Brochure/Catalogue

Glossary
Switching threshold The switch-on or switch-off point.
T
Temperature classes Explosion-protected equipment that is to be installed into the Ex zone is
subdivided into six temperature classes (T1 to T6).
These temperature classes dene the maximum surface temperature permitted
for the equipment. The denition is based on an ambient temperature of +40 °C.
This temperature may not be exceeded on any part of the equipment at any
point in time. In all cases, the maximum surface temperature must be lower than
the ignition temperature of the surrounding medium. The requirements placed
on the equipment become stricter from class T1 to T6.
Temperature coefcient The temperature coefcient describes the relative change of a physical variable
based on the temperature change relative to a reference temperature (room
temperature). It directly inuences the precision of an analogue signal converter.
The coefcient is specied in ppm/K of the corresponding measuring range end
value.
Thermocouple A thermocouple is a component made of two different materials which are
connected to each other at one end. An electrical voltage is created (based on
the principle of the Seebeck effect) along a wire that connects the unattached
ends when there is a temperature differential.
The juncture point and the unattached ends must have different temperatures
for a voltage to be generated.
The following thermocouples are used for industrial applications:
Thermal pair Short name Type Temperature range in °C
Nickel/Chrome-Nickel/Al NiCr-Ni/Al K -200 ... +1372
Iron-constantan Fe-CuNi J -200 ... +1200
Copper-constantan Cu-CuNi T -200 ... +400
Nickel/Chrome constantan NiCr-CuNi E -200 ... +1000
Platinum/10 % Rhodium-Platinum Pt10Rh-Pt S –50 ... +1760
Platinum/13 % Rhodium-Platinum Pt13Rh-Pt R -50 ... +1760
Nickel/Chrome-Nickel/Magnesium NiCr-NiMg N -200 ... +1300
Platinum/30 % Rhodium - Platinum/6 % Rhodium Pt30Rh - Pt6Rh B 0 ... +1820
Temperature in °C
Voltage in uV
6000
5000
4000
3000
2000
1000
0
-1000
-400 -200 0 200 400 600 800 1000 1200 1400
W
Technical appendix/Glossary
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