The standard temperature coefficient DIN 43760 of platinum wire is: α = 0.00385. For a resistance of 100 ohms at 0°C, this corrsponds to + 0,385 ohm per °C which is the average curve from 0°C to 100°C. There exists a large variety of RTD’s that have different coeffcients and ohm values at 0°C. However, the most common RTD is that with the above example, PT100, with a coeffficent of 0.00385 and an ohm value of 0°C at 100 ohms. This is what the following pages’ calculations and explanations will be based on.
|International Standards DIN 43760 (IEC 751, BS-1904, JIS C1604)|
|Parameter||Class A||Class B|
|R0||100Ω ±0,06%||100Ω ±0,12%|
|Alpha, α||0,00385 ±0,000063||0,00385 ±0,000063|
|Range||-200°C à 650°C||-200°c à 850°C|