For the automated recalibration of important temperature measuring chains in power plants in a temperature range from 530°C to 650°C, thermocouples with integrated miniature fixed-point cells have been developed. Practical long-term tests were successfully run with 7 different high-purity metals and binary alloys presenting phase transformation temperatures in this temperature range. A heating element additionally integrated into the thermocouple permits to carry out a recalibration of the entire measuring chain which can be set off from outside, also at constant medium temperatures. In the practical application, a calibration uncertainty at the fixedpoint temperature of about 0.2 K, and measuring uncertainties at the operating temperature of <1 K are achieved.
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