ESAB Aristo 1000, Calibration instruction Instruction manual / Installation manual / Integrator manual / Service manual
Aristo® 1000
Calibration instruction
Service manual
0464 561 101 GB 20180919
TABLE OF CONTENTS
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.
0464 561 101 © ESAB AB 2018
SCOPE
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.
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© ESAB AB 2018
RACA AND RMS VS. MEAN
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.
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POWER SOURCE CALIBRATION
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
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