For many years, WIKA has been among the leading manufacturers of high-quality industrial temperature measuring instruments. Our experience and know-how in the construction of temperature sensors sets us apart.
The term temperature sensor, with electrical thermometers, describes a unit from one or more temperature sensors and a usage-specific protection, which can consist of, for example, connection head, neck tube, thermowell or a hand grip. The sensor element built into the temperature sensor takes the actual measurement and converts the measured temperature into an electrical signal.
With WIKA, temperature sensors in industrial temperature measurement are essentially divided between the following measuring principles:
Thermocouples
Thermocouples from WIKA are suitable for the measurement of high temperatures of up to +1,600 °C. The low diameter of a sheathed thermocouple temperature sensor enables a response time that is as fast as is possible with a resistance thermometer.
Thermocouples consist of two different metals which are bound together to form the 'thermocouple'. The connection point (hot junction) represents the actual measuring point of the temperature sensor, the wire ends are designated as the cold junction. When there is a temperature change at the measuring point of the temperature sensor, due to the different electron densities of the metals and the temperature difference, a voltage is generated between the hot and cold junctions. This is approximately proportional to the temperature of the measuring point of the temperature sensor (Seebeck effect).
Resistance thermometers
A resistance thermometer has its strengths in the low and medium temperature ranges of -200 … +600 °C. In industry, mainly Pt100 or Pt1000 measuring resistors are used. If the sensor element of the temperature sensor detects an increase in temperature, then its resistance also increases (positive temperature coefficient). The resistance of a Pt100 resistance thermometer at 0 °C is 100 Ohm, for a Pt1000 resistance thermometer it is 1,000 Ohm.
Basically there are two types of measuring resistors differentiated in temperature sensors: Thin-film measuring resistors and wire-wound measuring resistors. The advantages of thin-film measuring resistors are their small overall size and high vibration resistance with the appropriate construction of the temperature sensor. Thin-film measuring resistors have come to represent the standard sensor design, provided that they are not ruled out as a result of their temperature range (measuring ranges for accuracy class B temperature sensors: Thin film measuring resistors -50 … +500 °C, wire-wound measuring resistors -200 … +600°C).
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