WIKA TR10-A - Handbuch (Seite 10)

3345267.12 01/2014 GB/D
10 WIKA operating instructions RTD and TC, intrinsically safe designs (Ex i)
GB
Explanation of symbols
Before mounting and commissioning the instrument, ensure you read the
operating instructions!
CE, Communauté Européenne
Instruments bearing this mark comply with the relevant European directives.
ATEX European Explosion Protection Directive
(Atmosphère = AT, explosible = EX)
Instruments bearing this mark comply with the requirements of the European
Directive 94/9/EC (ATEX) on explosion protection.
3. Specifications
3.1 Resistance thermometer
Sensor connection method
■ 2-wire
■ 3-wire
■ 4-wire
Limiting error of the sensor per DIN EN 60751
■ Class B
■ Class A
■ Class AA
The combination of a 2-wire connection with class A or class AA is not permissible, since the
lead resistance of the measuring insert negates the higher sensor accuracy.
Basic values and limiting errors
Basic values and limiting errors for the platinum measurement resistances are laid down in
DIN EN 60751.
The nominal value of Pt100 sensors is 100 Ω at 0 °C.
The temperature coefficient α can be stated simply to be between 0 °C and 100 °C with:
α = 3.85 ∙ 10 -3 °C -1
The relationship between temperature and electrical resistance is described by polynomialss,
which are also defined in DIN EN 60751. Moreover, this standard specifies the basic values in °C
steps in tabular form.
2. Safety / 3. Specifications