esab ltn 255 aristo-tig 255
TRANSCRIPT
0740 800 116 Valid for serial no. 745--xxx--xxxx to 011--xxx--xxxx040820
LTN 255Aristotig 255
Service manual
-- 2 --conte
LIST OF CONTENTS Page
READ THIS FIRST 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .COMPONENT DESCRIPTION 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CONNECTION DIAGRAM 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .AP01 DESCRIPTION OF OPERATION 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Power supply 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Power supply monitoring 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Start / Stop input 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Remote control input 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Shunt input with amplifier AP10 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Arc voltage monitoring 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 HF generator 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Gas valve 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Machine type indicator 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Thermal overload cutout 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Welding process control 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hot start MMA 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 Control panel interface circuits 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 Pulse width modulator 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Gate circuit 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking the gate pulses 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Component positions, circuit board AP01 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TRANSISTOR BOARD AP02 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .TRANSISTOR BOARD AP03 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MOS TESTER 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SOFT STARTING 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CONTROL PANEL AP05 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DISPLAY BOARD AP06 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .AP07 SUPPRESSION BOARD 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SUPPRESSION BOARD AP08 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SUPPRESSION BOARD AP09 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FAULT CODES 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DISASSEMBLY / REASSEMBLY 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fitting the diode modules 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Removal of transistor circuit boards AP02 and AP03 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Refitting the transistor circuit board 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fitting the main transformer TC02 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TECHNICAL DATA 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .LOAD CHARACTERISTICS 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAINTENANCE 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .INSTRUCTIONS 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .INTRODUCTION 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .INSTALLATION 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .OPERATION 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Control panel 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Other functions 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPARE PARTS 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .NOTES 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rights reserved to alter specifications without notice.
-- 3 --cltn1de1
READ THIS FIRST
Maintenance and repair work should be performed by an experienced person, and electricalwork 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 circuitboard is divided into numbered blocks, which are described individually in more detail inthe description of operation. All component names in the wiring diagram are listed in thecomponent description.
This manual contains details of all design changes that have been made up to and includingAugust 2004.
The LTN 255 is designed and tested in accordance with international and Europeanstandard IEC/EN 60974--1 and EN 50199.On completion of service or repair work, it is the responsibility of the person(s) etc.performing the work to ensure that the product does not depart from the requirementsof the above standard.
WARNING
READ AND UNDERSTAND THE INSTRUCTION MANUAL BEFORE INSTALLING OR OPERATING.
ARC WELDING AND CUTTING CAN BE INJURIOUS TO YOURSELF AND OTHERS. TAKE PRECAU-TIONS WHEN WELDING. ASK FOR YOUR EMPLOYER’S SAFETY PRACTICES WHICH SHOULD BEBASED ON MANUFACTURERS’ HAZARD DATA.
ELECTRIC SHOCK -- Can killS Install and earth the welding unit in accordance with applicable standards.S Do not touch live electrical parts or electrodes with bare skin, wet gloves or wet clothing.S Insulate yourself from earth and the workpiece.S Ensure your working stance is safe.FUMES AND GASES -- Can be dangerous to healthS Keep your head out of the fumes.S Use ventilation, extraction at the arc, or both, to keep fumes and gases from your breathing zone and
the general area.ARC RAYS -- Can injure eyes and burn skin.S Protect your eyes and body. Use the correct welding screen and filter lens and wear protective
clothing.S Protect bystanders with suitable screens or curtains.
FIRE HAZARDS Sparks (spatter) can cause fire. Make sure therefore that there are no inflammable materials nearby.NOISE -- Excessive noise can damage hearingS Protect your ears. Use ear defenders or other hearing protection.S Warn bystanders of the risk.MALFUNCTION -- Call for expert assistance in the event of malfunction.
PROTECT YOURSELF AND OTHERS!
-- 4 --cltn1de1
-- 5 --cltn1de1
COMPONENT DESCRIPTION
This component description refers to the wiring diagram on page 8.
The LTN 255 is a primary--switched power unit, using parallel--connected MOSFET--transis-tors as the switching elements. The switching frequency is 48.5 kHz. The conductinginterval varies between zero and 9.5µs, depending on the welding current output. Theconducting time and frequency are controlled by circuit board AP01.
WARNING !STATIC ELECTRICITY can damage circuitboards and electronic components.S Observe precautions for handling electrostatic
sensitive devices.
S Use proper static--proof bags and boxes.ESD
AP01 The main circuit board with control electronics. See description on page 10.
AP02 Circuit board with power transistors for the positive pole,see description on page 22.WARNING! the transistors are connected to mains voltage potential.
AP03 Circuit board with power transistors for the negative pole,see description on page 24.WARNING! the transistors are connected to mains voltage potential.
AP05 Circuit board control panel. The circuit diagram is shown on page 28.
AP06 Display driver board with pulse generator. The circuit diagram is shown onpage 30.
AP07 Interference suppression circuit board: see the circuit diagram on page 31.
AP08 Interference suppression circuit board. Prevents mains--borne interference.The circuit diagram is shown on page 32.
AP09 Interference suppression circuit board, remote control connector, see thediagram on page 33.
AP10 Circuit board shunt amplifier, see description on page 13.
AP11 HF generator.
C01 Capacitor, 0.1µF, 1000V DC, transient protection.
C02, C03 Capacitors, 1000µF, buffer/smoothing capacitors.Time to discharge after turning off the unit: about two minutes.
C04 Decoupling capacitor, 0.1µF, 1000V DC, protects against HF.
C05 2 -- capacitors, 4.7µF, see L02.
-- 6 --cltn1de1
C06 -- C09 Capacitor, 0.1µF, 400V DC.
C10, C11 Capacitors, 1nF. Protection against transient voltages.
C13 -- C15 Capacitors, 10nF. Protection against transient voltages. The capacitors areonly used together with an old version of circuit board AP08, see page 32.
EV01 Fan, 24V DC, cooling the power components.
EV02 Fan, 24V DC, cooling AP11 and TV01.
HL01 Lamp, 28V, white, lights when mains power is on.
L01 Secondary inductor.
L02 Inductor, forms an LC circuit with C05 and V06 to reduce the risk of arcextinction at low welding currents.When V03 conducts, the LC circuit charges up. The circuit is capable oftemporarily maintaining a high arc voltage at low current, thus reducing therisk of arc extinction.Diode V06 prevents capacitor C05 from going negative.
L03 Ferrite ring core, transient protection.
L04 Ferrite ring core, transient protection.
L05 Ferrite ring core, transient protection.
QF01 Mains power supply switch, 3--pole.
R01 Resistor, 3.9kΩ 5W.
R02 Resistor, 8.2kΩ 5W.
RS01 Shunt, 119mV±1mV at 250A
ST01 Thermal overload cutout, for overload protection, mounted on the weldinginductor winding (L01). Breaks at 130 _C and resets at 100 _C
TC01 Control power transformer. The primary is supplied at 400V, withsecondary output voltages of 9, 20, 26 and 42V.Fuses are mounted on the control transformer. A number of machinesproduced before week 719 have no fuses. There is no need to fit fuses tothose machines.
TC02 Main transformer. For fitting instructions, see page 38.
TV01 HF transformer.
V01, V02 Mains rectifier bridges, 35A, 1200V. After replacing the rectifier bridges,the machine must be soft--started: see instructions on page 27.
-- 7 --cltn1de1
V03, V04 Rectifier and freewheel diodes.V03 rectifies the welding current.During the time interval between two voltage pulses from transformerTC02, the freewheel diodes V04 maintain the welding current from inductorL01.On the cooling fins three diode modules are mounted. Each diode moduleconsists of two diodes. If one module is broken all modules have to bereplaced.
From serial number 011--148--xxxx a new diode module is used. The ratedcurrent for the new module, SCOMES MKK300.4, is 300 A. The ratedcurrent for the old module, Motorola MURP20040CT, is 200 A. Because ofthe higher rating only two modules are needed for the rectifier unit. Theordering no. for the new module is the same as for the old.
For installation instructions, see page 36.
V05 LED, yellow. Lights when thermal cutout ST01 operates (breaks) as aresult of high temperature.
V06 Diode, see L02.
X01 -- X03 Terminal block.
XP01 Pin connector with jumper. Connected when the machine is used withoutwater cooler.
XS . . Sleeve connectors.
XS04 26--pole ribbon cable connector.
XS10 12--pole Burndy contact, for connection of remote control unit.
XS11 TIG central connector: only LTN 255 variant --894.
XS12 2--pole Cannon connector, only LTN 255 variant --895.
XS13 Welding current connector, OKC, only LTN 255 variant --895.
XS14 Welding current terminals, (two), OKC type.
XS20 26--pole connector for ribbon cable.
XS24 Connection for 400V to water cooler. (The water cooler is an accessory,which is mounted under the machine.)
XS25 Connection for water flow guard.
YV01 Solenoid valve.
-- 8 --cltn1de1
WIRING DIAGRAM
-- 9 --cltn1de1
1 POWER SUPPLY 8 GAS VALVE
2 POWER SUPPLY MONITORING 9 MACHINE TYPE SELECTION
3 START/STOP INPUT 10 THERMAL OVERLOAD SWITCH
4 REMOTE CONTROL INPUT 11 WELDING PROCESS CONTROL
5 SHUNT INPUT WITH AMPLIFIER AP10 12 INTERFACE CIRCUITS FOR CONTROL PANEL
6 ARC VOLTAGE SENSING 13 PULSE WIDTH MODULATOR
7 HF UNIT 14 GATE CIRCUIT
-- 10 --cltn1de2
AP01 DESCRIPTION OF OPERATION
This description refers to the wiring diagram on page 8 and to the components positiondiagram on page 21.Only those parts connected to the board’s inputs and outputs are described here. If the circuitboard is faulty, it must be replaced.After replacing the circuit board, the machine must be soft--started. See the instructionson page 27.
1 Power supply
The power supply to the board can be divided into three parts; a, b and c.
cltn0e06
The supply voltage from transformer TC01 is rectified and voltage regulator VR2stabilises the supply to +5¦0.25V DC.
Resistors R126 and R127, capacitor C104 and diode D27 form a voltage monitoringcircuit for the unregulated supply to voltage regulator VR2.The voltage from potential divider R126/R127 is connected to pin 9 of IC7: see 2)below. The voltage is about 2.5V.
Voltage regulator VR4 supplies the fans EV01 and EV02 with +28V.
Voltage regulator VR3 produces a stabilised +15V supply, which is used to supplythe remote control unit. This supply is referred to as +15VB, and its neutral point,0VB, is separated from the electronic neutral (0V). Potentiometer R122 is used toadjust the voltage. See also 4) on page 12.
cltn0e09
-- 11 --cltn1de2
Voltage regulator VR1 produces an output voltage of +20¦1.0V, which supplies thepulse width modulator output stage (Block 13).
Potential divider R100/R101 supplies 2.6V to the processor in Block 11. Thisprovides a signal that the power supply is available.
The +27V unregulated DC power supply to VR1 also supplies relay RE1 in Block 7and indicating lamp HL01 via resistor R120.
Zener diode D22 drops the voltage to +15V, and this, together with the --15V supply,powers the analogue circuits. The processor monitors the --15V supply by a signalfrom resistor R54.
2 Power supply monitoring
IC7 and IC9 monitor the voltage of batteryBA1. The nominal battery voltage is 3V. Ifit falls below 2.5V, the display shows errormessage E06. Battery life is about fiveyears.
The machine also operates without battery,but data stored in the welding data memory,see page 46, disappears when the mainsvoltage is switched off. At power up defaultvalues will be read into the memory.
A voltage of about 2.5V is supplied to IC7, pin 9, from power supply circuit 1a.If this voltage drops below the threshold voltage of 1.3V, pin 10 of IC7 goes low,providing the processor with a low power supply voltage signal. The processor thengenerates a ” ” warning signal in the display and stores current data.
If the +5V supply to pin 3 of IC7 drops below 4.65V, pin 15 goes low and inhibitsthe pulse width modulator in block 13. The processor receives a reset signal anddata in the RAM memory is protected by the backup battery power supply.
Pin 2 of IC7 supplies the RAM memory in Block 11 with power, both when themachine is energised and when it is shut down.
When power to the machine is turned off, the display also shows ” ” toconfirm that the processor has stored the current data.
-- 12 --cltn1de2
3 Start / Stop input
cltn0e10
The output signal from IC14, pin 4, goes high (+5V) when the torch contact switchis not activated, and low (0V) when it is activated.
4 Remote control input
cltn0e11
If the remote control input is activated, but there is no reference signal, resistor R72holds the reference input low. This results in a welding current of 3A for TIGwelding and 4A for MMA welding.
The remote control unit plug must incorporate a link between pins L and M. Whenthe remote control unit is connected, the voltage at the cathode of diode D19 is 0V.With the remote control unit removed, the voltage at the cathode of the diode is +5V.
When adjusting the +15VB voltage, link connections C3 and C4 and measure thevoltage at the cathode of diode D12. The voltage there must be 5.1¦0.05V. Adjustthe voltage by means of resistor R122: see circuit diagram 1b on page 10.
-- 13 --cltn1de2
5 Shunt input with amplifier AP10
Shunt amplifier circuit board AP10 is supplied with¦15V via connections D1 andD3 on circuit board AP01. At no--load voltage, the circuit board’s neutral voltage(0V) is at the same potential as the welding circuit negative connection.
250A welding current produces 119mV±1mV at the shunt. The signal from theshunt is amplified by the shunt amplifier, so that a 119 mV input signal from theshunt produces a 6.66V output signal. Resistors R10, R6 and R7 on circuit boardAP01 divide this voltage to 2.65V, which is then supplied to pin 3 of IC2.
IC2 is a buffer circuit. The processor receives a signal representing the weldingcurrent from output pin 6 of IC2. Resistor R4 connects the shunt signal to thecontrol amplifier.
LTN 255 has different current setting resolutions in the TIG and MMA modes. Inthe TIG mode, the welding current can be set in 1A steps, while in the MMA mode,the current can be set in 2A steps. This means that the lowest current in the MMAmode is 4A, while in the TIG mode it is 3A.
cltn0e28
Component positions, AP10
-- 14 --cltn1de2
6 Arc voltage monitoring
cltn0e13
This circuit measures and scales the arc voltage to a suitable level for the processor.64V arc voltage produces a voltage signal of 5.1V at the cathode of diode D3.
Open--circuit voltage controlThe arc voltage is connected to input D2 and supplied to potential divider R29 andR30, the output from which is supplied to the voltage control circuit. Theopen--circuit voltage must be about 70V.
7 HF generator
WARNING: Dangerous voltages in this circuit.
When the welding torch switch is operated, and the open--circuit arc voltage is over50V, relay RE1 closes and turns on HF generator AP11. It remains activated for0.75 seconds. If the arc has not struck within this time, the relay drops off.
The voltage on the primary side of HF transformer TV01 is about 400 V, and thesecondary voltage is about 8 kV.
From serial number xxx--006--xxxx a new type of HF generator is used,0367 268 001. This generator produces about 500 V on the primary side of the HFtransformer and about 10 kV on the secondary side.
The new HF generator replaces the old type as spare part for older machines. Thecolour of the new type is grey, the old is black. The new has screw connections forthe connection cables and different hole pattern for the mounting.
When fitting the new generator to older machines: three new mounting holes for thegenerator must be drilled and the cable shoes must be removed from the connectioncables. Fit the generator with the connection terminal turned towards the base plate.
-- 15 --cltn1de2
8 Gas valve
cltn0e15
Operating the torch trigger switch causes semiconductor relay RE2 to conduct andenergise solenoid valve YV01. C82 and R111 form an HF filter.
9 Machine type indicator
As this circuit board is used in other machines, it is necessary for the processor toknow what type of machine it is controlling. A link is therefore provided connectorG to short out pull--up resistor R112. When it connects G1 -- G2 it indicates that themachine is an LTN 255.
10 Thermal overload cutout
The thermal overload switch, ST01, is normally closed, which means that input K2is at 10V. This voltage is dropped by the potential divider formed by resistors R31and R32 to 4.8V, and used as an input voltage to the processor.
LED V05 indicates excessive temperature. When the thermal overload cutoutoperates, the LED lights up.
If you connect a water cooler with water flow switch to the machine, removeconnector XP01 and connect the flow switch to XS25.
-- 16 --cltn1de2
11 Welding process control
The processor inputs are the set values of welding data and the arc voltage. Theprocessor also calculates a set value signal for welding current and supplies this tothe current control amplifier.
cltn0p09
The process regulator control principle
Hot start MMAIn the MMA normal welding mode, the welding current is briefly elevated at thestart of welding. The higher current setting is engaged for 150 milliseconds.The starting current is twice the normal welding current (i.e. twice the set value),subject to a maximum of 300A.
cltn0p11
Welding start, normal welding, MMA1. Contact between the electrode and the workpiece.2. Starting current for 150 ms.
In the MMA drop welding mode, the starting current is three times the set value, butthe duration is shorter at only 50 ms. The maximum starting currents are the same asfor normal welding.
cltn0p12
Welding start, drop welding, MMA1. Contact between the electrode and workpiece.2. Starting current for 50 ms.
-- 17 --cltn1de2
12 Control panel interface circuits
cltn0e20
All machine functions are controlled from the panel on the front of the machine.
The display window and the LEDs are driven by IC21 and connected by a ribboncable to board contact B, pins 3--18.
The pulse generator on the front panel is supplied at +5V via inputs B25 and B26.Pulses are supplied from the pulse generator to connections B23 and B24 with a 90_mutual phase displacement. The pulse generator does only supply pulses when it’sshaft is turned. Resistors R97 and R98 are pull--up resistors. IC11 squares up thepulse flanks.
The two red and the two green pushbuttons are connected to 0V.Pressing any of them pulls down the corresponding input (B19 -- B22) to 0V, and thesignal is filtered by an RC filter network formed by capacitors C72 -- C75 andresistors R93 -- R96 before being applied to the processor.
-- 18 --cltn1de2
13 Pulse width modulator
The pulse width modulator determines the frequency and pulse time of the MOSFETtransistors’ control pulses.
It is important that the frequency and maximum pulse time are within the specifiedtolerances, see instructions on next page.
IC5 controls the pulse frequency, the pulse time and inhibition of pulses.
Transistor Q12 supplies the pulse transformer’s primary winding. Diodes D17 andD18 are squelch diodes that protect Q12 against back--emf from the transformer.
Pulse width modulator and gate circuit
14 Gate circuit
The MOSFET transistors’ drive stage produces control pulses for the gate--source onthe power transistors. There is a separate output for each switch unit.
All gate circuits are galvanically isolated from other circuits on the board. Theinsulation voltage between the pulse width modulator and the gate circuits is 4 kV.WARNING! The gate circuits are at mains voltage.
The two gate circuits are identical, and so only one is described here.
When Q12 conducts, a voltage pulse is produced on the transformer’s secondarywinding. This pulse is conducted via D13, D14 and output E1 to the gate on theMOSFET transistors. The pulse returns via the source, connection E2, D16 andC36. The mean peak gate -- source voltage is 12--15V.
The gate pulse between E1 and E2 charges C36 to 5.6V. When Q12 turns off, thevoltage from the secondary of the pulse transformer changes polarity, causing Q14and Q13 to start to conduct. The gate voltage becomes negative, turning off theMOSFET transistors.
-- 19 --cltn1de2
Checking the gate pulses
If circuit board AP02 or AP03 has failed, the gate pulses must always be checked.
Remove connections XS06 and XS07 (gate pulses). Connect a dummy gate load tooutputs E1 and E2 and to F1 and F2.
Dummy gate load
A set of different gate loads can be ordered from ESAB.The part number is 0468 469 003. The gate loads can be used to the followingmachines: LUC, LHL 130/160, LHL 250/315, LTL 160, LTL315, LUB 315,LHN, LTN, LTR, LTO, MechTig 315 and Protig 315.
IMPORTANT: never check the gate pulses when AP02 and AP03 areconnected: use a dummy gate load.
The gate pulse minimum level must be --3.5 to --5.5V, and the average maximumlevel 12 to 15V. Frequency must be 48.5 kHz ±0.5 kHz. Check that the maximumpulse time, measured at a voltage level of +5V, is 43 ±1% of the cycle time.
IMPORTANT: The frequency and pulse time are very important parameters.If they are incorrect, they can result in transistor failure in the main circuit.
If the gate pulse does not lie within these tolerances, replace circuit board AP01.
After replacing AP01, check the gate pulses again and soft--start the machine, asdescribed on page 27.
Gate pulses as measured across a dummy gate load on circuit board AP01
-- 20 --cltn1de2
cltn0e05
11
11
11
11
11
26
Component positions, circuit board AP01
-- 21 --cltn1de2
WARNING:High voltage withinthe shaded area.
Terminals X1 to X6 are tied to0V on the circuit board, andmust have good electrical con-tact with the screen enclosure.
-- 22 --cltn1de3
TRANSISTOR BOARD AP02
Circuit diagram circuit board AP02 (transistor board positive)
Individual transistors must not be replaced: if the circuit board is faulty, it must be replacedin its entirety. In addition, circuit board AP03 must also be replaced.Instructions on removing and fitting the circuit board are to be found on page 37.
A01, A02 Connections A01 -- A02 are for the gate pulses from circuit board AP01.
D1 -- D3 Transient voltage protection.
D5 Back--emf protection diode (squelch diode) for main transformer TC02when the transistors turn off.
D6 See R21.
F1 Fuse, for protection of circuit board AP01 if circuit board AP02 fails.
R21 R21, C3, C4 and D6 are limiting the peak voltage at transistors Q1 -- Q8.
Q1 -- Q8 MOSFET transistors. These require a special instrument(see MOS TESTER on page 26) for testing.
Due to a change to transistors with higher current rating, transistor Q6might not be fitted to the board. Spare part boards may have 7 or 8transistors.
-- 23 --cltn1de3
Component positions, circuit board AP02
-- 24 --cltn1de3
TRANSISTOR BOARD AP03
Circuit diagram circuit board AP03 (transistor board negative)
Individual transistors must not be replaced: if the circuit board is faulty, it must be replacedin its entirety. In addition, circuit board AP02 must also be replaced.See on page 37 for instructions on removing and fitting the circuit board.
A01, A02 Connections A01 -- A02 are for the gate pulses from circuit board AP01.
B01, B02 When the machine is loaded, pulses from a trigger pulse winding on maintransformer TC02 are supplied to connections B01 and B02, for use asgate pulses in controlling thyristor TY1.
D1 -- D3 Transient voltage protection.
D5 Back--emf protection diode (squelch diode) for main transformer TC02when the transistors turn off.
D12 See R29.
Q1 -- Q8 MOSFET transistors. These require a special instrument(see MOS TESTER on page 26 for testing.
Due to a change to transistors with higher current rating, transistor Q8might not be fitted to the board. Spare part boards may have 7 or 8transistors.
-- 25 --cltn1de3
R21 Charging resistor, 12Ω, 10W, for buffer capacitors C02 and C03. Whenenergising the power unit, pulses from control circuit board AP01 aredelayed by 300 ms to allow the buffer capacitor to charge.
R26 Discharge resistor for buffer capacitor C03. Discharge time for thecapacitor, after turning off the mains power supply, is about two minutes.
R27 Discharge resistor for buffer capacitor C02. After turning off mainspower supply, discharge time for the capacitor is about two minutes.
R29 R29, C7, C8 and D12 are limiting the peak voltage at transistors Q1 -- Q8.
TY1 Thyristor for shunting charging resistor R21 when the machine is loaded.If TY1 did not conduct, resistor R21 would burn out when the unit is onload.
Component positions, circuit board AP02
-- 26 --cltn1de3
MOS TESTER
The MOS tester is a special instrument, and can be ordered only from ESAB.Order number: 0468 469 001
Connect the instrument as follows:
S Disconnect the power unit from the mains.
S Disconnect capacitor C02 and C03.
S Remove the gate connections from AP01.
S Connect the clip on the red wire of the instrument to the red wire (the gate wire) on thetransistor board.
S Connect the clip on the yellow wire of the instrument to the yellow wire (the source) onthe transistor board.
S Connect the black wire to the cooling fins (drain).
Testing:
S Press the pushbutton marked TEST.
S If the board is healthy, both the red and green LEDs should flash alternately, about once asecond.
S If the transistor board is short--circuited, the red LED will light continuously. (Note thatthe green LED may also flash, or be continuously lit.)
S If the transistor board is open--circuited, the green LED will be continuously lit. Checkthat there is good electrical contact between the clip of the black wire and the coolingfins.
IMPORTANT
Even if only one transistor board is indicated as faulty, both boardsmust be replaced.
Check the gate pulses from AP01 before commissioning the new transistor boards.See instruction on page 19.
After replacement of the boards, the machine must be soft--started.
-- 27 --cltn1de3
SOFT STARTING
S Remove and insulate wires 07 and 08 from rectifier bridge V01, also remove and insulatewire 09 to rectifier bridge V02: see the circuit diagram on page 8.
S Connect an external power supply, having a current limit of 1A, to the positive andnegative connections on V01.
S Adjust the power supply voltage to 30V.
S Power the remaining parts of the unit from the normal power supply.
S Measure the output voltage from the machine. This must be 5.5V ±1V.
S Measure the secondary voltage from transformer TC02. With a voltage of 30V acrossthe buffer capacitor, the waveform must appear as shown below.
Secondary voltage at TC02 for 30V across the buffer capacitors
S Measure the voltage with the oscilloscope probeconnected to A and the screen to B according tothe picture below.
Measuring points for the secondary voltage at TC02
Up to and including ser. no. 011--147--xxxx From serial no. 011--148--xxxx
-- 28 --cltn1de3
CONTROL PANEL AP05
cltn0e23
AP06
Circuit diagram control panel AP05
-- 29 --cltn1de3
cltn0e24
Component positions control panel AP05
-- 30 --cltn1de3
DISPLAY BOARD AP06
cltn0e21
AP05
AP07
Circuit diagram display board AP06
The pulse generator Sw0 is transmitting pulses only when it’s shaft is turned.
-- 31 --cltn1de3
cltn0e22
Component positions display board AP06
AP07 SUPPRESSION BOARD
cltn0e25
Circuit diagram and component positions, suppression board AP07
-- 32 --cltn1de3
SUPPRESSION BOARD AP08
cltn0e34
cltn0e35
Diagram and component positions for the old version (0486 356 880) of circuit board AP08
Most of the machines produced before October 1998 are deliverd with circuit board 0486 356880. As spare part for those machines we recommend circuit board 0486 577 880. The newcircuit board suppresses noise better than the old board. To fit the new board in oldermachines a new mounting hole must be drilled in the mounting plate.
-- 33 --cltn1de3
Diagram and component positions for the new version (0486 577 880) of circuit board AP08
SUPPRESSION BOARD AP09
cltn0e27 cltn0e29
Diagram and component positions for circuit board AP09
-- 34 --cltn1de3
FAULT CODES
If the integral fault monitoring system detects a fault, the display shows Exx, where xx is atwo--digit number identifying the fault.
Faults E01 -- E06 can be detected during the automatic self--test routine that is run when theunit is switched on. Other faults can be detected as and when they occur.
E01 Memory error in internal RAM (in the processor).If this code occurs, turn the machine off and then on again. If it persists, replacecircuit board AP01.
E02 Memory error in external RAM (outside the processor).If this code occurs, turn the machine off and then on again.If it persists, replace circuit board AP01.
E03 Memory error, program memory (EPROM).If this code occurs, turn the machine off and then on again. If it persists,replace circuit board AP01.
E04 Memory error, RAM memory contents test.Check that the battery voltage is at least 2.5V. If it less than this, replace the battery.If the voltage is correct, turn the machine off and then on again: if the fault persists,replace circuit board AP01.
E05 Memory error, variable values outside limits in battery--backed RAM.Perform the same checks as for error code E04.
E06 Battery voltage below 2.5V. Measure the battery voltage: if it is less than 2.5V,replace the battery. If the battery voltage is over 2.5V, replace circuit board AP01.This error code can be reset by pressing one of the arrow pushbuttons. This willhave no effect other than to clear the error code. The display will return next timethe machine is turned on, and can again be cleared by pressing one of the arrowpushbuttons.If the battery is not replaced before its voltage has fallen below 2.0V, error code E04or E05 will be displayed. These error codes cannot be cleared.
E10 Incorrect power supply voltage (should be 20V), tolerance¦1V.Use a voltmeter to verify this fault. Measure the voltage from transformer TC01.If the transformer output voltage is correct, but the 20V supply voltage is wrong,replace circuit board AP01.
E11 Incorrect power supply voltage (should be --15V), tolerance +2/--1V.Use a voltmeter to verify this fault. Measure the voltage from transformer TC01.If the transformer output voltage is correct, but the --15V supply voltage is wrong,replace circuit board AP01.
-- 35 --cltn1de3
E13 High temperature. The thermal cutout has operated and indicating lamp V05 lights.The machine has been overloaded. Check that the cooling fan is running, and thatthe air filter is not blocked.
E14 Current servo fault: excessive difference between the actual value and the set valueof welding current. The power electronics circuitry is not capable of maintainingthe welding current that the process regulator is demanding.Tolerances:¦5A in TIG mode and¦10A in MMA mode.This code may occur when welding with electrodes which needs a higher voltagethan the machine can produce. It can also occur if the arc length is too long.
cltn0p10
The process regulator control principle
The process regulator servo compares the actual value signal and the set valuesignal, as shown above. The set value signal is the current control signal from theprocess regulator. The actual value signal is provided by the shunt signal, suppliedto the processor analogue inputs. These two signals are put through low--pass filters,each with the same time constant, and are then compared with each other.The time constant is about two seconds.
This fault code is reset when the welding current returns to within the tolerancevalues, when welding is restarted or when the machine is turned off.It is also possible to reset the display by pressing any of the pushbuttons. Doing thishas no effect other than to reset the display.
This fault code can sometimes occur during abnormal welding conditions, e.g. as aresult of a failed start.
When starting and finishing welding, the current is briefly outside the tolerancelimits. However, the above--mentioned filtering prevents these brief excursionsfrom triggering the fault code display.
Too low a power supply voltage to the + 5V voltage regulator. The display brieflyshows this symbol when the machine is turned off. If the voltage drops below thepermissible value when the machine is in use, the display will show this symbolbriefly and the machine will then stop.See also POWER SUPPLY MONITORING on page 11.
The display shows this symbol if the machine’s program has crashed. This can becaused, for example, by extreme external interference.If this error code occurs, find and rectify the source of the interference, turn off themachine, wait five seconds, and start it again.
-- 36 --cltn1ae1
DISASSEMBLY / REASSEMBLY
Fitting the diode modules
1. Clean the contact surface of the heat sink with extremely fine abrasive paper.
2. Apply a thin film of contact oil (see item 453 and 553 in the spare parts list) to the
contact surfaces.
3. Fit the diode modules and tighten the screws A (M6) to a torque of 6 Nm. Tighten the
screws B (M4) to a torque of 1 Nm.
The screws C (1/4” 20UNC2B) are to be tightened to a torque of 6 Nm.
Before serial number 011--xxx--xxxx From serial number 011--xxx--xxxx
From serial number 011--148--xxxx
From serial number 011--148--xxxx a new diode module is used. The rated current for the newmodule, SCOMES MKK300.4, is 300 A. The rated current for the old module, MotorolaMURP20040CT, is 200 A. Because of the higher rating only two modules are needed for therectifier unit. The ordering no. for the new module is the same as for the old.
When replacing the diode modules in machines with serial number prior to 011--148--xxxx itis sufficient to use only two modules if the new type, SCOMES MKK300.4, is fitted.
The busbars with item numbers 433, 434, 436, 533 and 536, see the spare parts list, are notmore available. If they have to be replaced, fit the new type of diode modules and the busbarswith item no. 643.
-- 37 --cltn1ae1
Removal of transistor circuit boards AP02 and AP03
1. Remove all wires and busbars connected to the board.
2. Remove the springs that hold the board (2) in position by prising them off with ascrewdriver (1) between the cooling flange and the spring.
Removal/refitting of transistor circuit board
Refitting the transistor circuit board
1. When replacing the transistor circuit board, both boards must always be replaced andnew springs must be fitted.
2. Clean the contact surface (3) of the heat sink with extremely fine abrasive paper.
3. Apply a thin film of contact oil (see item 453 and 553 in the spare parts list) to thecontact surfaces.
4. Place the circuit board (2) on the cooling fins. Secure first one spring on each side of theboard by pressing the spring down with a screwdriver (4). Then secure the remainingsprings.NOTE: The springs must be fitted where there are components that are to be in contactwith the heath sink. Due to a change to transistors with higher current rating, there mightbe less transistors on the spare part board than on the original board.
5. When fitting cable lugs and busbars to the boards, it is important that the washers arefitted in the correct order. Start by placing the lug on the foil, and then fit a flat washer, aspring washer and finally the screw.
Connections to circuit board AP03
a Wire 045 to the connection between C02and C03
b Busbar connected to positive on C03
c Busbar connected to negative on C02
d Wire 013 from negative of rectifier V02
e Gate connection from circuit board AP01
f Connector XS17 from transformer TC02
-- 38 --cltn1ae1
Fitting the main transformer TC02
When replacing the main transformer, it is also necessary to replace the transformer core.This is because the core is bonded with adhesive, and cannot be disassembled.
Adhesive and tape are required when fitting a new transformer, in addition to the coil andcore. Part numbers for the requisite adhesive and tape are shown as Item 428 in the spareparts list.
1. Transfer wire 020 and connector XS17 to the new transformer. If the wire needs to bereplaced, it is important to use the correct type of insulation (Teflon)
clhn1p08
Fitting wire 020
2. Apply a layer of tape (t) to each of the three airgaps in the transformer core. Use the tapespecified in the spare parts list.
3. Apply Loctite 649 to the contact faces between the cores and between the core and coil.Secure the transformer in position in the machine. The adhesive takes about 20 minutesto harden.
cmha2p33
Airgap (t) in the transformer core
-- 39 --cltn1ae1
TECHNICAL DATA
Permitted load at:35% duty cycle, TIG35% duty cycle, MMA60% duty cycle100% duty cycle
250 A / 20 V250 A / 30 V180 A / 27 V140 A / 26 V
Setting range, TIG 3 -- 250 A
Setting range, MMA 4 -- 250 A
Slope up 0 -- 10 sec
Slope down 0 -- 10 sec
Gas pre--flow 0 -- 25 sec
Gas post--flow 0 -- 25 sec
Pulse time 0.02 -- 5.0 sec(0.001 -- 5.0 sec)
Pause time 0.02 -- 5.0 sec(0.001 -- 5.0 sec)
Open--circuit voltage 70 -- 80 V
Open circuit power 40 W
Active power at max current MMA 8.78 kW
Apparent power at max current MMA 13.3 kVA
Power factor at max current MMA 0.65
Efficiency at max current MMA 0.85
Mains connectionMains fuse, slow--blowMains cable, cross section
400 V 50--60 Hz16 A4 x 1.5mm2
Weight 25 kg
Dimensions l x w x h 515 x 285 x 415
Application class
Class of enclosure IP23
The welding power source comply with the requirements set out in IEC 974--1
Duty cycleThe duty cycle refers to the time in per cent of a ten--minute period that you can weld at acertain load without overloading the welding power source.
Enclosure classThe IP code indicates the enclosure class, i. e. the degree of protection against penetration bysolid objects or water. Equipment marked IP 23 is designed for indoor and outdoor use.
Application class
The symbol indicates that the power source is designed for use in areas where there is anincreased electrical hazard.
bt07d109
-- 40 --cltn1ae1
LOAD CHARACTERISTICS
MAINTENANCE
LTN 255 normally need only a minimum ofmaintenance. It is usually sufficient to blow itclean with compressed air once a year and toclean the fan air filter regularly.
If the machine is used in a dusty or dirtyenvironment, it should be blown clean more often.
Removing the filter
The machine’s memory is battery--backed. If the display shows the E06 error code, batteryvoltage is low. See Error Codes on page 34.
NOTE that all guarantee obligations will be void if the customer carries out any work on themachine during the guarantee period to rectify any faults.
-- 41 --cltn1de4
INSTRUCTIONS
This chapter is an extract from the instruction manual for the LTN 255.
INTRODUCTION
Note:This product is solely intended for arc welding.
LTN 255 is equipped with ARC PLUS, a new type of control that with MMA weldingprovides a more intensive, more concentrated and smoother arc. It reacts quicker after a shortcircuiting drop transfer, which reduces the risk of the electrode sticking.
In addition, the machine is equipped with Arc Force, which means that the power source’sdynamics can be adjusted, softer or harder depending on the type of electrode and thewelder’s preference.ARC PLUS -- because of the regulator’s good characteristics it is only necessary to changethe Arc Force settings in exceptional circumstances.
When drop welding using stainless steel electrodes a special feature on the machine can beactivated to facilitate welding.
LTN 255 is available in two designs, one with a central connector and one with an OKCconnector for a TIG torch. LTN 255 is supplied complete with a 5 metre mains cable, 5metre return cable, gas hose and hose clips. Machines with a central connector are also fittedwith a safety bar to protect the connectors from impact.
As an accessory there is a loop handle to fit on the machines which acts as a cable reel as wellprotecting the control panel. There are also two carriages available for transportation with agas cylinder and cooling unit.
-- 42 --cltn1de4
INSTALLATION
WARNINGThis product is intended for industrial use. In a domestic environment it may causeradio interference. It is the user’s responsibility to take adequate precautions.
Mains voltage 400 V ¦10 %, 3--phase
Mains frequency 50 -- 60 Hz
Fuse, slow rupture 16 A
Mains cable, cross section 4x1.5 mm2
Welding cable, cross section 35 mm2
LTN 255 is equipped with mains voltage compensation, which means that a¦10% variationin the mains voltage only results in a¦0.2% variation in the welding current.
To reduce the voltage drop when using a long cable it can be advisable to select a heaviercable cross section.
1. Place the equipment in a suitable place and make sure the rectifier is not covered orset--up so that cooling is prevented.
2. Make sure the machine is connected to the correct mains voltage.Earth according to applicable directives.
3. Connect the shielding gas.
4. Connect the TIG torch and the return cable or the MMA welding cables.
The machine is now ready for welding.
-- 43 --cltn1de4
OPERATION
84 5 3 2
1
9
610 11 12 7
1. Mains power switch 9. Gas nipple (connection of gas cylinder)
2. Yellow LED, indicating overtemperature 10. Connection for TIG torch
3. White indicating lamp 12. Connection for return cable when TIGldi4. Display welding
5. Setting knob The welding cable and return cable shouldb d 11 d 12 h ldi i h6. Push--buttons be connected to 11 and 12 when welding withcoated electrodes
7. Remote control connectioncoated electrodes
8. Dust filter
When the main power switch is switched on the white indicating lamp, on the front, is lit.
To take your mind off the risk of overloading the machine it has been equipped with anintegrated thermostat that trips if the temperature becomes too high.When this occurs the welding current is cut out and the yellow indicating lamp comes on. Inaddition, the error code ”E13” is displayed. When the temperature has dropped the thermostatautomatically resets.
-- 44 --cltn1de4
Control panel
On the front of the machine there is a control panel for the selection of functions and settingof parameters. This consists of a display, setting knob, LEDs and push--buttons.By using the push--buttons you can move between the different functions. The selectedfunction is indicated by respective LEDs coming on.
One line at a time is set. The current line is indicated by a red LED. Movement between linestakes place using the red arrow keys.Movement within each line takes place using the green arrow keys.
All settings are made using the setting knob. The LEDs to the right of the display indicate theactual unit (ampere/volt/seconds). On the lines where only a function is selected, ”------” isshown on the display.
Description of the functions:
S Line 1S Line 2S Line 3S Line 4
S Line 5
S Line 6S Line 7
Line 1 TIG welding or MMA weldingIf MMA welding is chosen, the current is set here and lines 2--5 are ignored.
bt07d002
-- 45 --cltn1de4
Line 2 TIG/HF ignition or TIG/Liftarc ignition
If HF ignition has been selected, the HF generator will be activated when the torchtrigger switch is operated. The HF generator is activated for 0.75 seconds: if the archas not struck during this time, the machine turns off the HF generator.
Operate the LIFTARC ignition feature as shown below.
bt07t00
Place the electrode against the workpiece . Press the torch switch
bt07t002
Tilt the torch a little, lift and an arc is produced To stop -- release the torch trigger
Line 3 Continuous current or pulsed current O O -- O
Line 4 2 stroke or 4 stroke trigger action2 stroke trigger action means that the arc is ignited when the torch trigger ispressed in and is extinguished when the trigger is released.4 stroke trigger action means that when the torch trigger is pressed in ”1” themachine starts with the pilot current and then slopes up to the set currentwhen the trigger is released ”2”. When the trigger is pressed in again ”3” themachine slopes down to the pilot current. The arc is extinguished when thetrigger is released ”4”.
bt07d003
-- 46 --cltn1de4
Line 5 Parameter setting
1. Gas pre flow 0--25 s2. Slope up 0--10 s3. Pulse current or continuous current 3--250 A4. Pulse time 0.02--5.0 s (0.001--5.0 s)5. Pause current 3--250 A6. Pause time 0.02--5.0 s (0.001--5.0 s)7. Slope down 0--10 s8. Gas post flow 0--25 s
Line 6 Measurement instrumentShows the welding current or arc voltage during the present welding run.The measurement instrument has a hold function that locks the measurementvalue when the welding run is stopped.
Line 7 Welding data memory O O 1 O 2 O1--2 O AFour different sets of welding data settings can be stored in the machine’smemory, two for TIG mode and two for MMA mode.
The following can be stored:TIG: selected option from line 3 (continuous or pulsed current) All settingson line 5.
MMA: Welding current
The welding data memory is changed using the green arrowkeys.Changes can also be made by quickly pressing the torch trigger, regardless ofwhether you are welding or not.To activate the possibility of jumping between programs both the greenarrow keys should be pressed simultaneously.
When the jump function is activated an indicating lamp comes on. O 1--2If the 4 stroke trigger action is selected, quickly pressing the trigger willswitch the welding data. The same thing applies in 2 stroke trigger action ifyou are not welding. During welding, using 2 stroke trigger action, yourelease the trigger momentarily to change the welding data.Aristotig has battery backup so that the settings remain in memory evenwhen the machine is switched of or disconnected from the power supply.
-- 47 --cltn1de4
Other functions
Drop welding (MMA)Drop welding can be used when welding with stainless steel electrodes.The technique involves the arc switching between igniting and extinguishing to allow bettercontrol over the heat transfer. The electrode only needs to be lifted a little for the arc to beextinguished.The machine should be in the current setting mode when the function is activated. Press bothof the green arrow keys simultaneously for 2 seconds and the symbol ”--_--” indicatesthat the function is activated.This mode remains active even if the machine is switched off. The machine is reset fornormal welding again using the same method and ”------” is then indicated on the display.
Arc Force (MMA)The Arc Force setting changes the machine’s dynamic. A softer or harder arc can be obtained.The machine should be in the current setting mode when activating the function by pressingthe two red arrow keys simultaneously for 2 seconds. The display shows a valuebetween 0 and 100. The higher the value the harder the arc.Press one of the buttons and the power source returns to the normal operating mode. The setArc Force value remains. Different Arc Force settings can be stored in the machine’s two setsof welding data memory.
Pulse time/Pause time (TIG)Normally the setting range for these parameters is 0.02--5.0 s. Through pressing the two greenarrows simultaneously for 2 seconds, times down to 0.001 s can be set. This extended settingrange remains until the machine is reset using the same method. When activating the functionthe machine should be in the mode for setting the pulse time/pause time. Note that timesbelow 0.250 s are displayed without the decimal point.
Remote controlUsing the remote control socket on the machine the current can be remotely regulated in TIGand MMA modes.If pulsed current is selected in TIG mode, it is the pulsed current that is remotely regulated.The set value from the remote control is shown on the display by stepping to the positionwhere the current should be set when not using the remote control.Switching to the remote mode takes place automatically when the unit is connected.This is confirmed by the LED coming on. O A
(NOTE! the pins L and M in the remote control’s connecting plug must be strapped forautomatic connection to take place).
The following remote controls can be connected:PHA1, PHA2, PHA5, PHB1, PHB2, PHC2 and FS002.
NOTE: When using FS002 the slope--up and slope--down times should be set to 0 seconds.
SPARE PARTS
The spare parts list for the LTN 255 is published in a separate document with filename /ordering no. 0457 328 990
-- 48 --notes
NOTES
-- 49 --notes
ESAB ABSE--695 81 LAXÅSWEDENPhone +46 584 81 000
www.esab.com
031021
ESAB subsidiaries and representative offices
EuropeAUSTRIAESAB Ges.m.b.HVienna--LiesingTel: +43 1 888 25 11Fax: +43 1 888 25 11 85
BELGIUMS.A. ESAB N.V.BrusselsTel: +32 2 745 11 00Fax: +32 2 726 80 05
THE CZECH REPUBLICESAB VAMBERK s.r.o.PragueTel: +420 2 819 40 885Fax: +420 2 819 40 120
DENMARKAktieselskabet ESABCopenhagen--ValbyTel: +45 36 30 01 11Fax: +45 36 30 40 03
FINLANDESAB OyHelsinkiTel: +358 9 547 761Fax: +358 9 547 77 71
FRANCEESAB France S.A.Cergy PontoiseTel: +33 1 30 75 55 00Fax: +33 1 30 75 55 24
GERMANYESAB GmbHSolingenTel: +49 212 298 0Fax: +49 212 298 204
GREAT BRITAINESAB Group (UK) LtdWaltham CrossTel: +44 1992 76 85 15Fax: +44 1992 71 58 03
ESAB Automation LtdAndoverTel: +44 1264 33 22 33Fax: +44 1264 33 20 74
HUNGARYESAB KftBudapestTel: +36 1 20 44 182Fax: +36 1 20 44 186
ITALYESAB Saldatura S.p.A.Mesero (Mi)Tel: +39 02 97 96 81Fax: +39 02 97 28 91 81
THE NETHERLANDSESAB Nederland B.V.UtrechtTel: +31 30 248 59 22Fax: +31 30 248 52 60
NORWAYAS ESABLarvikTel: +47 33 12 10 00Fax: +47 33 11 52 03
POLANDESAB Sp.z.o.oWarszawTel: +48 22 813 99 63Fax: +48 22 813 98 81
PORTUGALESAB LdaLisbonTel: +351 1 837 1527Fax: +351 1 859 1277
SLOVAKIAESAB Slovakia s.r.o.BratislavaTel: +421 7 44 88 24 26Fax: +421 7 44 88 87 41
SPAINESAB Ibérica S.A.Alcobendas (Madrid)Tel: +34 91 623 11 00Fax: +34 91 661 51 83
SWEDENESAB Sverige ABGothenburgTel: +46 31 50 95 00Fax: +46 31 50 92 22
ESAB International ABGothenburgTel: +46 31 50 90 00Fax: +46 31 50 93 60
SWITZERLANDESAB AGDietikonTel: +41 1 741 25 25Fax: +41 1 740 30 55
North and South AmericaARGENTINACONARCOBuenos AiresTel: +54 11 4 753 4039Fax: +54 11 4 753 6313
BRAZILESAB S.A.Contagem--MGTel: +55 31 3369 4333Fax: +55 31 3369 4440
CANADAESAB Group Canada Inc.Missisauga, OntarioTel: +1 905 670 02 20Fax: +1 905 670 48 79
MEXICOESAB Mexico S.A.MonterreyTel: +52 8 350 5959Fax: +52 8 350 7554
USAESAB Welding & Cutting ProductsFlorence, SCTel: +1 843 669 44 11Fax: +1 843 664 44 58
Asia/PacificCHINAShanghai ESAB A/PShanghaiTel: +86 21 6539 7124Fax: +86 21 6543 6622
INDIAESAB India LtdCalcuttaTel: +91 33 478 45 17Fax: +91 33 468 18 80
INDONESIAP.T. Esabindo PratamaJakartaTel: +62 21 460 01 88Fax: +62 21 461 29 29
MALAYSIAESAB (Malaysia) Snd BhdSelangorTel: +60 3 703 36 15Fax: +60 3 703 35 52
SINGAPOREESAB Singapore Pte LtdSingaporeTel: +65 861 43 22Fax: +65 861 31 95
ESAB Asia/Pacific Pte LtdSingaporeTel: +65 861 74 42Fax: +65 863 08 39
SOUTH KOREAESAB SeAH CorporationKyung--NamTel: +82 551 289 81 11Fax: +82 551 289 88 63
UNITED ARAB EMIRATESESAB Middle EastDubaiTel: +971 4 338 88 29Fax: +971 4 338 87 29
Representative officesBULGARIAESAB Representative OfficeSofiaTel/Fax: +359 2 974 42 88
EGYPTESAB EgyptDokki--CairoTel: +20 2 390 96 69Fax: +20 2 393 32 13
ROMANIAESAB Representative OfficeBucharestTel/Fax: +40 1 322 36 74
RUSSIA--CISESAB Representative OfficeMoscowTel: +7 095 937 98 20Fax: +7 095 937 95 80
ESAB Representative OfficeSt PetersburgTel: +7 812 325 43 62Fax: +7 812 325 66 85
DistributorsFor addresses and phonenumbers to our distributors inother countries, please visit ourhome page
www.esab.com