Service manual
0464 561 101 GB 20180919
Aristo® 1000
Calibration instruction
TABLE OF CONTENTS
0464 561 101 © ESAB AB 2018
SCOPE...................................................................................................... 3
RACA AND RMS VS. MEAN .................................................................... 4
POWER SOURCE CALIBRATION ........................................................... 5
Calibration setup .................................................................................... 5
Connection ........................................................................................... 5
Connection of load resistors.............................................................. 6
Connection of RACA ......................................................................... 6
Calibration measurement ...................................................................... 8
Additional information ........................................................................... 8
WIRE FEED SPEED CALIBRATION........................................................ 9
TRAVEL SPEED CALIBRATION.............................................................. 10
TOLERANCES.......................................................................................... 11
REFERENCES.......................................................................................... 12
ORDERING NUMBERS............................................................................ 13
Rights reserved to alter specifications without notice.
SCOPE
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SCOPE
Validation versus calibration:
The standard EN50504 requires validation of the equipment. The reason is that a welding
equipment is not just device where you can see the relation between a setting value and an
output value as a control value and a real value between which there are a deviation that is
the inaccuracy. The values displayed in a measure devices can however be handled in this
way. Therefore only measure devices in the equipment can easily be calibrated but a test of
the device shall include the whole welding equipment. The solution to this in the standard is
to choose the word validation when a calibration requirement would be too hard for the
actors to be able to know how it should be done on all types of machines. This instruction
however includes a process that also covers deviation in accuracy in how the weld process
control handles voltage and current, not only the accuracy of measure devices. In this way
we exceed the requirement in the standard and therefore call this instruction calibration
instruction, not validation instruction.
This calibration instruction should be used:
• When the equipment is calibrated according to EN50504,
• If the equipment is calibrated according to any other calibration standard,
• If the equipment is checked without referring to any specific standard.
The calibration is to measure and document accuracy of different parameters. The result can
be that the equipment can benefit from having different trimming operations done. Such
trimming operations are not included in the calibration procedure, they are service operations
that very well can be executed in conjunction with the calibration. Be aware of that EN50504
requires that a calibration shall be executed after a service operation is done on the
equipment. This means that if trimming is done it should be finalized and then shall the
calibration be carried out afterwards.
RACA AND RMS VS. MEAN
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RACA AND RMS VS. MEAN
The ESAB power sources are internally using a circuit that will measure the rectified
arithmetic mean value of any AC signal (referred to as mean value in this document). This
has been the case for many years and has its roots in the early days when RMS
measurement was very complex and was often not cost effective. Old RMS indicating
instruments where basically measuring the arithmetic mean value and multiplying it by a
constant to get to a RMS value. This was only valid for pure sinusoidal waveforms as the
correction factor is different for different waveforms. The welding current and voltage cannot
be considered to be sinusoidal waveforms in most cases. It has been shown that the mean
value is better corresponding to the actual heat input to the base material (Ref 3, M.R.
Bosworth). To have control of the heat input in the base material is one of the most important
factors to consider when welding an object. For the above reasons, ESAB is using mean
value to represent the set and actual values in the welding system. To use the right
measuring equipment when measuring the output voltage and current of the power source is
extremely important. Most RMS multimeters have a high pass filter that filters out the DC
component when they are set to measure an AC signal. This creates an issue since the AC
weld process by nature will contain a DC component. This is due to the melt off rate of the
wire being different on the positive and negative side. It gets even worse when such an
instrument is used to measure the AC output of the Aristo1000 when the AC balance is
used. Measuring on an asymmetrical AC signal (signal containing both DC and AC
components), like the AC weld process, is very difficult with today’s multimeters since most of
them are designed to work with pure AC wave forms and some are even limited to sinusoidal
waveforms.
Since it is very hard to find multimeters that measures the mean value of an asymmetrical
signal in a correct way (mean value of the DC and AC component at the same time) ESAB
has created the RACA. The RACA is a box that converts an asymmetrical signal, both
voltage and current, into a DC voltage that is directly proportional to the mean value of the
asymmetrical signal. This DC value can be measured correctly by any DC multimeter. The
DC voltage measured at the output of the RACA is multiplied by a factor 10 to get the actual
value. Like any measuring equipment, the RACA can and needs to be calibrated on a regular
basis for correct function.
RACA calibration kit is calibrated as a system and components cannot be interchanged
between different kits.
POWER SOURCE CALIBRATION
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POWER SOURCE CALIBRATION
A successful calibration according to this specification is valid for all methods and settings
available in the machine. If a limited calibration is done the calibration is valid in the same
limited current region in other methods than SAW.
This calibration instruction is valid for ARISTO1000AC/DC but the RACA kit can also be
used for other ESAB power sources, see connection instructions in the service manual for
each power source.
Calibration setup
Connection
Connection for calibration can be made with a minimum of changes in a weld installation or
with a separate power source disconnected from its ordinary weld circuit. It is not necessary
to disconnect the ordinary weld cable and return cable connections. The load connection
cable area is not critical for the calibration result.
When calibrating in an existing complete installation connect the load between the welding
head and a suitable work piece connection point.
Figure 1. Calibration setup
1. Welding head 8. Welding cable
2. Control unit 9. Measurement speed
3. Control cable 10. Motor cable
4. Welding power source 11. Measurement welding voltage
5. Return cable 12. Resistance load
6. Measurement cable workpiece 13. Twisted pair
7. Workpiece
POWER SOURCE CALIBRATION
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Connection of load resistors
Use a load resistor bank, for example 2 pcs Checkmaster 9000 (ESAB part number
0740505881) connected in parallel, see Figure 2. Connect the load resistors with a proper
cable area to be enough also for the maximum current. If multiple load bank units are used
try to have the same settings on all in order to have the power dissipation almost equal in
between. This is absolutely necessary on high current since one of them might be
overloaded otherwise.
Figure 2. Load resistor connection
Connection of RACA
• Connect the voltage inputs to RACA to the two voltage sense connectors, workpiece
(black) and welding head (red) on the power source. (Refer to voltage feedback inputs
on the power source). Use twisted pair cable.
1. Workpiece (black) 2. Welding head (red)
POWER SOURCE CALIBRATION
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• Keep the voltage feedback arrangement as it is intended to be in welding but take the
opportunity to check that it is in agreement with the recommendations in the manual of
the equipment.
• Put the current sensor on any suitable place in the load current circuit and connect it to
RACA. Observe that the current sensor and the RACA unit is paired. See that RACA is
always used with its own current sensor.
• Put RACA on DC when the power source is in DC mode and in AC when the power
source is in AC mode.
• Connect two good quality multimeters to the outputs of RACA and put both of them on
a measure range that covers 0 to 10 volts. Their accuracy shall be 0.1 % of the
measured value in the range they are used.
• After power up of RACA but before power up of the power source, do an offset
adjustment for current sensor signal by adjusting to 0 on the knob.
• Switch on the power source before calibration measurements.
Figure 3. RACA connections
1. AC > DC / DC switch 7. Current measurement return
2. Power input 8. Offset adjustment
3. Power indicator 9. Current sensor connection
4. Voltage 0.1 / Vavg 10. Workpiece
5. Voltage measurement return 11. Welding head
6. Current 7mV / Aavg
POWER SOURCE CALIBRATION
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Calibration measurement
• Set the following parameters on the PEK:
Method: SAW, DC
Control mode: CW for "Current test"
CC for "Voltage test"
Weld Speed: Set travel motion to external axis by defining a soft button and
activate it. In this way can the machine run for a longer time
without interrupts from travel system.
Then set the working point according to the table by setting voltage on the PEK and
adjust the current by changing the load bank. Release the wire feeding drive rolls.
• Start on the PEK and note measure values in the protocol template. Observed values in
the system is what is shown on the PEK. Run the working points in the current test
table in specified order and then in reversed order.
• Change setting to CC and run the working points in the voltage test table.
• Change setting to AC and repeat the steps above.
Current test Voltage test
Measurement Voltage Current Measurement Voltage Current
1 28V 200A 1 10V 400A
2 36V 400A 2 20V 400A
3 44V 600A 3 30V 400A
4 44V 800A 4 40V 400A
5 44V 1000A 5 50V 400A
Additional information
• A limited calibration that is limited in load range can be done according to EN 50504. In
that case the calibration/validation for all methods are only up to the highest current
value that it is calibrated at.
• Voltages in the "Current test" is from the SAW ISO line, U = Min ((20 + 0,04 × I), 44)
• The values in the table must not be met exactly. Working points will have a temperature
drift from the change of resistor value in the load. Important is that observed value from
PEK and real value reading from the DVMMs are done simultaneously so the influence
from temperature drift is limited.
• Calibration of the RACA kit:
The RACA box and the current sensor has to be calibrated together. If changing either
of them a new calibration with both items together has to be done.
WIRE FEED SPEED CALIBRATION
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WIRE FEED SPEED CALIBRATION
Calibration shall be made by comparison between the set value and the speed measured by
the calibration equipment. Calibrated instruments should be used.
The wire feed speed should be measured at two levels:
• 60-80% of the equipment wire feed speed interval
• Below 30% of the equipment wire feed speed interval
Wire feed speed should be measured with tachometer.
To ensure that the wire feed mechanism function the resistive load arrangement used in the
voltage and current calibration measurements should remain connected.
Figure 4. Wire feed speed calibration setup
1. Welding head 7. Workpiece
2. Control unit 8. Welding cable
3. Control cable 9. Measurement speed
4. Welding power source 10. Motor cable
5. Return cable 11. Measurement welding voltage
6. Measurement cable workpiece
TRAVEL SPEED CALIBRATION
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TRAVEL SPEED CALIBRATION
Calibration shall be made by comparison between the set value and the speed measured by
the calibration equipment. Calibrated instruments should be used.
The travel speed should be measured at two levels:
• 60-80% of the equipment travel speed interval
• Below 30% of the equipment travel speed interval
Travel speed should be measured were suitable on the actual movable part of the equipment
setup.
The measurement should be performed with tachometer or scale and timer.
TOLERANCES
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TOLERANCES
Specified accuracy of this equipment is specified in table below.
Aristo1000
Quantity Inaccuracy
CurrentDC ± (1.0% of actual value + 2A of absolute value)
CurrentAC ± (1.0% of actual value + 2A of absolute value)
VoltageDC ± (1.0% of actual value + 0.3A of absolute value)
VoltageAC ± (1.0% of actual value + 0.3A of absolute value)
Wire feed speed ± (2.5% of actual value + 1cm of absolute value)
Travel speed ± (2.5% of actual value + 1cm of absolute value)
REFERENCES
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REFERENCES
[1] IEC60974-1 Arc welding equipment - Part 1: Welding power sources
[2] EN50504 Validation of Arc Welding Equipment
[3] Effective Heat Input in Pulsed Current Gas Metal Arc Welding with Solid Wire
Electrodes - M.R Bosworth (www.awg.org)
[4] Multimeters: Measurement deviation -
http://meettechniek.info/multimeteravo/measurement-deviation.html
ORDERING NUMBERS
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ORDERING NUMBERS
Ordering number Denomination Type Notes
0464 561 880 RACA calibration kit 2000A
Technical documentation is available on the Internet at: www.esab.com
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