RS PRO RM-804, Инструкция по эксплуатации, Страница: 37 / 207

MEASUREMENT
13/10/2016 Version No. 001 35
Zero
0V
V
t
In this mode, RM-805 outputs no
measuring signal on the Source
loop; therefore, the Sense loop
can be used as a voltage meter
which can measure up to +/-10mV
for thermoelectric EMF
measurement. This function is
useful for measuring the Vemf of
thermocouple wires.
A note about Thermoelectric EMF
When making low resistance measurements, thermoelectric
electromotive force (Vemf) can affect measurement accuracy.
Vemf is created at the junction of two dissimilar metals, such as
the contact point of a test lead and the pin of a DUT. Vemf adds a
small but measurable voltage to the measurement.
There are primarily two different methods to compensate for Vemf
in low resistance measurements: Offset Compensation and Vemf
Cancelling. The RM-805 uses Vemf Cancelling with the pulse
drive signal setting.
The Pulse drive mode supplies a positive and a negative
measurement current source.
V I
R
Vemf