14.1 Outline of External Resistance Calibration
14-1
HW0480311
HW0480311
14
Calibration for External Resistance
The MOTOWELD-EH500 has a function to compensate for the voltage drop due to cable
extension, etc. This function is effective only when short-circuit welding is selected.
14.1
Outline of External Resistance Calibration
Since the negative (-) side power cable and jig stand connecting the welding source and the
base metal to be welded contain electric resistance, voltage applied between the torch and
the base metal drops by several volts compared with the voltage output from the welding
source.
The MOTOWELD-EH500 can automatically compensate for
the voltage drop due to external
resistance by measureing the electric resistance of the connected power cable or jig stand to
set the resistance value.
By calibrating the external resistance, the same actual welding voltage can be obtained with
the same synergic voltage command even in a station having different power cable length or
jig stand with different electric resistance. Therefore, the database incorporated into the
MOTOWELD-EH500 can be effectively used.
Fig. 22 Voltage Drop by External Resistance
Actual welding voltage Ea = (Welder output voltage Em)
−
(Welding current
I
)
×
(External resistance R)
External resistance R
Actual welding voltage Ea
Welder output voltage Em
Negative (-) side power cable
Voltage detection cable
Welding current
I
Positive (+) side power cable
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