C193 – BS EN 60751 and BS 1904 PRT Calculations
Description
This calculates the resistance value for a Industrial Platinum Resistance Thermometer at a given temperature (or vice versa).
References
IEC/BS EN 60751 : Industrial platinum resistance thermometers and platinum temperature sensors (2008)
BS 1904 : Industrial platinum resistance thermometer sensors (1984) (note this standard was superseded by BS EN 60751)
IEC 751(1983)
Kelton calculation reference C193
FLOCALC calculation reference F042
KIMS calculation reference K203
This calculation supercedes C105/K131
Options
Standard
- BS EN 60751
Calculation is performed in accordance with standard.
- BS 1904
Calculation is performed in accordance with standard.
Solve for
- Resistance
Select this option to calculate the equivalent resistance for a given temperature value.
- Temperature
Select this option to calculate the equivalent temperature for a given resistance value.
Output Type
- Digital
The temperature will be calculated and displayed in the selected temperature unit.
- Analogue
The temperature will be scaled to another unit, current or voltage.
Constants
Constants as defined in the standard are;
| BS EN 60751 | BS 1904 | ||
| A | = | 3.9083 x 10-03 °C-1 | 3.90802 x 10-03 °C-1 |
| B | = | -5.775 x 10-07 °C-2 | -5.802 x 10-07 °C-2 |
| C | = | -4.183 x 10-12 °C-4 | -4.27350 x 10-12 °C-4 |
Calculation
All calculations are performed in SI units unless otherwise stated.
Calculation of resistance
If the temperature is between -200 °C and 0 °C, the resistance of a platinum thermometer Rt is defined as;
If the temperature is between 0 °C to 850 °C, the resistance of a platinum thermometer Rt is defined as;
| Where | ||
|---|---|---|
| R0 | = | The resistance at 0 °C |
| t | = | The temperature |
Typical values for a pt100 are:
| Temperature (°C) | Resistance (Ω) |
| 0 | 100.0000 |
| 25 | 109.7347 |
| 50 | 119.3971 |
| 75 | 128.9874 |
| 100 | 138.5055 |
Calculation of temperature
An iterative process is used to calculate the temperature from resistance.