Improving The Quality Of Measurement Results; 4-Wire Measurement Vs. 2-Wire Measurement - Omicron Lab CT Analyzer User Manual

CT Analyzer User Manual
2.7

Improving the Quality of Measurement Results

2.7.1

4-Wire Measurement vs. 2-Wire Measurement

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If the secondary side of the test object does not provide screw terminals for
connecting the delivered terminal adapters or banana sockets to insert the
measurement leads directly, and it is therefore necessary to use clamps (e.g.
crocodile clamps or Kelvin clamps) for the connection of the measurement
leads, always use the 4-wire connection technique as described below.
Otherwise, the possibly existing contact resistance of the clamps could
affect the measurement results, i.e., the CT Analyzer possibly delivers
incorrect measurement results.
Both connection techniques are shown in the following figure.
OK
4-wire connection
The measurement leads from the
"Output" sockets and input "Sec" of
the CT Analyzer are connected to the
test object via separate clamps.
One clamp is used for each
measurement lead! Correct!
Figure 2-19 Demonstration of 2-wire and 4-wire connection technique
Do not use!
2-wire connection
Separate measurement leads are
used for the "Output" sockets and
input "Sec" of the CT Analyzer, but
the measurement leads are
connected to the test object via a
common clamp.
Two measurement leads use one
single clamp! Do not use!