Thermocouples measurement

In the measuring range of a specified thermocouple type, a measured voltage is converted internally into a temperature according to the set transformation. Since the channel measures a voltage internally, the corresponding measuring error in the voltage measuring range must be used.

Notice

Thermocouples measurement 1:

Basics of thermocouple technology

  • Observe the descriptions and notes on the basics of thermocouple technology in the I/O Analog Manual.
Thermocouples measurement 2:

Specifications for reference configuration with EtherCAT Terminals (internal cold junction)

The following tables with the specification of the thermocouple measurement only apply to the reference configuration with EL331x EtherCAT Terminals when using the internal cold junction.

As the cold junction of EtherCAT plug-in modules is implemented externally on the application-specific signal distribution board, the specified values are to be regarded as reference values that are only achieved with a comparable implementation.

  • The uncertainties must then be determined for the external cold junction on the application side. This temperature can then be transferred to the module for cold junction compensation and calculation of the absolute temperature via the process data.
  • The effect on the measurement of the thermocouples must then be calculated on the system side.

The specifications for the internal cold junction and the measuring range given here apply only if the following times are adhered to for thermal stabilization at constant ambient temperature:

Specification of the internal cold junction measurement

In the EL3314 and EL3314-0090, each channel has its own cold junction sensor.

Measurement mode

Cold junction

Basic accuracy: Measurement deviation at 23°C, with averaging

< ±2.0°C

Temperature coefficient

Tk

< 40 mK/K

Further Information