Improving The Quality Of Measurement Results; 4-Wire Measurement Vs. 2-Wire Measurement - Omicron CT SB2 User Manual

3.7

Improving the quality of measurement results

3.7.1

4-wire measurement vs. 2-wire measurement

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., 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 CT Analyzer are
connected to the test object via separate
clamps.
One clamp is used for each measurement
lead! Correct!
Figure 3-19: Demonstration of 2-wire and 4-wire connection technique
OMICRON
Setup and connection
Do not use!
2-wire connection
Separate measurement leads are used for
the OUTPUT sockets and input SEC of
CT Analyzer, but the measurement leads
are connected to the test object via one
common clamp.
Two measurement leads use one single
clamp! Do not use!
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