PSM3750 Quick User Guide
Page 58
Shunt Selection
The different shunts built into the IAI2 allow the test conditions to be modified to
optimise the measurement accuracy. In general a higher value shunt increases
the magnitude of the current signal at the A/D and decreases the magnitude of
the voltage signal across the component; conversely a lower value shunt
decreases the magnitude of the current signal at the A/D and increases the
magnitude of the voltage signal.
Optimum accuracy is when the voltage and current signals are approximately
equal (the impedance of the shunt is approximately the same as the impedance
of the DUT), but good results can be obtained with impedances within a factor of
100 of the shunt value.
It is necessary to take great care in order to achieve the best accuracy of
measurement. The leads of the component must be scrupulously clean and for
repeatability the component must be connected in exactly the same position.
Slight variations in connection can result in significantly different measured
values, especially at high frequencies.
In general the “very high” shunt should only be used for high impedance
measurements (>1MΩ) at low frequencies (<1kHz)
.
The “low” shunt is used with higher current testing of low impedances as it
includes a current boosting amplifier that can deliver up to 0.5Arms.
Warning: High Voltages can be generated when the current flowing
through an inductive component is interrupted. So turn the output OFF
before disconnecting an inductive or unknown component