Q.series
Gantner Instruments GmbH
147
6 Functional Procedures → Current measurement with an external shunt
6.5 Current measurement with an external shunt
Current measurements are carried out by measuring the voltage
drop across a resistance of known size (shunt resistance). In the
Q.bloxx modules, which are suitable for direct current measure-
ment, this is a resistor of 50 , with which you can measure cur-
rents up to 25 mA (th
e maximum shunt power di
ssipation is lim-
ited to 0.25 W). Higher currents need an external shunt which is
lo
oped into the line to be measured. The power dissipation occur-
ring at the current to be measured must be lower than t
he per-
missible power dissipation of the external shunt. In addition the
voltages produced on
the resistance must not exceed the permis-
sible input voltage on the analog input of
the Q.bloxx module.
Configure the analog input as a voltage input and divide the mea-
sured voltage by R
ext
.
The error in the current measurement using an external shunt
depends on the accuracy of the resistor used.