Elettro 471 User manual

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PLASMA 56 COMPRESSOR INVERTER
POWER SOURCE art. 471 and art.471.48
SERVICE MANUAL
art.471 (Fig.1 3.2.1) art.471.48 (Fig.2 3.2.1)

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CONTENTS
1- GENERAL INFORMATION .............................................................................................................. 3
1.1 - Introduction...................................................................................................................................... 3
1.2 - General service policy....................................................................................................................... 3
1.3 - Safety information. ........................................................................................................................... 3
1.4 - Electromagneticcompatibility. .......................................................................................................... 3
2- SYSTEM DESCRIPTION................................................................................................................... 4
2.1 - Introduction...................................................................................................................................... 4
2.2 - Technicalspecifications. ................................................................................................................... 4
2.3 - Description of power source art. 471................................................................................................. 4
3- MAINTENANCE ............................................................................................................................... 7
3.1 - Periodic inspection, cleaning............................................................................................................. 7
3.2 - Operating sequence (fig. 3.2.1).......................................................................................................... 7
3.2.1 - Power source commands and signals............................................................................................... 8
3.2.2 - Power source operation .................................................................................................................. 9
3.3 - Troubleshooting................................................................................................................................ 11
3.3.1 - The power source does not start, led (A) off.................................................................................... 11
3.3.2 - Power source powered, led (A) lit, fan (9)stopped. ......................................................................... 13
3.3.3 - Power source powered, the signals do not indicate correct values. ................................................... 13
3.3.4 - The start button produces no effect.................................................................................................. 14
3.3.5 - No gas flows from the torch............................................................................................................ 15
3.3.6 - Gas flows from the torch, the pilot arc does not light (contact tip voltage missing) .......................... 16
3.3.7 - In open circuit operation, the output voltage is not regular............................................................... 17
3.3.8 - Irregular pilot arc starts, unstable pilotarc....................................................................................... 19
3.3.9 - Transfer arc does not take place or is too weak for cutting ............................................................... 21
3.4 - Alarm signals.................................................................................................................................... 23
3.4.1 - Led (C) lit = temperature outside limits........................................................................................... 23
3.4.2 - Led (D) lit = low gas pressure......................................................................................................... 23
3.4.3 - Led (B) steadily lit = power sourceblocked .................................................................................... 24
4- COMPONENTS LIST......................................................................................................................... 25
4.1 - Power source art. 471........................................................................................................................ 25
4.2 - Table of components......................................................................................................................... 25
4.3 - List of spare parts.............................................................................................................................. 25
5- ELECTRICAL DIAGRAMS ............................................................................................................... 26
5.1 - Power source art. 471........................................................................................................................ 26
5.2 - Waveforms. ...................................................................................................................................... 26
5.2.1 - Open-circuit output voltage, interrupted after approximately 300 msec. for missing pilot arc current
(par. 3.3.6, 3.3.8) .............................................................................................................................26
5.2.2 - Open-circuit rectifier output voltage, interrupted after approximately 300 msec., for missing pilot
arc current (par. 3.3.7). ....................................................................................................................26
5.2.3 - Open-circuit inverter output voltage, interrupted after approximately 300 msec. for missing pilot
arc current (par. 3.3.7). ....................................................................................................................27
5.2.4 - Pilot arc current signal for its maximum time, approximately 2 sec., with the torch free in the air
and thus without transfer arc (par. 3.3.8)...........................................................................................27
5.3 - Filter board (10)................................................................................................................................ 28
5.4 - Igbt board (46).................................................................................................................................. 29
5.5 - Secondary board (70) ........................................................................................................................ 30
5.6 - Panel board (60) ............................................................................................................................... 31
5.7 - Control board (63) ............................................................................................................................ 32

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1 - GENERAL INFORMATION
1.1 - Introduction.
The purpose of this manual is to train personnel assigned to carry out maintenance on the
power source art. 471 for plasma cutting systems.
The power source exists in two variants:
•art. 471 (3.2.1-Fig.1)
•art. 471.48 (3.2.1-Fig.2)
Art. 471 is equipped with a 4 m, ECF-71 torch with direct connection consisting of:
•power source start contact
•negative potential (-) eyelet
•Gas hose
Art. 471.48 is equipped with 8-pin Easy Fit fixed adapter (48), where:
•1-2 pin torch button
•7-8 pin torch recognition
•4-5 pin pilot arc current
1.2 - General service policy.
It is the responsibility of the customer and/or operator to use the equipment appropriately, in
accordance with the instructions in the Instruction Manual, as well as to maintain the equipment
and related accessories in good working condition, in compliance with the instructions provided
in the Service Manual.
Any internal inspection or repairs must be carried out by qualified personnel who are
responsible for any intervention on the equipment.
It is forbidden to attempt to repair damaged electronic boards or modules; replace them with
original ELETTRO CF s.r.l. spare parts.
1.3 - Safety information.
The safety notes provided in this manual are an integral part of those given in the Instruction
Manual. Therefore, before working on the machine, please read the paragraph on safety
instructions in the aforementioned manual.
Always disconnect the power cord from the mains, and wait for the internal capacitors to
discharge (1 minute) before accessing the interior of theequipment.
Some internal parts, such as terminals and swirl rings, may be connected to mains or
otherwise hazardous potentials. It is therefore forbidden to work with the safety guards removed
from the machine unless strictly necessary. In this case, take special precautions such as wearing
insulating gloves and footwear, and working in a perfectly dry environment with dryclothing.
1.4 - Electromagnetic compatibility.
Please read and observe the instructions provided in the paragraph “Electromagnetic
compatibility” of the Instruction Manual.

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2 - SYSTEM DESCRIPTION
2.1 - Introduction.
The PLASMA 56 COMPRESSOR is a plasma arc system for cutting electrically conductive
materials.
It is made up of an electronic power source (art. 471 or art. 471.48) with three-phase
compressor and a set of accessories for use in manual applications.
The power source is controlled by microprocessor circuits, which manage the operative
functions of the cutting system and operator interface.
2.2 - Technical specifications.
To verify the technical specifications, see the machine plate, Instruction Manual, and Sales
Catalogue.
2.3 - Description of power source art. 471
Art. 471 is a controlled current direct current power source composed of a three-phase
compressor and made up of a three-phase rectifier bridge, a DC/AC converter (inverter) and an
additional rectifier bridge.
It may be powered at 400 Vac.
Referring to the electrical diagram, you can identify the main blocks that make up the power
source.
The main switch (58) powers the filter board (10) which contains the filter to reduce
conducted interferences reflected in the mains and the compressor (4) through the remote-control
switch (6).
The integrated circuit U1 on igbt board (46) generates the 13.8 Vdc service voltage to
power the electronic boards; the transformer TF1, together with the rectifier D1, generates the
isolated supply voltage for the torch start button circuit, on the panel board (60).
The relay K2 drives the coil of remote-control switch (6) based on the commands received
from the control board (63). The remote-control switch (6) brings power to the compressor (4)
that produces the compressed air required to power the torch.
The coil of remote-control switch (6), as well as the fans (9) are always powered at 230
Vac.
The rectifier bridge (13) is connected to the output of the filter board (10), and rectifies the
mains voltage at the filter board (10) output into direct current equivalent to 560 Vdc,
approximately. This voltage, applied to the inverter, made up of the igbt board (46) and the igbt
modules (44), is converted once again into square-wave alternating voltage, suitable for
powering the power transformer(53).
The 4 resistors (42) connected to J2 of igbt board (46) limit the current in the electrolytic
capacitors on the igbt board (46), which in turn level the direct current rectified by the bridge
(13).
Their interruption makes these capacitors isolated and useless, while a short-circuit will
damage the capacitors.
The igbt board (46) contains the TA to detect the current at the primary circuit of the
transformer (53). Its signal is used by the control board (63) to adjust the pilot arc and cutting
current.
The secondary transformer circuit (53) is made up of 4 separate identical windings, connected
to a shared point on the terminal S2-S5 of the secondary board (70), to form a dual central socket
winding. The other ends of the 4 windings are connected to terminals of the diode (68) to rectify
the alternating current generated by the inverter (46). Inserted between the + output of the diode
and the + terminal of the secondary board (70) (terminal L2), the inductor (52) is connected to

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level the power source output current.
In this way the direct current voltage at the output of the secondary board (70) and present at
its terminals (-) and (+) is available for the power source output.
The resistor (72) connected to CN2 of secondary board (70) helps balance the currents
between the secondary windings of the transformer (53).
If interrupted, it may cause unstable operation both in the pilot arc and while cutting, while a
short-circuit will definitely damage the secondary board (70).
The secondary board (70) includes the nozzle relays RL1 and RL3 to enable the nozzle
voltage, and the solenoid with reed bulb RL2 to detect the cutting current on the earth conductor
of the power source (workpiece potential).
When the two relays are in resting condition (thus with power source on or with pilot arc),
they provide on terminal F1, corresponding to the torch nozzle terminal, the same voltage present
on terminal L2 of the secondary board (70), corresponding to the + output of the power source.
When the torch with pilot arc lit is moved close to the workpiece, the solenoid with reed bulb
detects the current passing through the earth conductor of the power source, and commands the
switch from pilot arc to transfer arc, by means of the nozzle relays RL1 and RL3, which cut off
voltage on the nozzle terminal F1.
The reed RL2 simultaneously sends the same signal to the control board (63), which starts
the transfer arc working mode(cutting).
The secondary board (70) includes the Hall-effect current transducer to detect the cutting
current. Its signal is used by the control board (63) to limit the maximum output current of the
power source.
The cutting current is adjusted by the inverter, made up of the igbt board (46) and igbt
modules (44), appropriately controlled by the control board (63).
The control board (63) contains the main power source microprocessor, and supervises
management of the other boards.
It adjusts the cutting current, generates the PWM signal to be sent to the igbt (44) through
the isolated drive circuits built into the same board, and also handles diagnostics of the power
source, managing the control panel consisting of the panel board(60).
Given the particular configuration of the inverter (control board (63) with built-in drive
circuits connected directly to the igbt (44)), quite these drive circuits suffer damage
following an igbt (44) fault. For this reason we recommend simultaneously replacing the
control board (63) along with the igbt (44). Otherwise, the new igbt controlled by defective
drive circuits would again be damaged. Similarly, should it be necessary to replace the
control board (63) following a fault in the igbt drive circuits, we recommend that you also
replace the igbt (44) at the same time.
The panel board (60), mounted on the front panel, acts both as a control panel for the power
source, and as an input and conditioning interface for those signals especially affected by
disturbances because they arrive from critical areas of the system.
These signals include:
−Start power source,
−Torch type recognition (only art. 471.48)

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The panel board (60) contains the following control elements:
−Potentiometer to adjust the cutting current.
−A set of leds to indicate the operating status.
The signals processed by the electronic boards and present at their connectors are listed in the
table in chapter five of thismanual.

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3 - MAINTENANCE
WARNINGS
ANY INTERNAL INSPECTIONS OR REPAIRS MUST BE CARRIED OUT BYQUALIFIED
PERSONNEL.
BEFORE BEGINNING MAINTENANCE OPERATIONS, UNPLUG THE POWER SOURCE
FROM THE MAINS AND WAIT FOR THE INTERNAL CAPACITORS TO DISCHARGE (1
MINUTE).
3.1 - Periodic inspection, cleaning.
Periodically open the power source grids and check inside the aeration tunnel.
Remove any dirt or dust to ensure smooth air flow, and thus adequate cooling of the internal
parts of the power source.
Check the condition of the output terminals, output and power supply cables of the power
source; replace if damaged.
Check the condition of the internal power connections and connectors on the electronic
boards; if you find “loose” connections, tighten or replace theconnectors.
3.2 - Operating sequence (fig. 3.2.1).
The following sequence represents correct functioning of the machine. It may be used as a
guiding procedure fortroubleshooting.
It must be carried out after each repair without anyerrors.

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3.2.1 - Power source commands and signals.
Fig.1 (Art.471)
Fig.2 (Art.471.48)

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3.2.2 - Power source operation.
NOTE
 Operations marked with this symbol refer to operator actions.
♦The operations marked with this symbol refer to machine responses that must occur following
an operator action.
 System shut off and unplugged from the mains.
 Connect the torch to the power source (only art. 471.48)
 Connect the cable of the positive pole of the power source to the workpiece.
 Connect the power source to the mains.
 Close the switch (O) on the power source.
♦System powered, led (A) lit, fan running.
♦On front panel, leds (C) and (D) off; led (B) lit for the first 5 seconds (mains
voltage analysis and selection), then off.
Correct? NO (see 3.3.1, 3.3.2, 3.3.3).
YES
WARNING
DURING THE FOLLOWING TESTS, DO NOT POINT THE TORCH AT PEOPLEOR
PARTS OF THE BODY, BUT ALWAYS TOWARDS AN OPEN SPACE OR THE
WORKPIECE.
 Press the torch start button and hold it down.
♦Gas flows from the torch a n d the pilot arc starts for the maximum pilot arc time
(2 sec.). The gas continues to flow for approximately another 100 sec. after the
start button is released (post-gas time).
Correct? NO (see 3.3.4, 3.3.5, 3.3.6, 3.3.7, 3.3.8).
YES

 With pilot arc lit, place the torch near the workpiece.
♦Begin cutting. Adjust the knob (F) to the current level suited to the kind of
cutting.

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Correct?
YES
NO (see 3.3.9).
 Release the torch start button.
♦The arc shuts off immediately. The gas continues to flow for the post-gas time
(approximately 100 seconds after the start button is released) to cool the torch.
Correct? NO (see 3.3.5),
YES
REGULAR OPERATION.