Error analysis of a temperature measurement system : with worked examples 1. ed

Contents 1 General/explanation of terms ................................................... 5 1.1 The temperature measurement system ................................................... 5 1.1.1 Calibration ............................................................................................................. 6 1.1.2 Adjustment ............................................................................................................ 6 1.1.3 Testing ................................................................................................................... 6 1.1.4 The standard .......................................................................................................... 6 1.1.5 Reference standard ............................................................................................... 6 1.1.6 Factory/workshop standard .................................................................................. 6 1.1.7 Traceability ............................................................................................................. 7 1.1.8 German Calibration Service (DKD) ........................................................................ 7 1.1.9 Measurement uncertainty ...................................................................................... 7 1.1.10 Systematic measurement deviations ..................................................................... 8 1.1.11 Statistical measurement deviation ......................................................................... 8 2 Measurement uncertainty components .................................. 9 2.1 Heat conduction error of the temperature probe (σMF) ....................... 10 2.2 Deviation of the temperature sensors from the standard characteristic (σMD) ................................................. 11 2.3 Stabilization (σMA) ................................................................................... 12 2.4 Self-heating of resistance thermometers (σME) ................................... 13 2.5 Thermoelectric emfs with resistance thermometer measurements (σMTh) ........................................................................................................ 13 2.6 Insulation resistance of the resistance thermometer (σMRI) ............... 14 2.7 Sensitivity of the sensor (CS) .................................................................. 15 2.8 Deviation of the reference junction temperature (σt0S) ........................ 15 2.9 Compensating cables (σVLX) ................................................................... 15 2.10 Lead resistance of resistance thermometers (σRAL) ............................ 16 2.11 Supply to the evaluation electronics (σV) .............................................. 17 2.12 Ambient temperature of the evaluation electronics (σtM) .................... 17 2.13 Processing and linearization error (σtW) ................................................ 17 2.14 Input resistance of the evaluation electronics (σB) .............................. 17 2.15 Other sources of error ............................................................................. 17 2.15.1 Installation site of the evaluation electronics ....................................................... 17 2.15.2 Galvanic currents with thermocouples ................................................................ 18 2.15.3 Leakage currents with thermocouples ................................................................ 18 2.15.4 Mechanical stress of thermocouples ................................................................... 18 2.15.5 Chemical stress of thermocouples ...................................................................... 18 2.15.6 Mechanical stress of resistance thermometers ................................................... 18 2.15.7 Long-term behavior of resistance thermometers ................................................ 18 Contents 3 Worked examples .................................................................... 20 3.1 Distribution functions .............................................................................. 20 3.2 Transmitter with thermocouple .............................................................. 22 3.3 Transmitter with resistance thermometer ............................................. 23 3.4 Precision indicating instrument .............................................................. 25 4 German Calibration Service (DKD) ........................................ 28 5 Recommended literature ........................................................ 29