# 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BS 1904 : Industrial platinum resistance thermometer sensors (1984) (note this standard was superseded by BS EN 60751)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 R_{t} is defined as;

If the temperature is between 0 °C to 850 °C, the resistance of a platinum thermometer R_{t} is defined as;

Where | ||
---|---|---|

R_{0} |
= | 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.