ESAB LKA 180 User manual

0349 300 002 Valid for serial no. 618−xxx−xxxx040928
LKA 180/240
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Service manual

INTRODUCTION 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RATING PLATE 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COMPONENT DESCRIPTION, LKA 180/240 4. . . . . . . . . . . . . .
CONNECTION DIAGRAM, LKA 180 Single−phase, 230 V 5.
CONNECTION DIAGRAM, LKA 180 3−phase, 400 V 6. . . . .
CONNECTION DIAGRAM, LKA 180 3−phase, 230/400 V 7.
CONNECTION DIAGRAM, LKA 240 3−phase, 400 V 8. . . . .
CONNECTION DIAGRAM, LKA 240 3−phase, 230/400 V 9.
CIRCUIT DIAGRAM, CIRCUIT BOARD AP1 10. . . . . . . . . . . . . .
COMPONENT POSITIONS, CIRCUIT BOARD AP1 12. . . . . . . .
DESCRIPTION OF OPERATION, CIRCUIT BOARD AP1 13. . .
LOAD CHARACTERISTICS 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TECHNICAL DATA 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INSTALLATION 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OPERATION 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WELDING DATA SELECTION 21. . . . . . . . . . . . . . . . . . . . . . . . . . .
SPARE PARTS LIST LKA 180/240 24. . . . . . . . . . . . . . . . . . . . . .

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INTRODUCTION
This service manual is intended for use by technicians with electrical training when carrying
out fault tracing and repair of the equipment.
At the end of the manual, there is a brief guide to using the machine in order to assist in
understanding the machine.
The manual contains all design modifications introduced up to and including September
2004.
Use the diagrams in the manual when tracing faults. The machine components are described
in alphabetical order on the pages foregoing the connection diagram.
The LKA 180 and 240 are designed and tested in accordance with international
standard EN 60974−1, 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 requirements
of the above standard.
WARNING
READ AND UNDERSTAND THE OPERATING 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 BE
BASED ON MANUFACTURERS’ HAZARD DATA.
ELECTRIC SHOCK −Can kill
SInstall and earth the welding unit in accordance with applicable standards.
SDo not touch live electrical parts or electrodes with bare skin, wet gloves or wet clothing.
SInsulate yourself from earth and the workpiece.
SEnsure your working stance is safe.
FUMES AND GASES −Can be dangerous to health
SKeep your head out of the fumes.
SUse 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.
SProtect your eyes and body. Use the correct welding screen and filter lens and wear protective
clothing.
SProtect bystanders with suitable screens or curtains.
FIRE HAZARD
SSparks (spatter) can cause fire. Make sure therefore that there are no inflammable materials nearby.
MALFUNCTION −Call for expert assistance in the event of malfunction.
PROTECT YOURSELF AND OTHERS!
Rights reserved to alter specifications without notice.

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RATING PLATE
The rating plate is secured to the back of the machine. The example shown below is the rating
plate for an LKA 240 with an explanation of how the plate should be read and interpreted.
1. LKA 240 is the type designation for this power source. The first letter, L, indicates that
the LKA 240 is a rectifier, while K indicates Compact (Kompakt in Swedish) and A indi-
cates the design generation.
The 240 indicates the maximum welding current.
2. These symbols indicate that the LKA 240 incorporates a transformer and rectifier.
3. This section indicates the voltage/current characteristic when welding and a current range
of 30 -- 200 A.
The voltage values of 15 and 24 V in the heading indicate that we comply with the in-
ternational arc characteristic as defined in IEC 974--1.
X =The duty cycle, indicating for how long a time welding can be carried out at the
specified welding data, expressed as a percentage of a ten--minute period.
I2=The current at the respective duty factors.
U2=The arc line characteristic voltage.
Uo=The open--circuit voltage.

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4. Indicates that the unit is intended for connection to a 400 V three−phase supply at 50 or
60 Hz.
I1= primary currents at the various load points.
5. IP21 indicates the enclosure class in respect of protection against penetrating objects and
water. Enclosure class IP21 indicates that the equipment is intended for indoor use,
while IP23 equipment is also suitable for outdoor use.
The symbol indicates that the rectifier is designed for use in areas of elevated electri-
cal risk.
6. The machine’s serial number, in the form of three groups of figures (xxx yyy zzz).
The first group (xxx) indicates the version. The figures represent the year and week of
approval of the version.
The second group (yyy) shows the year and week of final testing of the machine. For
example, 341 indicates Week 41, 1993.
The final group (zzz) consists of three or four figures, and is a serial number in the range
0001 to 9999.
7. Shows that ESAB complies with the international standard, IEC 974−1.

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COMPONENT DESCRIPTION, LKA 180/240
The following component description refers to the connection diagrams on the following
pages.
AP1 Circuit board with control electronics: see the diagram on page 10 and
description on page 13.
C1−C3 Capacitor PME 0.1µF, 400 VDC, transient and HF protection.
EV1 Fan, 24 VDC, fitted in the LKA 240 and the single−phase version of the
LKA 180.
HL1 Lamp, 28 V, white, lights when the main switch is On.
KM1 Contactor, 42 V operating voltage.
L1 Inductor.
M1 Wire feed unit motor.
QF1 Switch, 7−way in the LKA 180 and 10−way in the LKA 240.
R1 Resistor, 1 Ω, only fitted in the single−phase version of LKA 180.
R2 Resistor, 5.6 kΩ5 W, only fitted in the single−phase version of LKA 180.
SB1 Welding torch trigger switch
ST1 Thermal overload cutout, for protection against overload, fitted in the winding of
main transformer TM1. The switch operates (opens) at a temperature of 120 _C.
ST2 Thermal overload cutout, for protection against overload, fitted on the diode
bridge cooling fins (V1 −V6). It operates (breaks) at 110 _C in the single−phase
version of the LKA 180 and at 130 _C in other machines.
TC1 Control power supply transformer.
Supplied at 230 or 400 V and protected by a 1.6 A anti−surge fuse.
Secondary output voltages of 42, 27 and 20 V to circuit board AP1.
TM1 Main transformer.
V1−V6 Diode bridge, rectifier.
V7 LED, yellow. Lights if thermal overload cutouts ST1 or ST2 operate as a result of
high temperature.
XS1 9−pole connector.
XS2 5−pole connector.
XS3 7−pole connector.
XS4 2−pole connector.
XT1 Mains terminal block, 5−way.
XT2 Terminal block, positive and negative welding voltages.
XT3 6−pole terminal block for mains voltage selection.
Fitted only in the multi−voltage versions of the machine.
YV1 Solenoid valve

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CONNECTION DIAGRAM, LKA 180 Single−phase, 230 V
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The first 150 machines
were delivered with
switch 0408/8112.
The part No. in the
spare parts list is
referring to the other
switch, which has to be
used as spare part for
all machines.

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CONNECTION DIAGRAM, LKA 180 3−phase, 400 V
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When checking the no−load
voltages, load the machine with
a dummy load of 5.6 kΩ5 W,
connecting it between plus and
minus on the rectifier bridge.

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CONNECTION DIAGRAM, LKA 180 3−phase, 230/400 V
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When checking the no−load
voltages, load the machine with
a dummy load of 5.6 kΩ5 W,
connecting it between plus and
minus on the rectifier bridge.

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CONNECTION DIAGRAM, LKA 240 3−phase, 400 V
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When checking the no−load
voltages, load the machine
with a dummy load of 5.6 kΩ5
W, connecting it between plus
and minus on the rectifier
bridge.

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CONNECTION DIAGRAM, LKA 240 3−phase, 230/400 V
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When checking the no−load
voltages, load the machine
with a dummy load of 5.6 kΩ
5 W, connecting it between
plus and minus on the
rectifier bridge.

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CIRCUIT DIAGRAM, CIRCUIT BOARD AP1

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COMPONENT POSITIONS, CIRCUIT BOARD AP1
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DESCRIPTION OF OPERATION, CIRCUIT BOARD AP1
This description relates to the circuit diagram on page 10 and to the component positions
diagram on page 12.
Only those items connected to the inputs and outputs of the board are described here. If the
board is faulty, it must be replaced.
1POWER SUPPLY
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Transformer TC1 supplies indicating lamp HL1 and rectifier bridge BR1
with 27 V AC. The unsmoothed DC output from BR1 is smoothed by capacitors C5 and C25
to produce an open−circuit voltage of 38 V ”10%.
This provides the power supply for the wire feeder motor.
Connections T6 and T7 supply 20 V AC from transformer TC1 to diodes D18 −D21.
The rectified voltage is about 24 V in the fan−cooled machines and somewhat higher in the
3−phase LKA 180. This supply powers fan EV1 in the fan−cooled machines.
Voltage regulator VR1 is supplied via diode D1 to provide a regulated 15 "0.6 V supply.
2REFERENCE CIRCUIT
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Potentiometer R49 controls the wire feed speed and is connected to terminals P1 −P3.
It is energised via resistors R51 −R55 and R23. The reference voltage is supplied through
resistor R20 to the error amplifier.

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START/STOP CIRCUIT, THERMAL OVERLOAD CIRCUIT AND SPOT
WELDING CIRCUIT
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3START AND STOP CIRCUIT
When the torch trigger switch SB1 is not activated, the voltage between M3 and M4 is
24 V. Pressing the trigger switch shorts the circuit, producing a voltage of 0 V
between M3 and M4.
4THERMAL OVERLOAD CIRCUIT
The machine contains two thermal overload cutouts, wired in series and connected to
inputs T8 and T9. If either of them operates, the torch trigger switch circuit cannot be
short−circuited, with the result that wire feed cannot be started.
When either of the thermal cutouts has operated, LED V7 is energised to indicate this
via diode D7.
5SPOT WELDING CIRCUIT
Potentiometer R50 controls the spot welding time and incorporates a switch. When in
the zero position, the switch is open.
When the switch in R50 and torch trigger switch SB1 are closed, capacitor C22
charges up through resistors R32 and R50. Wire feed stops when the voltage on C22
reaches 8.8 V. The trigger switch must be released and then pressed again before a
new spot weld can be made.
The spot welding time can be adjusted between 0.2 and 2.5 seconds "30%.

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6BURN−BACK TIME
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The burn−back time is the time from when wire feed ceases until contactor KM1
drops off.
During welding, the voltage at pin 13 of IC2 is low. The output of the inverter at pin
14 is therefore high, turning on transistor Q2 and activating relay RE1.
When the torch trigger switch is released, or when the spot welding time expires,
capacitor C23 charges up via resistors R36, R37 and R38. When the voltage across
C23 reaches 8.8 V, output 14 of IC2 goes low, turning off Q2 and causing relay RE1
to drop off.
Potentiometer R38 is used to adjust the burn−back time
between 15 and 250 milliseconds. As delivered, the
burn−back time is set to 170 milliseconds.
Adjusting the burn−back time
From machine number 618 ... .... R38 is not mounted, the burn−back time is not
adjustable and set to 33 milliseconds with the resistors R36 and R37.
Spare part circuit boards to machines with earlier machine numbers are also having a
none adjustable burn−back time, which is set to 65 milliseconds.
7CONTROL AMPLIFIER AND PULSE WIDTH MODULATOR
The control amplifier compares the set value speed signal with the actual speed and
supplies a control signal to the pulse width modulator. The actual value speed signal
is provided by measuring the motor voltage.
The pulse width modulator controls the frequency and pulse time of current to the
wire feed motor.
The switching frequency is about 2.5 kHz. The frequency is constant: it is the
mark/space ratio that is varied.

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MOTOR DRIVE AND BRAKING
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8MOTOR DRIVE CIRCUIT
The output stage of the pulse width modulator is connected to transistor Q1 via
resistor R16.
A motor current signal is provided by measuring the voltage across resistor R4,
connected to transistor Q1.
If the voltage across R4 exceeds 1.1 V "60 mV, the gate pulses to Q1 are inhibited.
This provides a current limit of about 11 A.
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Motor voltage when the wire feed speed control potentiometer is in its centre position. The motor is
unloaded.
9BRAKING CIRCUIT
When wire feed is to stop, the pulse width modulator turns off the pulses to Q1.
Transistors Q3 and Q4 turn on: transistor Q4 provides a path for dynamic braking
current to flow through resistor R47 and diode D17.

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LOAD CHARACTERISTICS
LKA 180 single phase
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LKA 180 3−phase
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LKA 240
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TECHNICAL DATA
LKA 180
230V
LKA 180
400V
LKA 180
230/400V
LKA 240
400V
LKA 240
230/400V
Permissible loading
At 10% duty cycle
At 15% duty cycle
At 60% duty cycle
At 100% duty cycle
180A/19V
75A/19V
60A/17V
180A/19V
75A/18V
60A/17V
180A/19V
65A/20V;75/18
60A/17V;60/17
240A/22V
110A/19V
85A/18V
240A/22V
120A/20V;110/19
85A/19V;85/18
No−load voltage 16−33V 15−33V 15−33V 18−36V 18−36V
Voltage steps 7 7 7 10 10
Wire feed speed 1−15 m/min 1−15 m/min 1−15 m/min 1−15 m/min 1−15 m/min
Spot welding time 0.25−2.5 s 0.25−2.5 s 0.25−2.5 s 0.25−2.5 s 0.25−2.5 s
Wire drum capacity 5−15 kg 5−15 kg 5−15 kg 5−15 kg 5−15 kg
Wire sizes
Non−alloyed steel
Stainless steel
Aluminium
Gasless filler wire
0.6−0.8 mm
0.6−0.8 mm
1.0 mm
0.8−0.9 mm
0.6−0.8 mm
0.6−0.8 mm
1.0 mm
0.8−0.9 mm
0.6−0.8 mm
0.6−0.8 mm
1.0 mm
0.8−0.9 mm
0.6−0.8 mm
0.6−0.8 mm
1.0 mm
0.8−0.9 mm
0.6−0.8 mm
0.6−0.8 mm
1.0 mm
0.8−0.9 mm
Power supply 230V 50Hz
1−phase
400V 50Hz
3−phase
230/400V 50Hz
3−phase
400V 50Hz
3−phase
230/400V 50Hz
3−phase
Maximum primary current 30A 9A 16/9A 11A 19/11A
Mains fuse rating 20A slow−blow 10A slow−blow 10/10A slow−blow 10A slow−blow 16/10A slow−blow
Mains cable, area 3x2.5 mm24x1.5 mm24x2.5 mm24x1.5 mm24x2.5 mm2
Weight 53 kg 53 kg 53 kg 56 kg 56 kg
Enclosure class IP21S IP21 IP21 IP21 IP21
Application class
The symbol indicates that the machine has been designed and built for use in areas of
elevated electrical risk.
IP21 indicates the enclosure class in respect of protection against penetrating objects and
water. Enclosure class IP21 indicates that the equipment is intended for indoor use, while
IP23 equipment is also suitable for outdoor use.
Main dimensions, LKA 180 and LKA 240
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