Transmille 8000 Series - Manual (Page 37)

8000 SERIES OPERATION MANUAL
TRANSMILLE LTD. Page 36
Using the 8081 – Best measurement practice.
The 8000 series DMM offers several easy to use features to help the user make high accuracy
measurements. The following information gives advice on using these features and how to avoid
common errors.
Nulling or Zero
It is always good measurement practice on DC Voltage, DC Current and Resistance ranges to ‘zero’
the range first before making a reading. By zeroing the range first, any small errors due to thermal
emf voltages and input amplifier input offsets can be removed from the measurement. Thermal and
zero offsets change with time making it necessary to re-zero the system from time to time as
required.
With the 8000 series each range has two zeroes stored, one for the front panel inputs, and one for
the rear panel inputs. It is therefore important to remember to zero both the front and rear inputs in
ratio measurements to obtain accurate comparison measurements whenever both front and rear
inputs are being used.
The 8000 series DMM stores the zero offset in non-volatile memory so the last zero is saved even if
the DMM is switched off.
When autorange is selected all ranges on that function will be zeroed.
Zeroing the Voltage ranges.
System Zero Vs DMM zero -It is often normal to null the DMM by shorting the DMM’s input terminals
together. It may be better short the connecting leads together at the measurement end, to give a
system zero. In this way any thermal EMF voltages from the connecting leads will also be removed
from the measurement.
Diagram : DMM Zero
Diagram : System Zero (Recommended)