This is in a sense the reciprocal or converse function of the equation for converting voltage to temperature:

For all types of thermocouples (except K at t>0°C), we have:

$$ V(mV) = \mathop \sum \limits_{i = 0}^n {\left( {{t_{90}}} \right)^i} $$

For type K thermocouples at temperatures above 0°C, we have:

$$ T\left( {^\circ C} \right) = {T_{inf}}\left( {^\circ C} \right) + \frac{{V – {V_{inf}}}}{{{V_{sup}} – {V_{inf}}}} $$

Ci = Coefficients from C0 to Cn

t90 = Temperature of the thermocouple in °C

a0 to a2 = Specific coefficients of exponentiation only for type K thermocouples and temperatures above 0 °C

e= natural logarithm constant: 2.71828…

Example of coefficients for type K thermocouples | ||

Temperature (°C) | -270 to 0 | 0 to 1372 |

c_{0} | 0 | -0.176004136860e-1 |

c_{1} | 0.394501280250e-1 | 0.389212049750e-1 |

c_{2} | 0.236223735980e-4 | 0.185587700320e-4 |

c_{3} | -0.328589067840e-6 | -0.994575928740e-7 |

c_{4} | -0.499048287770e-8 | 0.318409457190e-9 |

c_{5} | -0.675090591730e-10 | -0.560728448890e-12 |

c_{6} | -0.574103274280e-12 | 0.560750590590e-15 |

c_{7} | -0.310888728940e-14 | -0.320207200030e-18 |

c_{8} | -0.104516093650e-16 | 0.971511471520e-22 |

c_{9} | -0.198892668780e-19 | -0.121047212750e-25 |

c_{10} | -0.163226974860e-22 | |

Exponential coefficients for temperatures above 0 °C | ||

a_{0} | 0.1185976 | |

a_{1} | -0.1183432e-3 | |

a_{2} | 0.1269686e+3 |

**VOLTAGE OF DIFFERENT THERMOCOUPLES FOR A TEMPERATURE OF 350 °C**

Voltage calculated in mV | |||

Type | By ITS-90 table | Voltage | Difference in % |

B | 0,596 | 0,596 | -0,018 |

E | 24,964 | 24,964 | 0,001 |

J | 19,090 | 19,090 | 0,002 |

K | 14,293 | 14,293 | 0,001 |

N | 11,136 | 11,136 | 0,002 |

R | 2,896 | 2,896 | 0,007 |

S | 2,786 | 2,786 | -0,008 |

T | 17,819 | 17,819 | -0,002 |