Types and properties of sensors of temperature
   
Basic types of professional temperature sensors.
 

Thermocouple sensors (TC) are produced by connecting two different materials (metals). By heating of this connection is generated on the ends of the thermocouple thermoelectric voltage whose values are on the order of a few tens mV. The range of output voltage and its linearity is given by materials, which the sensor is made from. Moreover by these materials is also determined the sensor usability in practice. The connection between the sensor and the controller shall be made by using compensation or thermocouple line , which is necessary and no common copper wire can be used!

Resistance sensors - resistance thermometer detectors (RTD) are made from platinum most often (Pt sensors) because platinum has high level of time stability, high melting point and it is chemically inert. As for the requirement defining to make maximum use of quality properties of these sensors it implies that the sensors with 3-wir or 4-wire connection must be used. It means that the controllers compensate the resistance of line that brings error into measurements. These sensors can be connected by means of standard types of cables; in practice the most frequent cables are those of three-wire type ones
 
The dependence of resistance or voltage of sensors on temperature is prescribed very strictly by standards IEC-751 (for RTD) and IEC 584.1 (for TC - thermocouples), it should be pointed out that WATLOW manufacturer meets these standards requirements with more than persuasive reserve and therefore WATLOW ranks among worldwide leading companies.
 
Thermocouple basic characteristics:
Type
Range
Standardn tolerance
Increased tolerance
Application
B
870 up to1700C
+/- 0,5%
+/- 0,25%
Suitable for extreme high temperatures
E
0 up to870C
+/- 1,7C
+/- 1,0C
Suitable for an application in vacuum a oxidizing atmosphere
J
0 up to760C
+/- 2,2C
+/- 1,1C
Suitable for oxidizing, reducing, inert atmosphere and vacuum as well
K
0 up to1260C
+/- 2,2C
+/- 1,1C
Suitable for oxidizing and inert atmosphere, not suitable for vacuum
N
0 up to1260C
+/- 2,2C
+/- 1,1C
Suitable for frequent and big temperature changes, irresponsive/ inactive to neutron flux (suitable for nuclear industry)
R
0 up to1480C
+/- 1,5C
+/- 0,6C
Suitable for high temperatures, resistant to corrosion and oxidation
S
0 up to1480C
+/- 1,5C
+/- 0,6C
-dtto-
T
0 up to370C
+/- 1,0C
+/- 0,5C
The most suitable sensor for the purpose of measurement of low temperatures, Suitable for cryogenic applications, it is possible to use it in vacuum, oxidizing and reducing atmosphere
 
Basic characteristics of resistance temperature detectors Pt100 in accordance with the standard IEC-751:
Temperature [C]
Resistance [Ohm]
Class A
Class B
-200
18.52
+/- 0.55C
+/- 1.3C
-100
60.26
+/- 0.35C
+/- 0.8C
0
100
+/- 0.15C
+/- 0.3C
100
138.51
+/- 0.35C
+/- 0.8C
200
175.86
+/- 0.55C
+/- 1.3C
300
212.05
+/- 0.75C
+/- 1.8C
400
247.09
+/- 0.95C
+/- 2.3C
500
280.98
+/- 1.15C
+/- 2.8C
600
313.71
+/- 1.35C
+/- 3.3C
650
329.64
+/- 1.45C
+/- 3.6C
 
Other types of sensor are available upon request...