ESAB LHF 405 PIPEWELD User manual

0349 300 070 Valid for serial no. 422, 423--xxx--xxxx071024
LHF 405 PIPEWELD
LHF 615 PIPEWELD
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READ HISFIRS 3.................................................................
IN RODUC ION 3...................................................................
ECHNICALDA A 4.................................................................
WIRINGDIAGRAM,LHF405PIPEWELD 5.............................................
Componentdescription 5..........................................................
LHF405PIPEWELD 7.............................................................
WIRINGDIAGRAM,LHF615PIPEWELD 8.............................................
Componentdescription 8..........................................................
LHF615PIPEWELD 10.............................................................
DESCRIP IONOFOPERA ION 11.....................................................
LH20/1controlboard 11............................................................
LH20/1:1 Currentsetting 11.........................................................
LH20/1:2 Currentandvoltagemeter 12...............................................
LH20/1:3 Functional control circuit ANTI TICK, HOT TART, ARCFORCE 13. . . . . . . . . . . . . .
LH20/1:4 TIGmodeoperation 14.....................................................
LH20/1:5 Wireless remote current control receiver 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LH20/1:6 Powersupply 16...........................................................
LH20/1:7 Regulator and current shunt amplifier 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LH20/1:8 ynchronisation and thyristors firing 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LH20/1:9 Thermaloverloadcircuit 18.................................................
LH20/1--Componentslayout 19......................................................
LH10/2--Componentslayout 20......................................................
CHECKINGANDCALIBRA IONPROCEDURES 21......................................
SERVICEINS RUC IONS 23..........................................................
WhatisESD? 23...................................................................
hermal switch (thermostat) replacement procedure 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INS RUC IONS 25...................................................................
SAFE Y 25........................................................................
INS ALLA ION 26....................................................................
Connectingtomains 26............................................................
Assemblyofcomponents 28........................................................
OPERA ION 29.......................................................................
Controlsandconnections 29.......................................................
MMAwelding 30...................................................................
IGwelding 30.....................................................................
ArcAirGouging 30.................................................................
Overheatingprotection 30..........................................................
MAIN ENANCE 31....................................................................
ORDERINGOFSPAREPAR S 31......................................................
NO ES 32...........................................................................

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READ HIS FIRS
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
board is divided into numbered blocks, which are described individually in more detail in
the description 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 October 2007.
he LHF 405 PIPEWELD and LHF 405 PIPEWELD are designed and tested in
accordance with international and European standards IEC/EN 60974--1 and
IEC/EN 60974--10.
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.
IN RODUC ION
LHF 405/615 PIPEWELD are thyristor controlled welding rectifiers designed for
welding with coated electrodes, TIG welding and arc air gouging.
The welding rectifiers can be used with the following remote control devices: N02,
MMA1, MMA2, AT1, AT1 CoarseFine.
LHF 405/615 PIPEWELD are versions with meters, that allow current and voltage
settings to be read from the front of the rectifier.
Do not dispose of electrical equipment together with normal waste!
In observance of European Directive 2002/96/EC on Waste Electrical and Electronic
Equipment and its implementation in accordance with national law, electrical equipment
that has reached the end of its life must be collected separately and returned to an
environmentally compatible recycling facility. As the owner of the equipment, you should
get information on approved collection systems from our local representative.
By applying this European Directive you will improve the environment and human health!

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ECHNICAL DA A
LHF 405 PIPEWELD LHF 615 PIPEWELD
Maximum load
35 % duty cycle 400 A/36 V 610 A/44 V
60 % duty cycle 310 A/33 V 450 A/38 V
100 % duty cycle 240 A/30 V 345 A/34 V
Setting range 10A/20V--400A/36V 10A/20V--630A/44(49)V
Open circuit volt. 75 V 81 V
Open circuit output
at 400 V 330 W 500 W
Power factor
(max current) 0,80 0,89
Efficiency
(max current) 70 % 74 %
Enclosure class IP 23 IP 23
Application class
Weight 215 kg 303 kg
Dimens. lxwxh 1310/765/705 1310/765/705
Duty cycle
The duty cycle refers to the time as a percentage of a ten--minute period that you can weld at a cer-
tain load without overloading.
Enclosure class
The IP code indicates the enclosure class, i. e. the degree of protection against penetration by solid
objects or water. Equipment marked IP23 is designed for indoor and outdoor use.
Application class
The symbol indicates that the power source is designed for use in areas with increased
electrical hazard.

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WIRING DIAGRAM, LHF 405 PIPEWELD
Component description
WARNING !
S A IC ELEC RICI Y can damage circuit
boards and electronic components.
S
SS
SObserve precautions for handling electrostatic
sensitive devices.
S
SS
SUse proper static--proof bags and boxes.
ESD
B1 Thermal switch: breaks at 68_C, resets at 59_C; fitted on the thyristor
heatsink
B2 Thermal switch: breaks at 160_C
C1 Capacitor 2µF, for cooling fan
C2,C3 Capacitor 0,1µF
H1 Indicating lamp, white
H2 LED, yellow; on when thermal overload is activated, i.e. when one or both
of thermal switcjes B1 and B2 are open
LInductor
LH20/1 Circuit board
M1 Fan
Q01 Mains switch
R01 Potentiometer 2kΩ, for controling the welding current
R03 Potentiometer 10kΩ, for ARC FORCE
R1 Base current resistor, 100Ω
RB hunt, 120mV@400A
S1 elector switch, MMA/Air--Arc Gouging
1 Main transformer
2 Control transformer, supplied at 35V from X45, secondary 19V supplies
circuit board LH20/1
V1,V3,V5 Main diodes
V2,V4,V6 Main thyristors

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V7 Freewheel diode
V8,V9,V10,
V11,V12,V13 Base current diodes
X01 Contact, 6 pole, male
X02 Remote control socket
X10 Mains terminal block
X20 Terminal block
X40 Terminal block
X45 Terminal block
XF20 Contact, 15 pole, female
XF30 Contact, 9 pole, female
XF40 Contact, 12 pole, female
XK1,XK2 Welding current terminals
XM20 Contact, 15 pole, male
XM30 Contact, 9 pole, male
XM40 Contact, 12 pole, male

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LHF 405 PIPEWELD

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WIRING DIAGRAM, LHF 615 PIPEWELD
Component description
WARNING !
S A IC ELEC RICI Y can damage circuit
boards and electronic components.
S
SS
SObserve precautions for handling electrostatic
sensitive devices.
S
SS
SUse proper static--proof bags and boxes.
ESD
B1 Thermal switch: breaks at 68_C, resets at 59_C; fitted on the thyristor
heatsink
B2 Thermal switch: breaks at 160_C
C1 Capacitor 2µF, for cooling fan
C2,C3 Capacitor 0,1µF
H1 Indicating lamp, white
H2 LED, yellow; on when thermal overload is activated, i.e. when one or both
of thermal switcjes B1 and B2 are open
LInductor
LH20/1 Circuit board
M1 Fan
Q01 Mains switch
R01 Potentiometer 2kΩ, for controling the welding current
R03 Potentiometer 10kΩ, for ARC FORCE
R1 Base current resistor, 100Ω
RB hunt, 120mV@400A
S1 elector switch, MMA/Air--Arc Gouging
1 Main transformer
2 Control transformer, supplied at 35V from X45, secondary 19V supplies
circuit board LH20/1
V1,V3,V5 Main diodes
V2,V4,V6 Main thyristors

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V7 Freewheel diode
V8,V9,V10,
V11,V12,V13 Base current diodes
X01 Contact, 6 pole, male
X02 Remote control socket
X10 Mains terminal block
X20 Terminal block
X40 Terminal block
X45 Terminal block
XF20 Contact, 15 pole, female
XF30 Contact, 9 pole, female
XF40 Contact, 12 pole, female
XK1,XK2 Welding current terminals
XM20 Contact, 15 pole, male
XM30 Contact, 9 pole, male
XM40 Contact, 12 pole, male

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LHF 615 PIPEWELD

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DESCRIP ION OF OPERA ION
LH20/1 control board
LH20/1:1 Current setting
The bandgap reference 1,23V diode V2 on LH10/2 PCB makes up a primary
voltage reference for current setting circuit and for digital meter. Current setting
reference voltage 10,7V is derived from 1,23V by the amplifier made of A2a, V30,
C14, R47, R46. The 10,7V voltage establishes reference for local current setting
potentiometer R01 as well as remote control circuitry (X02 socket).

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LH20/1:2 Current and voltage meter
The meter is based upon typical application of ICL7107 integrated circuit.
Reference voltage 1,23V is derived from diode V2. +5V supply consists of C30,
VB1, C31, A10, C32, C33, while --5V supply consists of R1, V1, C34. Measurement
of voltage/current is selected with switch Q4. When Q4 is set to ”A” then gates of
transistors V33 and V34 are on --5V potential, thus voltage signal is shorted to
ground and current signal is transfered to HI input of ICL7107. When Q4 is set to
”V” then gates of transistors V33 and V34 are on +5V potential, thus current signal
is shorted to ground and voltage signal is transfered to HI input of ICL7107. In ”V”
mode transistor V32 is biased via R13 and lits up the decimal point on display.
Potentiometer R6 serves for current measurement calibration while potentiometer
R12 serves for voltage measurement calibration. If needed, current measurement
calibration should be carried out prior to voltage measurement calibration -- all
refered to calibration procedure, see para. 3,4,5.

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LH20/1:3 Functional control circuit AN IS ICK, HO S AR , ARCFORCE
The ANTI TICK function is carried out by the circuit made of the A3 IC and the
transistor V31. If the output voltage falls down below the ANTI TICK threshold,
transistor V31 switches on, consequently switches off the output transistor of the
A3b comparator and the output transistor of the A3a comparator switches on. It
pulls down the current setting signal on the A5b non--inverting input to the minimum
value, and consequently, it limits the output current of the power supply. In MMA
mode operation of ANTI TICK is delayed by C17, R36, R37, R38 and R39. In TIG
mode ANTI TICK operates without any delay while in AAG mode ANTI TICK is
turned off.
The HOT TART function is carried out by the circuit made of the A4 and D1 ICs.
When the welding starts and the arc is stroke, the +15V signal shows up on the
non--inverting input of the A4a. The capacitor C16 is charged via resistor R21 and
the potentiometer of the HOT TART time setting. Time required for charging the
C16 up to +10,7V is the time of the HOT TART. Untill the voltage on the C60 is
lower than 10,7V, there is a high level on the A4b output, and the output transistor
of the D1b connects resistor R27 to the ground. It causes the approximately 35%
voltage rise on the A5a output compared to inverting input thus increasing the
welding current value. In TIG mode the HOT TART is disabled by A6c.
The ARC FORCE function is carried out by the circuit made of the A5a operational
amplifier. As the machine output voltage crosses the ARC FORCE threshold and
keeps decreasing, otput voltage of A5a also decreases. Consequently, the voltage
on the slider of the R03 potentiometer decreases, voltage on the A5a output
increases, thus increasing the welding current. The max current increment caused
by the arc shortening, may be adjusted by means of the R03. In TIG mode the
ARC FORCE is disabled by D2a.

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LH20/1:4 IG mode operation
Tig mode is selected with switch 1 middle position. While TIG mode is active the
ANTI TICK function is enabled, and HOT TART and ARC FORCE functions are
disabled.
In TIG mode transistor V35 is open. Transistors V36, V37, V38 are also open untill
trigger on welding torch is pressed. After trigger is pressed rectifier bridge VB2 is
supplied from transformer T2 winding via voltage divider R60, R61. Consequently
transoptor VC1 is turned on (LED V13 is lit) what makes high level appear on D2b
gate input, as well as transoptor VC2 is turned on through resistor R71. Transoptor
VC2 turns on transistors V36, V37, V38 that control contact arc striking circuit, that
consists of auxiliary bridge and resistor R1 (see the machine diagram).

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LH20/1:5 Wireless remote current control receiver
D4 and D5 ICs form 8 bit memory counter for transmitted value of welding current.
A8 and A9 ICs form D/A converter that converts binary current value to analog
within range of 0--10,7V. Comparator A6a forms detector of signal transmitted by
transmitter N02. Received signal is processed in pulse selector and separator what
serves for RE ET and COUNT pulses identification. COUNT pulse duration is
proportional to welding current value. Gate D3a generates pulse that sets counters
D4 and D5 to zero.
D3b and D3c form flipper that controls pulse counting during current value
transmission. Comparator A6b forms circuit that blocks the receiver during welding.
Potentiometer R95 serves for control voltages calibration. For control voltage
calibration refer to paragraph 4 of ”Testing and calibration procedure”.

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LH20/1:6 Power supply
Power supply is placed on LH20/1 board and consists of positive and negative
voltage sources.
Positive power supply.
+24V supplies thyristor control circuitry;
+15V supplies pulse circuitry on LH20/1 board and supplies function board LH10/2;
+14,5V supplies regulator and current shunt amplifier.
Negative power supply.
--15V supplies operational amplifiers on LH10/2 board;
--14,5V supplies regulator and current shunt amplifier.
LH20/1:7 Regulator and current shunt amplifier
The feedback signal from the current shunt is amplified by the rate of 50 in the
differential amplifier made of the A1 operational amplifier and resistors R12, R13,
R10, R11. Then, through the resistor R14, signal is given to the PI regulator made
of the operational amplifier A2, R17, C7, C8 and voltage limiting diode V13.
The current setting signal is given to the regulator summing point (inverting input of
the A2 OA), via potentiometer R6 and resistor R5 . The power supply may be
disabled by the setting positive voltage through the resistor R15 and thus achieving
the regulator output voltage that blocks thyristors firing circuit.

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LH20/1:8 Synchronisation and thyristors firing
The synchronisation circuit consists of synchronised ramp generators,
comparators, and firing pulse forming circuit.
ignal from the synchronising winding goes via R66(53)(40) and diode limiter made
V26(23)(20) and V27(24)(21) diodes, and then through divider R67(54)(41),
R68(55)(42) to non--inverting input of the comparator A5b(A4b)(A3b). The
R69(56)(43), R70(57)(44), C34(26)(18), R71(58)(45) parts connected to the output
of this comparator make up synchronised ramp generator. The amplitude of the
ramp is adjusted by means of the R71(58)(45) potentiometer. Ramp voltage is
compared with the output voltage of the regulator in comparator A5c(A4c)(A3c).
Thus the firing phase shift is created. The signal from the comparator enables the
pulse generator A8(A7)(A6). Generator output controls the output driver made on
transistors V8(6)(4), V9(7)(5). Driver may be disabled by the positive signal on the
cathode of the V42(41)(40) ) in a case of overtemperature or the lost of
synchronisation. horting the R22 by setting switch ????? to HORT makes the
thyristors driving angle more narrow thus decreases control range of output
voltage.

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LH20/1:9 hermal overload circuit
The circuit co--operates with NC thermal switches connected in series. Opening of
any of them (placed on the transfer or the rectifier) switches the V1 transistor on.
Closed the V1 transistor switches on the H1 indication lamp and disables thyristors
firing.

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LH20/1 -- Components layout

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LH10/2 -- Components layout