ESAB LKB 220 User manual

Brand: ESAB

Model: LKB 220

Category: Welding System

Type: User manual

0349 300 026

010126

LKB 220

Service manual

1. CONNECTION DIAGRAM, LKB220, 400V ......................................................................................... 4

2. COMPONENT POSITIONS, CIRCUIT BOARD LKC12 (A1) ............................................................. 6

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

3.1 DESCRIPTION OF OPERATION-PCB LKC12 (STANDARD-CONTROL) ..................................... 6

3.1.1 POWER SUPPLY ....... ............................................................................................................... 7

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

3.1.3 SPOT WELDING ......................................................................................................................... 8

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

3.1.5 MOTOR CONTROL ................................................................................................................... 9

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

3.1.7 THERMAL OVERLOAD CUTOUT ............................................................................................. 10

3.2 V/A-METER OPTION (STANDARD CONTROL) ........................................................................... 11

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

5. LOAD CHARACTERISTIC ................................................................................................................... 13

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

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

8. MAINTENANCE ................................................................................................................................... 15

9. ACCESORIES ...................................................................................................................................... 15

10. SPARE PARTS LIST ......................................................................................................................... 17

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, LKB220, 400V

Switch positions for switch Q2 Switch positions for switch Q3

COMPONENT DESCRIPTION

A1 Circuit board LKC12 M1 Fan

A2 V/A - meter M2 Drive unit motor

T1 Transformer V2 Rectifier bridge

V1 Diode bridge B1 Temperature switch

L1 Inductor

R2 Resistor 0,6 Ω

RI Shunt S1 Welding gun

K1 Contactor RP1 Wire speed reference potentiometer

Q1 Rotary cam switch RP2 Spot-welding potentiometer

Q2 Rotary cam switch R27 Burnback potentiometer

Q3 Rotary cam switch H1/H2 LED (green/red)

T2 Control transformer T3 Transformer

C1,C2,C3 Capacitor 0,1uF/275V F4 Fuse 4A slow-block

R1 Resistor 3,3k 1W XG Terminal block

F1,F3 Fuse 2,5A slow-blow

F2 Fuse 6,3A slow-blow

LKB220

400-415V ~3 50/60Hz

LKB220

230V ~3 50/60Hz

2. COMPONENT POSITIONS, CIRCUIT BOARD LKC12 (A1)

3. CONTROL CIRCUIT FUNCTION

3.1 DESCRIPTION OF OPERATION - PCB 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 220 provides only two-stroke

control mode.

START STOP SEQUENCE, 2-STROKE

3.1.3 SPOT WELDING

The LKB 220 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 / SOFT 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 „soft-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.

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 which 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 LEDs (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)

COMPONENT POSITIONS, CIRCUIT BOARD VA-MET12 (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) – first 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). The final adjusting of U-REF is necessary so as to calibrate accurate

current indication (S1 in position for current display):

- apply 60mV signal to inputs X1:2 (+) and X1:3(-) using reference voltmeter,

- adjust R4 – so as to display value of current corresponding to shunt rating – 150A, 250A or 400A (jumper

X4 in correct position!)

When current calibration is completed, change-over the S1 to voltage position (locate jumper X3 properly!)

and perform voltage calibration.

Voltage indication is adjusted by potentiometer R1 on the PCB – comparing with reference voltmeter at the

input.

(Note: voltage adjusting is to be made only when jumpers are properly located 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)

(Note: the above described procedure is applied only when re-calibration of the factory settings is

necessary!)

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 the wire length.

4.TECHNICAL DATA

400-415V, 3~50/60 Hz 230V, 3~50/60 Hz

Mains voltage 3x400 V, 50/60 Hz 3x230 V, 50/60 Hz

Mains cable cross-section 4x1,5 mm

4x2,5 mm

Mains fuse 10 A delayed 20 A delayed

Rated power consumption 9,7 kVA

Rated primary current P30% 12 A 21 A

Rated welding current Duty cycle* 30% 220 A

Duty cycle* 60% 155A

Duty cycle* 100% 120 A

Welding current range

20÷220 A

Open circuit voltage 14-32 V

Enclosure class IP 23

Application class

Dimensions Length

Width

Height

770

520

620

Weight 90 kg

*Duty cycle is based on 10-minute period. Duty cycle 30% means that after 3 minutes of unit operation,

7 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 400V

3~ 50 Hz

230V

3~ 50 Hz

Primary current at:

100% duty cycle 5A 8,6A

60% duty cycle 7A 12A

30% duty cycle 12A 21A

Conductor

4x1,5mm

4x2,5mm

Fuse, slow-blow

10A 20A

7. INSTRUCTION FOR USE

The LKB 220 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 sample-

and-hold function.

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

cooled.

0 20 40 60 80 100 120 140 160 180 200 220

I2(A)

U2(V)

CONTROL PANEL

A. POWER ON/OFF SWITCH Turning this switch to the “I” position applies power to the unit. The green

LED diode (pos. B) will illuminate indicating that power is supplied to the equipment. Cooling fan will also

be switched on.

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

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

indicator has changed to green.

C. WELDING VOLTAGE ADJUSTMENT is carried out by means of coarse control 3-position switch, and

fine control 7-position switch. It is therefore possible to select 21 different welding voltage outputs.

WARNINR: Operating these voltage switches during the welding process (loaded power source) can

cause damage to the unit.

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

select either voltage or current display. The LKB 220 is supplied without a meter. The meter kit is

supplied as option extra and has a last reading hold facility.

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

range of 0,5 ÷ 4 s.

F. POTENTIOMETER to set wire feeding speed – in the range of 1,4 ÷ 19 m/min.

G. POTENTIOMETER of burnback time regulation (0÷0.35 s)

H. CONNECTION (Euro connection) to connect welding torch

I. CURRENT SOCKETS to connect current cable with clamp

J. MODE SELECTOR: 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.

WARNING!: If periodical HV tests have to be carried-out according to local safety regulations (in

some countries obligatory!) – the following circuits must be isolated during the test by means of

disconnecting connectors:

- X2:1,2(A1)

- X2:5,6(A1)

- X5(A1)

- X6(A1)

- X7(A1)

9. ACCESSORIES

9.1 INSTRUMENT SET KIT VA-MET12 (O/N-349 302 079)

V/A METER ASSEMBLY INSTRUCTION

1. Take off side panels of unit.

2. Fasten the meter to front panel of unit.

3. Assemble cover of meter to partition of unit.

4. Disassemble inductor.

5. Disassemble bridge rectifier.

6. Disconnect current cable (+) from the bus.

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

8. Assemble bridge rectifier in unit.

9. Assemble inductor.

10. Connect wiring of meter according to schematic diagram of LKB 220.

1- Meter VA-MET12

2- Shunt

3- Bus

4- Wiring for LKC12

5- Wiring for transformer T2

6- Wiring for shunt and current socket cable(

)

7- Current cable (+)

8- Rectifier bridge

9- Inductor

10- Current socket cable (

)

9.2 TRANSFORMER SET FOR CO

–HEATER (0349 302 080)

ASSEMBY INSTRUCTION

1. Take off side panels of unit.

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

3. Connect wiring to transformer T3 and 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

Item no.

Qty

LKB220

400-415V

Qty

LKB220

3x230V

Ordering no. Denomination Notes

0349 302 103

0349 302 104

0349 302 157

0349 302 105

0349 302 183

0349 302 106

0349 302 182

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

Circuit board VA-MET 12

Cover lid

Side plate

Shaft

Clamp

Locking washer

RP1

RP2

H1/H2

Item no.

Qty

LKB 220

400-415V

Qty

LKB 220

3x230V

Ordering no. Denomination Notes

0349 302 128

0349 302 107

0349 302 186

0349 302 108

0349 302 110

0457 289 027

0349 302 100

0193 054 002

0457 290 042

0349 302 121

0349 302 170

0321 173 001

0455 986 001

0349 302 179

Cover of board

Transformer

Inductor

Diode bridge

Fan

Circuit board LKC12

Gas valve

Temperature switch

Shunt

Bus

Chain

Shelf

Bottom plate

Item no.

Qty

LKB 220

400-415V

Qty

LKB 220

230V

Ordering no. Denomination Notes

0455 890 892

0146 967 881

0349 302 096

0349 302 129

0349 302 187

0457 290 046

Wire feeder

Brake hub

Control transformer

Contactor

Rectifier bridge

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ESAB LKB 220 User manual

Brand: ESAB

Model: LKB 220

Category: Welding System

Type: User manual

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ESAB LKB 220 User manual

ESAB LKB 220 User manual

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