ESAB LUD 320 User manual

0740 800 106

Valid for serial no. 716--xxx--xxxx to 852--xxx--xxxx030314

LUD 320

LUD 450

Service manual

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LIST OF CONTENTS Page

READ THIS FIRST 3...............................

WARNING 4......................................

COMPONENT DESCRIPTION 5.....................

WIRING DIAGRAM LUD 320/450 8..................

AP1 DESCRIPTION OF OPERATION 10..............

AP1 CIRCUIT DIAGRAM 11.........................

AP1 COMPONENT POSITIONS 14..................

FITTING COMPONENTS ON THE HEAT SINK 15......

AP2 COMPONENT POSITIONS 16...................

AP2 DESCRIPTION OF OPERATION 18..............

SOFT STARTING 32................................

AP5 DIAGRAM AND COMPONENT POSITIONS 33....

AP6 COMPONENT POSITIONS 34...................

AP6 DESCRIPTION OF OPERATION 35..............

SETTING UNIT 40..................................

WIRING DIAGRAM, SETTING UNIT 41................

AP1B, COMPONENT POSITIONS 43.................

AP3B, DIAGRAM AND COMPONENT POSITIONS 44..

REPLACING THE BATTERY 45......................

FAULT LOG 46.....................................

FAULT CODES 48..................................

SERVICE FUNCTIONS 54...........................

LOAD CHARACTERISTICS 70.......................

TECHNICAL DATA 71...............................

INSTALLATION 72..................................

CONTROL PANEL AND CONNECTIONS 75...........

MAINTENANCE 76.................................

SPARE PARTS LIST 77..............................

ACCESSORIES 92..................................

NOTES 94.........................................

Rights reserved to alter specifications without notice.

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READ THIS FIRST

Maintenance and repair work should be performed by an experienced person, and electrical

work only by a trained electrician. Use only recommended replacement parts.

This service manual is intended for use by technicians with electrical/electronic training for

help in connection with fault--tracing and repair.

Use the wiring diagram as a form of index for the description of operation. The circuit

boards ar e divided into numbered blocks, which are described individually in more detail in

the descriptions of operation. All component names in the wiring diagram are listed in the

component description.

This manual contains details of all design changes that have been made up to and including

February 2003.

The LUD 320 and LUD 450 are designed and tested in accordance with international

and European standard 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 requirements

of the above standard.

INTRODUCTION

The LUD 320 and LUD 450 are transistor--controlled welding rectifier power units, intended

for MMA, MIG/MAG, TIG welding and CAG (Carbon Arc Gouging). They are used

together with a setting unit and MEK 4C, MEK 44C, MEK 20C or MLC 30C wire feed unit.

The wire feed units have their own service manuals.

The design features, construction and method of operation of the setting unit are described in

this manual. A description of its use, however, is in a separate programming manual.

The programming manual is available in t he following languages: Swedish, Danish,

Norwegian, Finnish, English, German, French, Dutch, Spanish, Italian, Portuguese, Greek

and Czech.

The ordering no. of the manual is different depending on language and software version.

Please contact ESAB for a list of available manuals.

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WARNING

Many parts of the power unit are at mains voltage.

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 BE

BASED ON MANUFACTURERS’ HAZARD DATA.

ELECTRIC SHOCK -- Can kill

S Install and earth the welding unit in accordance with applicable s tandards.

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 s tance is safe.

FUMES AND GASES -- Can be dangerous to health

S 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 HAZARD

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

NOISE -- Excessive noise can damage hearing

S 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!

INSTRUCTIONS

Straps must be used when lifting the power source.

The handle is solely intended for pulling the power

source.

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COMPONENT DESCRIPTION

WARNING !

STATIC ELECTRICITY can damage circuit

boards and electronic components.

S

SS

S Observe precautions for handling electrostatic

sensitive devices.

S

SS

S Use proper static--proof bags and boxes.

ESD

This component description refers to the diagram on page 8.

AP1 Power board; see the f unction description on page 10.

AP2 Control circuit board; see the function description on page 18.

AP3 Connection board, for communication with the setting unit, wire feed unit

and remote control device.

AP4 Hall effect sensor, 1 V / 100 A

AP5 Circuit board, suppression (EMC). See circuit diagram on page 33.

AP6 Circuit board for TIG welding; see the function description on page 35.

AP7 HF device, output voltage: 500V peak. Only on machines with TIG

welding capability.

C1 -- C2 Capacitor, decoupling.

C3 Start and run capacitor for pump motor M1.

C4 Start and run capacitor for fan EV2.

C5 Capacitor, decoupling.

C6 Capacitor, for speed reduction of cooling fan EV2.

C7 Capacitor, C7 and R3 smooth the no--load voltage for MMA welding.

C8 Capacitor, decoupling.

EV1 Fan, 24 V DC. Cools circuit board AP1.

EV2 Fan, 230 V AC.

FU1 MCB, 10 A, protects the 42 V supply to the wire feed unit.

FU2 Fuse, 2A, slow--blow. Protects fan EV2, pump motor M1 and HF

generator AP7.

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HL1 Indicating lamp on the front of the machine. Lights when the main

On/Off switch QF1 is on.

L1 Primary inductor. Filters the mains voltage and improves the power

factor.

L2 Secondary inductor. Its inductance exceeds 10 µH at high currents and

about 60 µH at low currents.

L3 2+4+4 ferrite rings. Reduce transients to/from transfor mer TM1. See also

V1 below and AP1:3 on page 10.

L4 Ferrite ring. Suppresses interference in the signal fr o m Hall effect sensor

AP4. The wires from AP4 must be wound four turns around the ring.

M1 Pump motor. Only on the LUD 320W/450W.

Q1 -- Q2 IGBT modules. See AP1:4 on page 12 and the instructions on page 15.

QF1 Main power supply switch.

QF2 Cooling water pump switch. Only on 320W/450W.

R2 Resistor. Discharges capacitor C7 when the no--load voltage is turned off.

R3 Resistor. With C7, it smooths the no--l oad voltage for MMA welding.

SL1 Flow switch for cooling water (accessory). See AP2:11 on page 31.

ST1 Thermal switch: see AP2:9 on page 30, and the fitting instructions

on page 15.

ST2 Thermal switch: controls the fan speed. See AP2:10 on page 30.

ST3 Thermal switch; see AP2:9 on page 30.

TA1 Current transformer, 400:1. Note that it must never be run with open--

circuited secondary. See also AP2:4 on page 24.

TC1 Control power supply tr ansformer.

TM1 Main transformer. See AP1:3 on page 10.

TV1 HF transformer. The primary winding has one turn, and the secondary

winding has 26 turns. The unloaded secondary winding is about 13 kV

peak.

When fitting the transformer it is important that the air gaps in the trans-

former cores are correct. See item 621 in the spare parts list.

Fitted only to machines with TIG welding capability.

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V1 Diode modules with secondary diodes. There are five diode modules in

the LUD 450 and four in the LUD 320.

Each module consists of two diodes. The transient voltages produced

when the diodes turn off are suppressed by eight ferrite rings, i.e. four in

each diode leg.

If one diode module is faulty, replace all diode modules.

See page 15 for fitting instructions for V1.

V2 (TY1) Thyristor module. See AP2:8 on page 29 and the instructions on page 15.

V3 LED, yellow. Indicates overtemperature. See AP2:9 on page 30.

VC1 (BR1) Rectifier bridge. See fitting instructions on page 15.

XP1 -- XP3 Connectors (male).

XP36 Connector (male).

XS1 -- XS17 Connector (female).

XS18 -- XS20 Connector, OKC 50

XS21, XS22 Connector (female).

XS25 -- XS28 Connector (female).

XS29 Central connector for TIG welding.

XS30 Connector, OKC 50 HF, for TIG welding.

XS31 -- XS35 Connector (female).

XT1 -- XT4 Terminal block.

YV1 Solenoid valve. Only on machines with TIG welding capability.

WIRING DIAGRAM LUD 320/450

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AP1 DESCRIPTION OF OPERATION

Circuit board AP1 is the mother board in the power section of the power unit. The

components of the power section are mounted on a cast heat sink.

If the IGBT modules, circuit board AP1 and/or circuit board AP2 are replaced, the gate

pulses must be checked and the machine must be soft--started: see pages 26 and 32.

AP1:1 THE MAINS POWER UNIT

The mains voltage is rectified by rectifier VC1. Primary inductor L1

improves the power factor and increases resistance to mains--borne

transients.

Smoothing condensers C12 -- C15 charge up through r esistors R3 and R4

when the power is turned on. The two resistors are short--circuited by

thyristor TY1 (V2) about 1.2 seconds after starting. If the thyristor fails to

do this, the two resistors could be burnt out when load was applied to the

machine. Their ratings are 12Ω 10 W each and their ordering number is:

0193 775 114.

Resistors R5 and R9 form a potential divider / discharge resistor for

capacitors C12 -- C15.

See page 15 for instructions on fitting VC1 and TY1 (V2).

AP1:2 CAPACITIVE POTENTIAL DIVIDER

Capacitors C1 and C2 f orm a capacitive potential divider for the centre

point to which the main transformer is connected. Resistors R1 and R2 are

discharge / potential divider resistors.

AP1:3 MAIN TRANSFORMER

The transformer is strip--wound, with four primary tur ns and 1 + 1

secondary turns.

Its core has an air gap of about 0.13 mm, which is of key importance for

operation of the entire inverter. It must not be reduced or eliminated.

Two ferrite ri ngs, L3, are fitted to the conductors connected to the primary

winding. Their purpose is to attenuate current transients arising from

operation of the IGBT transistors.

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AP1 CIRCUIT DIAGRAM

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AP1:4 IGBT

The switching components in the power section consist of two IGBT

modules, Q1 and Q2, operating at a fixed switching frequency of 20 kHz.

The IGBT modules must never be energised when the gate conductors are

disconnected.

Fitting instructions are given on page 15.

If the IGBT modules have failed, we recommend that the mains rectifier,

VC1, should also be replaced.

AP1:5 TRANSIENT PROTECTION

An RCD filter protects against transients produced by turn--off of the IGBT

modules. It consists of components R18, R19, C10, C11, D1 and D2.

AP1:6 THEGATECIRCUIT

The IGBT transistors are each driven by their own gate circuits. These

circuits are galvanically isolated from control circuit board AP2 by

transformers TR1 and TR2.

Fuses F1 and F2 protect the gate drive circuits if the power unit should fail.

Instructions for checking the gate pulses can be found on page 26.

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AP1 CIRCUIT DIAGRAM

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AP1 COMPONENT POSITIONS

The drawing above shows the positions of the contacts on the first and second versions of

circuit board AP1.

On the first version, all the contacts on the board are 10 mm high. On the later versions,

contacts B, C and N are 14 mm high, while contact B has also changed places with contact

PE. The arrows, on the diagram above, are pointing out the contacts.

When fitting this board in machines that have been originally supplied with the first version,

fit the connectors to the following board contacts: XS1 on PE, XS2 on PF and XS4 on PB.

See the circuit diagram on page 11.

Contacts XS1 and XS2 must be secured to the board by means of a cable tie.

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FITTING COMPONENTS ON THE HEAT SINK

Thermally conducting grease

A layer of thermally conducting grease must be applied to the components described below

before they are fitted.

Start by cleaning the heat sink, and then apply a thin, even layer of grease to the contact

surface of the component. The purpose of this grease is to fill any hollows in the surface of

the component and the heat sink: those parts of the component and the heat sink that are in

true metallic contact may have such contact.

Fit the components as described below.

The order ing number for the thermally conducting grease is given on page 84 of the spare

parts list. Only the grease recommended by us may be used.

Fitting instructions

Q1, Q2 IGBT MODULES

The IGBT modules are extr emely sensitive to ESD. Never touch a module

having an open gate input. Apply appropriate ESD protection measures

when fitting the modules.