of ESD−sensitive devices should be minimized toprevent damage.

CAUTION !STATIC ELECTRICITY can damage circuitboards and electronic components.� Observe precautions for handling electrostatic−

sensitive devices.

� Use proper static−proof bags and boxes.ESD

S0740 800 188/E090819/P52− 33 −ch34f2

Service aid

We can offer a number of service tools that will simplify the service.

Antistatic service kit

Ordering no. 0740 511 001

The kit makes it easier to protect sensitvecomponents from electrostatic discharge.

Contents:

� A conductive mat (size 610 x 610 mm)

� A 1.5 metre long ground cable with acrocodile clip

� An adjustable wrist strap and cable withan inbuilt protective resistor

Antistatic service kit

Special tools

Soft−starting tool SST 3The soft−starting tool SST 3 is made for ESAB’s single phase inverters and for 3−phaseinverters with 250 A output current. Ordering no. 0459 534 881

Functions for single phase inverters Functions for 3 phase inverters� Soft−starting rectifier � Voltage adapter with current limit� Voltage adapter with current limit � Voltage−test board� Voltage−test board � Gate pulse load with test terminals� Gate pulse load with test terminals � Temperature monitoring override jumper� Shunt voltage resistor. For single phase

inverters with analogue control board: Arc 151i A31, Arc 152i A31 and OrigoArc

Test box TB 1To be used for in−service inspection and testing.

Ordering no. 0460 868 880

S0740 800 188/E090819/P52− 34 −ch34f_15ap1

Checking power board 15AP1

1. Disconnect the welding power source from the mains supply.

2. Dismantle the cover.

3. Measure the forward voltage drop of the freewheel diodes in the PM1 module.

a. Connect the positive pole of the multimeter to CN4 and the negatve pole to CN5. The voltage drop must be 0.35 to 0.6 V.

b. Connect the positive pole of the multimeter to CN6 and the negatve pole to CN3. The voltage drop must be 0.35 to 0.6 V.

4. Measure the resistance across gate and source of the transistors in the PM1 module.

a. Connect the negative pole of the ohmmeter to CN5 and the positive to PM1:9,PM1:10, PM1:12 and PM1:13 respectively. The resistance must be higher than 100 kohm.

b. Connect the negative pole of the ohmmeter to CN4 and the positive to PM1:18,PM1:19, PM1:21 and PM1:22 respectively.The resistance must be higher than 100 kohm.

5. Measure the resistance of the NTC−resistor in PM1. Measure between PM1:23 and PM1:24. The resistance must be 1.5 to 2.0 kohm at an ambient temperature of about 20�C.

S0740 800 188/E090819/P52− 35 −ch34f_15ap1

Measuring points for 15AP1

S0740 800 188/E090819/P52− 36 −ch34f_17ap1

Checking PFC board 17AP1



3. Measure the forward voltage drop of the diodes of the rectifier bridge. The voltage drop must be 0.4 to 0.6 V.

a. Connect the negative pole of the multimeter to R78 and the positive pole to CN1,CN4 and CN6 respectively.

b. Connect the positve pole of the multimeter to CN3 and the negative pole to CN1,CN4 and CN6 respectively.

4. Unscrew and remove the two screws that are connecting 17L1 to the circuit board.Insulate the terminals of 17L1 from the circuit board by fitting the tip of a plastic cabletie, or similar, between the connection terminals of 17L1 and the circuit board.

a. Measure the forward voltage drop of diode PM1:D1. Connect the positve pole of the multimeter to R79 and the negative pole to CN2.The voltage drop must be 0.4 to 0.6 V.

b. Measure the forward voltage drop of diode PM1:D2. Connect the positve pole of the multimeter to 17L1 and the negative pole to CN2.The voltage drop must be 0.7 to 0.9 V.

5. Connect 17L1 to the circuit board, tighten the connection screws to a torque of 4.5 Nm.

6. Measure the resistance across the charge resistors R78 and R79.The resistance must be about 24 ohm.

7. Measure the resistance of the NTC−resistor in PM1.

a. Measure between PM1:5 and PM1:6. The resistance must be 1 to 2 kohm at an ambient temperature of about 20�C.

b. Disconnect the ribbon cable from terminal CN5.

c. Measure between PM1:5 and PM1:6.The resistance must be 5.5 to 6.5 kohm at an ambient temperature of about 20�C.

d. Reconnect the ribbon cable to terminal CN5.

8. Connect the power source to the mains and switch it on.

9. Measure the rectified mains voltage.Measure between R79 and CN3. The voltage must be 565 V DC (�15%).

10. Measure the output voltage from the PFC board.Measure between CN2 and CN3. The voltage must be 710 V DC (�5%).

11. Checking the thyristor firing circuit.

a. Connect a voltmeter across R78 and R79. The voltage at no load must be about 1.2 V DC.

b. Connect the output of the power source to a resistive load of 200 ohm 100 W (test box TB 1 can be used).

c. Set a welding current of 25 A.The voltage across R78 and R79 must be about 0.8 V DC.

12. Checking voltage 5V1. Measure between TP1 and CN3. The voltage must be 5.1 V DC (�2%).

13. Disconnect the power source from the mains.

14. Reassemble the cover.

S0740 800 188/E090819/P52− 37 −ch34f_17ap1

Measuring points for 17AP1

The circuit diagram of 17AP1 is on page 20.

S0740 800 188/E090819/P52

Placement of the circuit boards

WARNING!TerminalCN2 is atmains volt-age

− 38 −ch34f3soft

Soft startingWe recommend soft starting of the machine after replacing circuit board 20AP1, powersupply board 2AP2 and circuit boards or components in the power module. Soft starting supplies the power board with a low voltage in order to avoid injury to personsor damage to components.

It is a good idea to use soft starting when fault tracing.

Special equipment

To soft−start the machine you need thesoft−starting tool SST 3, this is descrived onpage 33.

WARNING!Dangerous voltage − The PFC board,17AP1, is at mains voltage during thesoft−starting procedure.

Instructions



3. Remove the two copper bars betweenthe PFC board, 17AP1 and the power board, 15AP1. (Connections 17AP1:CN2 to 15AP1:CN5and 17AP1:CN3 to 15AP1:CN6.)

4. Disconnect the ribbon cable from terminal CN1 of thepower supply board, 2AP2.

5. Connect the cable “Voltage test” from SST 3 to terminalCN1 of 2AP2.

6. Connect the power source to the mains supply.

7. Turn the mains switch to ON.

8. Verify the output voltages from 2AP1, all LEDs on theSST 3 must light.

9. Check the +15VA voltage from 2AP2.Measure between terminals CN2:4 and CN2:5 on 2AP2. The voltage must be 15 V �0.75 V.

10. Turn the mains switch to OFF.

11. Reassemble the ribbon cable between the power supply board and the control board.

12. Disconnect the power source from the mains supply.

S0740 800 188/E090819/P52− 39 −ch34f3soft

13. Connect SST 3 for soft starting of 15AP1.

a. Connect cable 20AP1 TIG to terminal TIG of the control board.

Connection of the SST 3 tothe control board

b. Connect cable 15AP1 CN5 to terminal CN5 of the power board.

c. Connect cable 15AP1 CN6 to terminal CN6 of the power board.

Connection of the SST 3 tothe power board

14. Connect the power source to the mains supply.

15. Turn the mains switch to ON.

16. Set the power source to MMA mode.

17. Measure the supply voltage to 15AP1.Measure between CN5 (+) and CN6 (−). The voltage must be 22 to 25 V DC.

18. Measure the voltage across the welding outlets. The voltage must be about 4 V DC.

Circuit connections and measuring points for soft starting

19. Turn the mains switch of the welding power source to OFF.

20. Disconnect the power source from the mains supply.

21. Disconnect SST 3.

22. Reassamble the two copper bars between the PFC board and the power board.(Connections 17AP1:CN2 to 15AP1:CN5 and 17AP1:CN3 to 15AP1:CN6.)

23. Reassemble the cover.

S0740 800 188/E090819/P52− 40 −ch34f3gate

Checking the gate pulses

When checking the gate pulses, the machine can either be in soft−starting mode or innormal operation mode.

Special equipment

To measure the gate pulses, you need a gate pulse load. This is included in soft−startingtool SST3, which is described on page 33.

Instructions

1. Disconnect the machine from the mains.

2. Disconnect connector 20XS5 from terminal G on control board 20AP1.

3. Connect the gate pulse test cable of the SST 3 to terminal G on control board 20AP1.

4. Disconnect connector 20XS1 from terminal T on control board 20AP1.

Measuring connection for the gate pulses

5. Connect the temperature−switch jumper to terminal T on control board 20AP1.

6. Switch on the machine.

7. Connect an oscilloscope to the SST 3, with the probe to terminal G2 and the screen toterminal G1 of SST 3.

8. Set the machine to MMA welding mode.

9. Measure the pulse frequency. It must be 45 kHz +/− 1kHz.

10. Measure the duration of the negative pulse. It must be 41 − 43 % of the cycle time,measured at a voltage level of −10 V.

11. The waveform of the pulses must be as shown below.

Gate pulses from circuit board 20AP1

S0740 800 188/E090819/P52− 41 −ch34f3heat

Mounting components on the heat sinkThermal paste

Apply thermal conducting paste to the components before fitting them to the heat sink.

Start by cleaning the heat sink, and then apply a very thin, even layer of thermal paste tothe contact surfaces of the components. The purpose of the paste is to fill out any hollowsin the surfaces of the components and the heat sink. Those parts of the component and theheat sink that are in true metallic contact may already have good thermal contact.

Mount the components as described below.

See the spare parts list for the order number for thermal paste, roller and roller handle. Useonly the paste recommended by us.

Fitting instructions

15AP1 Power board with semiconductor module

1. Clean the heat sink and apply thermal conducting paste to thesemiconductor module as described above.

2. Fit the board and tighten the screws to a torque of 2.5 Nm, and then furthertighten them to 4.5 Nm.

3. Tighten the screws that connect transformer 15TM1 and copper bars tocircuit board 15AP1 to a torque of 4.5 Nm.

CAUTION!Incorrectly fitted components can cause failure. Do not tighten the screws tomore than 4.5 Nm.

Note! If transformer 15TM1 has to be replaced, the power board must beremoved and then refitted as described above.

15D1,15D2,15D3

Diode modules

1. Clean the heat sink and apply thermal conducting paste to the diodemodule as described above.

2. Fit the module and tighten the screws to a torque of 2.5 Nm, and thenfurther tighten them to 4.5 Nm.

3. Tighten all connections to the copper bars and circuit board 15AP1 to4.5 Nm.


S0740 800 188/E090819/P52− 42 −ch34f3heat

17AP1 PFC board with semiconductor module

1. Clean the heat sink and apply thermal conducting paste to thesemiconductor module as described above.

2. Fit the board and tighten the screws to a torque of 2.5 Nm, and then furthertighten them to 4.5 Nm.

3. Tighten the screws that connect 17L1 and the copper bars to circuit board15AP1 to a torque of 4.5 Nm.


S0740 800 188/E090819/P52− 43 −cz01_general

IN−SERVICE INSPECTION AND TESTINGin accordance with IEC 60974−4.

General requirements

Qualification of test personnelTests of welding power sources can be hazardous and shall be carried out by an expert inthe field of electrical repair, preferably also familiar with welding, cutting and alliedprocesses.

Test conditionsTests shall be carried out at an ambient air temperature between 10 �� and 40 ��

Measuring instrumentsThe accuracy of measuring instruments shall be class 2.5 as a minimum, except for themeasurement of insulation resistance, where the accuracy of the instruments is notspecified but shall be taken into account for the measurement.

The voltmeter shall have an internal resistance of at least 1M� ��

Periodic inspection and test

Periodic inspection and test shall be carried out in accordance with manufacturersinstructions and local regulations. The periodic inspection and test consists of:

� Visual inspection, (see Visual inspection, page 44)

� Electrical test (see Electrical test, page 45)

The inspection and test shall be documented in a test report, (see Test report, page 48).

A signed and dated label shall be attached to the equipment after an approved test.

After repair, inspection and test

After repair, inspection and test shall be carried out according to manufacturers instructionsand local regulations. The after repair, inspection and test consists of:

� Visual inspection, (see Visual inspection, page 44)

� Electrical test (see Electrical test, page 45)

� Functional test (see Functional test, page 47)

The inspection and test shall be documented in a test report, (see Test report, page 48).

A signed and dated label shall be attached to the equipment after an approved test.

S0740 800 188/E090819/P52− 44 −ch34_test

Visual inspection

Disconnect the welding power source from the mains supply.During visual inspection, each safety related function judged as relevant by the testpersonnel, shall be checked for correct operation.

During visual inspection, the following listed items shall be checked:

1. Torch/electrode holder, welding current return clamp.

� missing or defective insulation

� defective connections

� defective, damaged switches

� other damage

2. Mains supply

� defective, damaged cable

� deformed, faulty plug

� broken or thermally damaged plug pins

� ineffective cable anchorage

� cables and plugs unsuitable for the intended use and performance

3. Welding circuit

� defective damaged cable

� deformed, faulty or thermally damaged coupler/sockets

� ineffective cable anchorage

� cables and coupler unsuitable for the intended use and performance

4. Enclosure

� missing or damaged parts

� unauthorised modifications

� cooling openings blocked or missing air filters

� signs of overload and improper use

� missing or defective protective covers

� missing or defective lifting means, holder etc

� conductive objects placed in the enclosure

5. Controls and indicators

� defective switches, meters and lamps

6. General condition

� poor legibility of markings and labelling

� other damage or signs of improper use

S0740 800 188/E090819/P52− 45 −ch34_test

Electrical test


2. Check continuity of the protective circuit.

Measure the resistance of the protective circuit from the screw (1) tothe protective earth connection in the the mains plug (2).

During the measurement the cable shall be bent, flexed and twistedalong the whole length in order to detect interuptions in theprotective conductor.

� Required value for cables up to 5 m, max 0.3 ��

3. Check the insulation resistance with an insulation tester withthe measurement voltage set to 500 VDC.

a. Turn the mains switch of the the welding power source to ON.

b. Measure from the supply pins in the mains plug (2) to thewelding outlets (3,4).

� Required value not less than 5 M��

c. Measure from the welding outlets (3,4) to the protective earth connection in themains plug (2).

� Required value not less than 2.5 M��

d. Measure from the supply pins in the mains plug (2) to the protective earthconnection in the mains plug (2).

� Required value not less than 2.5 M��

e. Turn the mains switch of the the welding power source to OFF.

4. Check the no−load voltage.

Use the ESAB test box TB 1. If the welding power source has an activated VRDfunction then proceed to step 5.

a. Connect the positive (3) and negative (4) welding outlets to the positive andnegative terminals (DCIN) of the TB 1.

b. Connect a voltmeter to VPEAK of the TB 1.

c. Connect the welding power source to the mains supply.

d. Turn the control knob of the TB 1 anti−clockwise to 0.2.

e. Turn the mains switch of the the welding power source to ON.

f. Set the welding current control on the welding power souce to maximum.

g. Slowly turn the control knob of the TB 1 clockwise from 0.2 to 5.2 while checkingthe voltmeter for the highest value.

� Measured value shall not exceed the allowable value 113 VPEAK

h. Turn the mains switch of the the welding power source to OFF.

i. Disconnect the welding power source from the mains supply.

5. Check of no−load voltage with the VRD activated.

Use the ESAB test box TB 1. This test is only conducted when the VRD function isactivated.

S0740 800 188/E090819/P52− 46 −ch34_test

a. Connect the positive (3) and negative (4) welding outlets to the positive andnegative terminals (DCIN) of the TB 1.

b. Connect a voltmeter to VPEAK of the TB 1.

c. Connect the welding power source to the mains supply.

d. Turn the control knob of the TB 1 anti−clockwise to 0.2.


f. Set the welding current control on the welding power souce to maximum.

g. Check the voltage with the voltmeter.

� Measured value shall not exceed 35 V.

h. Check that the LED indicates active VRD function by a steady green light.

i. Turn the mains switch of the the welding power source to OFF.

j. Disconnect the welding power source from the mains supply.

Test box TB 1

Circuit diagram of the TB 1

S0740 800 188/E090819/P52− 47 −ch34_test

Functional test

1. Each safety related function judged as relevant by the test personnel shall bechecked for correct operation.

Conformity shall be checked by operating the device and by checking whether thewelding power source operates correctly.

2. Check the supply circuits on/off switching device

a. Disconnect the welding power source from the mains supply.

b. Remove the cover

c. Turn the mains switch of the the welding power source to OFF.

d. Measure from the supply pins of the mains plug to the EMCboard, 2AP1.

� Measure L1−CN2:3. Required value, open circuit




f. Measure from the supply pins in the mains plug to the EMCboard 2AP1.

� Measure L1−CN2:3. Required value, less than 0.5 �



g. Reassemble the cover.

3. Check signal and control lamps

Check the function of the display indicators by turning on the unit and visually check thefront panel.

The LED test starts with all LEDs dark, then the diodes are turned on and off, one at atime, until all diodes have been tested. If the test detects a fault, no fault code will belogged. Then the display test is made in the same way as the LED test but for each segment ofthe digits in the display. If the test detects a fault, no fault code will be logged.Finally the software version of the welding data unit is displayed.

4. Check the function of the welding power source by welding.


6. Write the test report.

See Test report, page 48).

7. If the unit passes all the tests, attach appropriate label with signature and date ofthe test.

S0740 800 188/E090819/P52− 48 −cz01_testreport

Test report

Company: Location:

Equipment: Arc welding power source Serial number:

Manufacturer: ESAB Type:

Testing equipment:

VISUAL INSPECTION PASSED

ELECTRICAL TEST Limit Measured valuesProtective conductor resistance ≤ 0.3 Ω

Insulation resistance ÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉInput circuit/

Welding circuit (500 VDC)≥ 5 MΩ

Welding circuit/Protective circuit (500 VDC)

≥ 2.5 MΩ

Input circuit/Protective circuit (500 VDC)

≥ 2.5 MΩ

No−load voltageÉÉÉÉÉÉÉÉ

ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ

without VRD Vpeak

≤113 VDC

with VRD activated Vpeak

≤35 VDC

Electrical test PASSED

FUNCTIONAL TEST PASSED

Remarks

Date

Tested by Signature

Testing company

S0740 800 188/E090819/P52− 49 −ch34i1

INSTRUCTIONS

This chapter is an extract from the instruction manual for the Arc 251i.

SAFETY

CAUTION!Read and understand the instruction manual beforeinstalling or operating.

INSTALLATION

Location

Place the power source so that its cooling air inlets and outlets are not obstructed.

Mains power supply

Note!Mains supply requirementsHigh power equipment may, due to the primary current drawn from the mains supply, influence thepower quality of the grid. Therefore connection restrictions or requirements regarding themaximum permissible mains impedance or the required minimum supply capacity at the interfacepoint to the public grid may apply for some types of equipment (see technical data). In this case itis the responsibility of the installer or user of the equipment to ensure, by consultation with thedistrubution network operator if necessary, that the equipment may be connected.

Make sure that the welding power source is connected to the correct supply voltage andthat it is protected by the correct fuse rating. A protective earth connection must be made inaccordance with regulations.

Recommended fuse sizes and minimum cable area

Mains voltage 400V

Mains cable area mm2 4 G 1.5

Phase current I1eff 8 A

Fuse

anti−surge

type C MCB10 A

10 A

NOTE! The cable area and fuse rating above comply with Swedish regulations. Use the weldingpower source in accordance with the relevant national regulations.

S0740 800 188/E090819/P52− 50 −ch34i1

OPERATION

Connections and control devices

1 Mains voltage switch 4 Connection for remote control unit

2 Connection (+) MMA: welding cable or return cableTIG: return cable

5 Control panel, see separate instruction manual

3 Connection (−) MMA: return cable or welding cable TIG: torch

Overheating protection

The welding power source has overheating protection that operates if the temperaturebecomes too high. When this occurs the welding current is interrupted and a fault code isdisplayed on the control panel.

The overheating protection resets automatically when the temperature has fallen.

MAINTENANCE

Regular maintenance is important for safe, reliable operation.

Only those persons who have appropriate electrical knowledge (authorized personnel) mayremove the safety plates.

CAUTION!All guarantee undertakings from the supplier cease to apply if the customer himselfattempts any work in the product during the guarantee period in order to rectify any faults.

S0740 800 188/E090819/P52− 51 −ch34i1

Power source

Check regularly that the welding power source is not clogged with dirt.

How often and which cleaning methods apply depend on:

� the welding process

� arc times

� placement

� the surrounding environment.It is normally sufficient to blow down the power source with dry compressed air (reducedpressure) once a year.

Clogged or blocked air inlets and outlets otherwise result in overheating.

FAULT−TRACING

Try these recommended checks and inspections before sending for an authorized servicetechnician.

Type of fault Corrective action

No arc. � Check that the mains power supply switch is turned on.� Check that the welding current supply and return cables are

correctly connected.� Check that the correct current value is set.� Check the mains power supply fuses.

The welding current isinterrupted during welding.

� Check whether the thermal cut−outs have tripped (a faultcode is displayed on the control panel).

� Check the mains power supply fuses.

The thermal cut−out tripsfrequently.

� Make sure that you are not exceeding the rated data for thewelding power source (i.e. that the unit is not beingoverloaded).

� Check that the welding power source is not clogged with dirt.

Poor welding performance. � Check that the welding current supply and return cables arecorrectly connected.

� Check that the correct current value is set.� Check that the correct electrodes are being used.

SPARE PARTSThe spare parts list is published in a separate document that can be downloaded from theinternet: www.esab.com

Product FilenameArc 251i 0459 839 021

ESAB ABSE−695 81 LAXÅSWEDENPhone +46 584 81 000

www.esab.com

081016

ESAB subsidiaries and representative offices

EuropeAUSTRIAESAB Ges.m.b.H Vienna−Liesing Tel: +43 1 888 25 11 Fax: +43 1 888 25 11 85

BELGIUMS.A. ESAB N.V. Brussels Tel: +32 2 745 11 00 Fax: +32 2 745 11 28

THE CZECH REPUBLICESAB VAMBERK s.r.o. VamberkTel: +420 2 819 40 885 Fax: +420 2 819 40 120

DENMARKAktieselskabet ESAB HerlevTel: +45 36 30 01 11 Fax: +45 36 30 40 03

FINLANDESAB Oy Helsinki Tel: +358 9 547 761 Fax: +358 9 547 77 71

FRANCEESAB France S.A. Cergy Pontoise Tel: +33 1 30 75 55 00 Fax: +33 1 30 75 55 24

GERMANYESAB GmbH Solingen Tel: +49 212 298 0 Fax: +49 212 298 218

GREAT BRITAINESAB Group (UK) Ltd Waltham Cross Tel: +44 1992 76 85 15 Fax: +44 1992 71 58 03

ESAB Automation Ltd Andover Tel: +44 1264 33 22 33 Fax: +44 1264 33 20 74

HUNGARYESAB Kft Budapest Tel: +36 1 20 44 182 Fax: +36 1 20 44 186

ITALYESAB Saldatura S.p.A. Mesero (Mi) Tel: +39 02 97 96 81 Fax: +39 02 97 28 91 81

THE NETHERLANDSESAB Nederland B.V. Amersfoort Tel: +31 33 422 35 55Fax: +31 33 422 35 44

NORWAYAS ESAB Larvik Tel: +47 33 12 10 00 Fax: +47 33 11 52 03

POLANDESAB Sp.zo.o.Katowice Tel: +48 32 351 11 00Fax: +48 32 351 11 20

PORTUGALESAB Lda Lisbon Tel: +351 8 310 960Fax: +351 1 859 1277

SLOVAKIAESAB Slovakia s.r.o. Bratislava Tel: +421 7 44 88 24 26 Fax: +421 7 44 88 87 41

SPAINESAB Ibérica S.A. Alcalá de Henares (MADRID)Tel: +34 91 878 3600Fax: +34 91 802 3461

SWEDENESAB Sverige AB Gothenburg Tel: +46 31 50 95 00 Fax: +46 31 50 92 22

ESAB international AB Gothenburg Tel: +46 31 50 90 00 Fax: +46 31 50 93 60

SWITZERLANDESAB AG Dietikon Tel: +41 1 741 25 25 Fax: +41 1 740 30 55

North and South AmericaARGENTINACONARCO Buenos Aires Tel: +54 11 4 753 4039 Fax: +54 11 4 753 6313

BRAZILESAB S.A. Contagem−MG Tel: +55 31 2191 4333 Fax: +55 31 2191 4440

CANADAESAB Group Canada Inc.Missisauga, Ontario Tel: +1 905 670 02 20 Fax: +1 905 670 48 79

MEXICOESAB Mexico S.A. Monterrey Tel: +52 8 350 5959 Fax: +52 8 350 7554

USAESAB Welding & Cutting Products Florence, SC Tel: +1 843 669 44 11 Fax: +1 843 664 57 48

Asia/PacificCHINAShanghai ESAB A/PShanghaiTel: +86 21 2326 3000Fax: +86 21 6566 6622

INDIAESAB India Ltd CalcuttaTel: +91 33 478 45 17 Fax: +91 33 468 18 80

INDONESIAP.T. ESABindo Pratama Jakarta Tel: +62 21 460 0188 Fax: +62 21 461 2929

JAPANESAB JapanTokyoTel: +81 45 670 7073Fax: +81 45 670 7001

MALAYSIAESAB (Malaysia) Snd Bhd USJTel: +603 8023 7835Fax: +603 8023 0225

SINGAPOREESAB Asia/Pacific Pte LtdSingapore Tel: +65 6861 43 22 Fax: +65 6861 31 95

SOUTH KOREAESAB SeAH Corporation Kyungnam Tel: +82 55 269 8170Fax: +82 55 289 8864

UNITED ARAB EMIRATESESAB Middle East FZEDubai Tel: +971 4 887 21 11Fax: +971 4 887 22 63

Representative officesBULGARIAESAB Representative OfficeSofiaTel/Fax: +359 2 974 42 88

EGYPTESAB Egypt Dokki−CairoTel: +20 2 390 96 69 Fax: +20 2 393 32 13

ROMANIAESAB Representative Office BucharestTel/Fax: +40 1 322 36 74

RUSSIALLC ESABMoscowTel: +7 095 543 9281 Fax: +7 095 543 9280

LLC ESABSt PetersburgTel: +7 812 336 7080Fax: +7 812 336 7060

DistributorsFor addresses and phonenumbers to our distributors inother countries, please visit ourhome page

www.esab.com

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