Operating Instructions MG3 Digital
How to …?
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2010-08-02
5.3
Conducting Measurements with “Shunt”
Principle of shunt measurement with the MG3Digital
The “shunt measurement” operating mode involves the measurement of a voltage drop
relative to a shunt resistance which, in turn, is series connected relative to a welding
position resistance.
Measurement inputs:
U channel 2
=
shunt voltage (direct)
U channel 1
=
welding position voltage
I channel 1
=
not connected
I channel 2
=
not connected
Representation:
Shunt current
I channel 1 (converted shunt
voltage)
[kA]
Welding position voltage
U channel 1
[V]
Shunt voltage
U channel 2
[V]
I channel 2
empty
The shunt resistance value must be set if the correct shunt current is to be obtained.
The device converts the shunt value into the equivalent current.
The lowest measurable shunt voltage is 50mV for a measuring range of 0.5V U channel 2.
Principle connection to a welding unit
I
-
+
R Shunt
U channel1 = weld spot voltage
Weld Sentry MG3 Digital
weld control
weld spot
U channel 2 = Shunt voltage
Fig. 12: Schematic connection scheme for special “shunt” operating mode
