Technical documents
FAQRTD (PT-100)
Resistance thermometers, also called resistance temperature detectors (RTDs), are sensors used to measure temperature. Many RTD elements consist of a length of fine wire wrapped around a ceramic or glass core but other constructions are also used. The RTD wire is a pure material, typically platinum, nickel, or copper. The material has an accurate resistance/temperature relationship which is used to provide an indication of temperature. As RTD elements are fragile, they are often housed in protective probes.
Common Temperature Probes style
RTD temperature and resistance correspondence table
Resistance thermometer standard
DIN EN 60751 Class A and Class B
α=0.00385 ITS-90
t≥0°C：
R(t)=R0⋅(1+A⋅t+B⋅t2)
with
A=3.9083⋅10-3°C-1
B=-5.775⋅10-7°C-2
R0=100Ω
t<0°C：
R(t)=R0⋅[1+A⋅t+B⋅t2+C⋅(t-100°C)⋅t3)]
with
A=3.9083⋅10-3°C-1
B=-5.775⋅10-7°C-2
C=-4.183⋅10-12°C-4
R0=100Ω
Class B：
dt=±(0.3+0.005⋅|t|)°C
1/3 DIN=1/3⋅ Class B dt
1/5 DIN=1/5⋅ Class B dt
1/10 DIN=1/10⋅ Class B dt
Class A：
dt=±(0.15+0.002⋅|t|)°C
RTD accuracy comparison table
DIN 43760. IEC 751 BS 1904
| °C | 1/10 DIN | 1/5 DIN | 1/3 DIN | CLASS A | CLASS B | CLASS C | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ±°C | ±Ω | ±°C | ±Ω | ±°C | ±Ω | ±°C | ±Ω | ±°C | ±Ω | ±°C | ±Ω | |
| -200 | 0.13 | 0.06 | 0.26 | 0.11 | 0.44 | 0.19 | 0.55 | 0.24 | 1.3 | 0.56 | 2.27 | 1.15 |
| -100 | 0.08 | 0.03 | 0.16 | 0.06 | 0.27 | 0.11 | 0.35 | 0.14 | 0.8 | 0.32 | 1.77 | 0.71 |
0 |
0.03 | 0.01 | 0.06 | 0.02 | 0.1 | 0.04 | 0.15 | 0.06 | 0.3 | 0.12 | 1.27 | 0.5 |
100 |
0.08 | 0.03 | 0.16 | 0.05 | 0.27 | 0.1 | 0.35 | 0.13 | 0.8 | 0.3 | 1.77 | 0.67 |
200 |
0.13 | 0.05 | 0.26 | 0.1 | 0.44 | 0.16 | 0.55 | 0.2 | 1.3 | 0.48 | 2.27 | 0.83 |
300 |
0.18 | 0.06 | 0.36 | 0.13 | 0.6 | 0.21 | 0.75 | 0.27 | 1.8 | 0.64 | 2.77 | 0.98 |
400 |
0.23 | 0.08 | 0.46 | 0.16 | 0.77 | 0.26 | 0.95 | 0.33 | 2.3 | 0.79 | 3.27 | 1.1 |
500 |
0.28 | 0.09 | 0.56 | 0.19 | 0.94 | 0.31 | 1.15 | 0.38 | 2.8 | 0.93 | 3.77 | 1.22 |
600 |
0.33 | 0.1 | 0.66 | 0.21 | 1.1 | 0.35 | 1.35 | 0.43 | 3.3 | 1.06 | 4.27 | 1.32 |
650 |
0.36 | 0.11 | 0.72 | 0.23 | 1.2 | 0.38 | 1.45 | 0.46 | 3.6 | 1.13 | 4.52 | 1.36 |
700 |
- | - | - | - | - | - | - | - | 3.8 | 1.17 | 4.77 | 1.41 |
800 |
- | - | - | - | - | - | - | - | 4.3 | 1.28 | 5.27 | 1.49 |
850 |
- | - | - | - | - | - | - | - | 4.6 | 1.34 | 5.52 | 1.56 |
