© 2018 imc Test & Measurement GmbH
imc C-SERIES - Manual, Version 4 R 3 - 2018-10-19
122 Device description
5.8.4.2.1 PT100 in 4-wire configuration
The PT100 is supplied by two lines. The other two serve as Sense-
leads. By using the Sense-leads, the voltage at the resistor itself
can be determined precisely. The voltage drop along the
conducting cable thus does not cause any measurement error.
The 4-wire configuration is the most precise way to measure with
a PT100. The module performs a genuine differential
measurement.
PT100 in 4-wire configuration is not possible for
·
an (optional) sensor supply with ±15 V.
·
the former C-70xx equipped with a 350 Ω quarter bridge
completion.
5.8.4.2.2 PT100 in 2-wire configuration
Use the software to set a PT100 4-wire configuration, because the connection is made in the same way
as for the 4-wire configuration. The difference is that +IN/-SENSE and -IN/-VB must be jumpered inside
the connector. Note that the total cable resistance contributes to measurement error, and that this
method is the most imprecise and not to be recommended.
5.8.4.2.3 PT100 in 3-wire configuration
The PT100 is supplied by two lines. The other one serve as SENSE
lead. By using the Sense-lead, the voltage at the resistor itself can
be determined precisely. The voltage drop along the conducting
cable thus does not cause any measurement error.
It is important, that the connection between +IN to -SENSE and -IN
to -VB is made directly at the module.
3-wire configuration is not as precise as 4-wire configuration.
When in doubt, 4-wire configuration is preferable.
PT100 in 3-wire configuration is not possible for:
·
an (optional) sensor supply with ±15 V.
·
the former C-70xx equipped with a 350 Ω quarter bridge
completion.
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