ESAB LKB 160 User manual

LKB160

WELDING RECTIFIER

Service manual

0349 300 018 00-10-05

1. CONNECTION DIAGRAM, LKB160, 230V ......................................................................................... 4

2. COMPONENT POSITIONS - CONTROL CIRCUIT BOARD LKC13C (A1) ...................................... 6

3. CONTROL CIRCUIT FUNCTION ........................................................................................................ 6

3.1 DESCRIPTION OF OPERATION-PCB LKC13C (STANDARD-CONTROL) ................................. 6

3.1.1 POWER SUPPLY ....... ............................................................................................................... 6

3.1.2 START/STOP ............................................................................................................................. 7

3.1.3 SPOT WELDING ......................................................................................................................... 7

3.1.4 WIRE FEED SPEED / SOFT START .......................................................................................... 8

3.1.5 MOTOR CONTROL ................................................................................................................... 8

3.1.6 BURNBACK TIME, CONTACTOR, GAS VALVE ...................................................................... 9

3.1.7 THERMAL OVERLOAD CUTOUT ............................................................................................. 9

3.2 V/A-METER OPTION (STANDARD CONTROL) ........................................................................... 10

4.TECHNICAL DATA ............................................................................................................................... 12

5. LOAD CHARACTERISTIC ................................................................................................................... 12

6. INSTALLATION .................................................................................................................................. 13

7. INSTRUCTION FOR USE .................................................................................................................... 13

8. MAINTENANCE ................................................................................................................................... 14

9. ACCESORIES ...................................................................................................................................... 14

9.1 INSTRUMENT SET KIT VA-MET13 .............................................................................................. 14

10. SPARE PARTS LIST ......................................................................................................................... 16

INTRODUCTION

This service manual is intended for use by technicians with electrical training. Use it for fault - tracing and

repair.

Use the diagrams in section 1 and the description of operation in section 3 respectively – when fault-tracing.

A brief user guide is included in section 7 to assist understanding how the machine is used.

The manual contains details of design up to and including September 2000.

! WARNING !

ARC WELDING AND CUTTING CAN BE INJURIOUS TO YOURSELF AND OTHERS. TAKE

PRECAUTIONS WHEN WELDING. ASK YOUR EMPLOYER FOR SAFETY PRACTICES THAT SHOULD

BE BASED ON MANUFACTURER’S HAZARD DATA.

ELECTRIC SHOCK - Can kill

- Install equipment in accordance with obligatory standards.

- Do not touch live electrical parts or electrodes with bare skin, wet gloves or wet clothes.

- Insulate yourself from earth and workpiece.

- Ensure your work position is safe.

FUMES AND GASES - Can be dangerous to your health

- Keep your head away from fumes.

- Use ventilation and/or extraction to keep fumes and gases away from your breathing zone

and surroundings.

ARC RAYS - Can injure eyes and burn skin

- Protect your eyes and skin. Use correct welding screens, filter lens and wear protective clothes.

- Protect bystanders with suitable screens or curtains.

FIRE HAZARD

- Sparks (spatter) can cause fire. Make therefore sure there are no inflammable materials nearby.

NOISE - Excessive noise can damage your hearing.

- Protect your ears. Use ear defenders or other hearing protection.

- Warn bystanders of the risk.

READ AND UNDERSTAND THE INSTRUCTION MANUAL BEFORE INSTALLING OR OPERATING UNIT

PROTECT YOURSELF AND OTHERS !

CONNECTION DIAGRAM, LKB160, 230V

Switch positions for switch Q1

01234567

1-2 xxxxxxx

3-4 xxxxxxx

8-19 x

12-19 x

16-19 x

20-19 x

6-19 x

10-19 x

14-19 x

COMPONENT DESCRIPTION

A1 Control circuit board M1 Fan

A2 VA - meter circuit board M2 Drive unit motor

T1 Transformer V2 Rectifier bridge

V1 Diode bridge B1 Temperature switch

L1 Inductor S1 Welding gun

RI Shunt RP1 Wire speed reference potentiometer

K1 Contactor RP2 Spot-welding potentiometer

Q1 Rotary cam switch R27 Burnback potentiometer

T2 Control transformer H1/H2 LED (green/red)

C1,C2,C3 Capacitor 0,1uF/275V T3 Transformer

R1 Resistor 3,3k 1W F4 Fuse 4A slow-blow

F1,F3 Fuse 2,5A slow-blow XG Terminal block

F2 Fuse 6,3A slow-blow

LKB 160, 230V

2. COMPONENT POSITIONS - CONTROL CIRCUIT BOARD LKC13C (A1)

3. CONTROL CIRCUIT FUNCTION

NOTE: All diagrams and function descriptions below are valid for both LKC13 and LKC12 unless

otherwise specified.

3.1 DESCRIPTION OF OPERATION - PCB LKC13 (LKC12) (STANDARD-CONTROL)

Sections 3.1.1- 3.1.7 below refer to the diagrams in chapter 1.

3.1.1 POWER SUPPLY

The circuit board uses one supply voltage: 31VAC – rectified by V1 for power supply to the motor.

• Power supply to the electronic circuitry

The +42VS power supply from diode V7 through R43, R44 – is regulated to 15V by voltage regulator A2.

• +42V/+42VS power supply

+42V – is used for motor control, relay K1 (on PCB) and indication (LED - on front panel)

+42VS – is used for powering of auxiliary control circuits (see next sections)

These voltages may vary (with load/mains voltage deviation) – from –15% to +10%.

3.1.2 START/STOP

Closing contact S1 on the welding torch starts the welding process. The LKB 160 provides only two-stroke

control mode.

START/STOP SEQUENCE, 2-STROKE

3.1.3 SPOT WELDING

The LKB 160 has a spot–welding capability. It is active when the switch in potentiometer RP2 is closed. Spot

welding time is adjustable between 0,5 and 4 seconds.

If the welding torch trigger switch is released while a spot weld is being made, the welding sequences will be

interrupted. If the switch is held closed for longer than the spot weld time, welding stops when the spot weld

time is up. To restart, the switch must be released and then operated again.

3.1.4 WIRE FEED SPEED / CREEP START

The wire feed speed adjustment range is 1,4 to 19 meter/minute.

The +5,1V reference voltage (±

±±

±1%) is derived from the PWM circuit, which generates gate pulses for the

motor drive transistor.

There is built-in „creep-start” function -i.e. welder may start welding with reduced wire speed and after ca

0,35 sec speed rise up automatically to the value pre-set by RP1. Initial speed (50% - 100% - 70%) – is

selected by switch S1 – accessible from drive compartment.

Note !: - when welding in low voltage range (pos.”1” & “2” of switch Q1(A) - selector S1 to be set onto 100%,

then active automatic “speed-up impulse” - to improve arc ignition; its duration - if necessary -is adjusted by

potentiometer R82 on the PCB ( not shown here), - factory setting is:- 30% speed increase for ca 320msec.

V-REF voltage is reference signal for motor speed control circuit.

3.1.5 MOTOR CONTROL

The motor is powered by the smoothed +42 V supply. Pulse width modulation of transistor V11 controls the

motor voltage. The pulse frequency is about 16 kHz, and maximum conduction time of the pulses is about

95% of the pulse cycle time. During the Off parts of the pulse cycle, the motor current freewheels through

diode V12.

At 24V motor supply voltage, the wire feed roller speed is 160 r/min ±5%. At a roller speed of 200r/min, the

wire feed speed is 19 m/min ±5%.

• Speed control

The gate pulses to transistor V11 are generated by a PWM circuit, which compares speed reference with

signal proportional to the motor voltage.

• Current limit

The current limit is set at 6,0 A. the motor current is measured by resistor R42 that produces a voltage

drop proportional to the current (1A = 33mV). The current limit restricts the conduction time of the gate

pulses to transistor V11.

• Compensation of motor I x R voltage

Potentiometer R53 allows compensating voltage drop on motor armature resistance so as to improve

wire transportation at low speed settings.

Warning: too high setting may cause drive control instability! Recommended setting of R53 is 0,70.

3.1.6 BURNBACK TIME, CONTACTOR, GAS VALVE

• BURNBACK TIME

The burnback time is the time from when motor braking starts until the main contactor opens. When

welding stops, capacitor C9 is discharged through potentiometer R27 and resistor R28. The burnback

time can be adjusted from 0 to 0,35 seconds

• ENERGISING THE CONTACTOR AND GAS VALVE

Contactor and gas valve are switched - on by relay K1, which is controlled by transistor V6.

R35 and R34 – reduce the voltage on the coil of K1 (rated value – 24V DC)

3.1.7 THERMAL OVERLOAD CUTOUT

The thermal overload cutout B1 is mounted on the surface of the T1 transformer winding – and operates at a

temperature of 90°C.

When B1 operates (contact opens) – “ALARM” – signal goes high (11,5 – 15V), the output signals from the

board are disabled and red LED indicates the overload.

When the equipment cool-down – B1 resets automatically.

NOTE: Both LED (Power ON and OVERLOAD) are located in common case, so the mixed light green and

red is seen as orange colour – when the overload is indicated!

3.2 V/A-METER OPTION (STANDARD CONTROL)

NOTE: All diagrams and function descriptions below are valid for both VA-Met12 and VA-Met13 unless

otherwise specified.

COMPONENT POSITIONS - CIRCUIT BOARD VA-MET13 (A2)

V/A-meter for measuring of welding voltage or current (readout is selected by switch S1 on the front of meter)

may be installed as optional accessory. (Assembling details – see section 9.1, connections are also shown in

section 1).

V/A-meter is supplied with 11VAC; input signal for current is delivered from standard 60mV shunt, voltage is

measured directly across welding rectifier output.

Depending on required current range (determined by applied shunt rating) – the jumpers X3&X4 on the PCB

must be properly arranged, and the reference voltage U-REF must be adjusted by R4 – as indicated in the

diagram herewith (see the table).

Voltage indication is adjusted by potentiometer R1 on the PCB.

(Note: voltage adjusting is to be made only when jumpers and U-REF setting is completed!)

Recommended voltage metering range is: 0V to –40V. (Calibration is performed for –25V).

Recommended current input range is: 0mV to +60mV. (Calibration for 60mV)

V/A meter has “HOLD” function – i.e. after stop of welding, there is memorised the last displayed value

(current or voltage – depending on S1 position).

There is also possibility to compensate the voltage drop on current wires – i.e. to get indication of the actual

welding arc voltage.

Compensation is adjusted by potentiometer R28 (on the bottom side of PCB); when utmost CCW position –

there is no compensation, turning CW increases the compensation step.

NOTE: Factory setting is “no compensation”, if necessary – use reference voltmeter and artificial load – so as

to adjust compensation depending on wire length.

4.TECHNICAL DATA

Mains voltage 1x230 V, 50Hz

Mains fuse 16 A delayed

Rated power consumption 5,7 kVA

Rated welding current Duty cycle* 45% 130 A

Duty cycle* 60% 112 A

Duty cycle* 100% 87 A

Welding current range

28A/15,4V÷130A/20,5V

Open circuit voltage

18÷28V

Enclosure class IP 23

Application class

Dimensions length

width

height

770

520

620

Weight 73,5 kg

*Duty cycle is based on 10-minute period. Duty cycle 45% means that after 4,5 minutes of unit operation,

5,5 minutes brake is required. Duty cycle 100% means that the unit can work continuously.

Warning:

The unit is characterised by the following:

- Enclosure class IP 23 indicates that the unit is designed for indoor and outdoor use.

- Application class S means that the unit is designed for use in areas of elevated electric hazard.

5. LOAD CHARACTERISTIC

6. INSTALLATION

A competent and authorised person must install the equipment.

Connect the mains cable, and protect it with the appropriate fuses, in accordance with regulations.

Make sure that the power unit is not covered or installed such that cooling is impeded.

PRIMARY CURRENT, MAINS FUSE AND MAINS CABLE

Voltage 230V

1~ 50/60 Hz

Primary current at:

100% duty cycle 8A

60% duty cycle 10A

45% duty cycle 22A

Conductor

3x1,5mm²

Fuse, slow-blow

16A

7. INSTRUCTION FOR USE

The LKB 160 is step-switched welding power unit, intended for welding with solid filler wires of steel,

stainless steel or aluminium, and cored wires with or without shielding gas.

The power units can be fitted with an instrument for display of current and voltage. It incorporates a hold

function.

A thermal overload cutout protects against overheating. The cutout resets automatically when the unit has

cooled.

0 20 40 60 80 100 120 140 160

I2(A)

U2(V)

CONTROL PANEL

A. POWER SWITCH ON/OFF AND WELDING VOLTAGE ADJUSTMENT– Turning this switch from 0 to

one of seven steps (1÷7) applies power to the unit. The green LED diode (B) will illuminate indicating that

power is supplied to the equipment. Cooling fan will also be switched on. Welding voltage adjustment is

carried out by means of turning this switch.

WARNING: Operating this switch during the welding process (loaded power source) can cause

damage to unit!

B. OVERHEATING The orange signal LED diode will illuminate in the event of overheating. The welding

output is automatically disabled until the LKB reaches normal temperature. Should this indicator

illuminate leave the power source a few minutes to cool down. Do not switch the power source off as this

will remove power from the cooling fans. The unit will be ready to resume welding when the orange

indicator has changed to green.

C. DIGITAL METER indicates actual values of welding current or voltage. The toggle switch allows you to

select either voltage or current display. The LKB 160 is supplied without a meter. The meter kit is

supplied as an optional extra and has a last reading hold facility.

D. POTENTIOMETER with switch – to switch on spot welding and impulse time (for spot welding) – in the

range of 0,5 ÷ 4 s.

E. POTENTIOMETER to set wire feed speed (in the range of 1,4 ÷ 19 m/min).

F. POTENTIOMETER of burnback time regulation

G. CONNECTION (Euro connection) to connect welding torch

H. OUTPUT SOCKET to connect current cable with clamp

I. MODE SELECTOR (CREEP START) 50% - 100% - 70%

8. MAINTENANCE

Regular maintenance is important for reliable, safe operation.

• Blow the power until clean with dry compressed air at reduced pressure.

• For problem-free wire feed, clean and replace the wearing parts in the wire feed mechanism regular

intervals.

Note that an excessive pressure setting can cause abnormal wear on the drive roller, feed roller and wire

conduit.

• Blow the wire conduit clean at regular intervals and clean the gas nozzle.

9. ACCESSORIES

9.1 INSTRUMENT SET KIT VA-MET13 (0349 302 078)

V/A METER ASSEMBLY INSTRUCTION

− Take off side panels of unit.

− Fasten the meter to front part of unit.

− Assemble cover of meter to partition of unit.

− Disassemble bridge rectifier.

− Disconnect current cable (+) from the bus.

− Connect shunt to bus and next connect current cable (+) to free end of shunt.

− Assemble bridge rectifier in unit.

− Connect wiring of meter according to schematic diagram of LKB 160.

1- VA -Meter A2

2- Shunt

3- Bus

4- Wiring for circuit board A1

5- Wiring for transformer T2

6- Wiring for shunt and current socket (-)

7- Current cable (+)

8- Current socket (-)

9- Bridge rectifier

9.2 TRANSFORMER SET FOR CO

–HEATER (O/N 349 302 080)

ASSEMBLING INSTRUCTION

− Take off side panels of unit.

− Install transformer T3 and terminal block XG in places marked with arrows.

− Connect wiring of transformer T3 to components according to schematic diagram of unit.

1- Transformer T2

2- Transformer T3

3- Terminal block XG

4- Wiring for Q1 and T2

10. SPARE PARTS LIST

LKB 160 1x230V (50Hz) ordering no. 0349 302 081

Item no. Qty Ordering no. Denomination Notes

0349 302 103

0349 302 089

0349 302 090

0349 302 094

0349 302 095

0349 302 092

0349 302 093

0349 302 091

0457 290 003

0455 172 001

0455 174 001

0455 457 001

0455 467 001

0160 362 881

0349 302 119

0458 004 001

0456 031 004

0456 031 002

0469 516 003

0349 302 180

0192 859 126

Front panel

Panel

Rotary cam switch

Potentiometer

Knob

LED (green/red)

LED-holder (socket)

Protection glass

Seal

Wheel

Castor wheel

Current connector-socket

VA-meter circuit board

Cover lid

Side plate

Shaft

Clamp

Locking washer

RP1

RP2

H1/H2

Item no. Qty Ordering no. Denomination Notes

0349 302 120

0349 302 122

0349 302 098

0349 302 099

0469 662 880

0457 289 027

0349 302 202

0193 054 002

0457 290 042

0321 173 001

0455 986 001

0349 302 179

Shunt

Bus

Transformer

Inductor

Diode bridge

Fan

Control circuit board

Gas valve

Temperature switch

Chain

Shelf

Bottom plate

Item no. Qty Ordering no. Denomination Notes

0455 890 892

0146 967 881

0349 302 096

0349 302 097

0457 290 046

Wire feeder

Brake hub

Control transformer

Contactor

Rectifier bridge

Item no. Qty Ordering no. Denomination Notes

6,3A (slow)

2,5A (slow)

0349 302 102

0457 288 029

0457 288 030

0455 833 001

0349 302 181

Fuse element

Mains cable

Cable gland

Locknut

Handle

Rear panel

ESAB LKB 160 User manual

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