82.031.0101.0 WIELAND ELECTRIC, 82.031.0101.0 Datasheet - Page 500

• Manufacturer Part Number: 82.031.0101.0
• Description: COUPLING MODULE
• Manufacturer: WIELAND ELECTRIC

Specifications of 82.031.0101.0

• Connector Type: Modular
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

dipos
The influence of the insulation
resistance on the temperature
measurement
The design of RTD sensors can lead to
measuring errors. This is independent of
the type and manufacturer. One of the
most frequent sources of error is the
insulation in the sensor. If it is not
sufficient, it can seriously impair the
measurement. Causes of a low-resistance
insulation can be heat, vibration, physical,
chemical or radioactive influences.
Measurement with Pt100
The Pt100 element is a low-resistance
sensor. If the insulation resistance is too
low, the measurement is influenced.
The diagram shows the electrical circuit
diagram of the Pt100, connected to a RTD
signal conditioner. Apart from the current
flowing over the sensor, a minor current
normally also flows over the insulation
resistance R
resistance falls, the proportion that flows
over the insulation resistance also
naturally rises. Due to the constant
current that is supplied by the RTD signal
conditioner, the voltage drop is also
reduced. This produces a measured
temperature value that is too low,
regardless of whether the RTD signal
conditioner is operated with or without
electrical isolation. During operation
without electrical isolation, leakage
current can however be caused between
the sensor and earth if the insulation
resistance is too low. This also leads to a
lower temperature display. An isolated
RTD signal conditioner rules this out.
498
Analog measurement technology
RTD (Pt100)/TC
dipos
ISO1
. If the insulation
Thermal transformer module
Measurement via thermocouples
Limited by the principle of the
thermocouples, other errors arise due to
the extremely small insulation resistances.
The EMF (electromotive force) of
thermocouples is not particularly
susceptible in the event of a low
insulation resistance. The problem lies in
the fact that a new measuring point
occurs due to the low insulation
resistance. If this measuring point is found
in the vicinity of the existing point, the
influence is negligible. However, if it is
located where there is a temperature
differential to the measuring point, the
measuring error can be considerable. As a
result, it is almost impossible to diagnose
a break in the sensor.
The thermocouple signal conditioner
dipos
and carries out measurements and checks
beyond the standard. One of these checks
is the display of the insulation resistance
of the connected sensor. This function is
called “Smart Sense”. To implement this
function, the sensor must be provided
with an additional conductor. In the case
of TC sensors, a special sensor is required
which contains an additional conductor
PROG
is microprocessor-controlled
Does not flow through the Pt100
Thermal transformer module
No electrical isolation
Thermal transformer
Thermal transformer
that is not used for temperature
measurement.
Under certain conditions, it is possible to
use the shield of the cable as the
following diagram indicates:
An excessively low insulation resistance is
indicated with a flashing LED at the
module and the output signal is set to a
preselected value. Smart sense not only
monitors the sensor state but also the
connections from the sensor to the
thermal transformer module. This
guarantees the complete control of the
measuring point up to the thermocouple
signal conditioner.
Metal contact cable
Separation transformer
Smart Sense