APP NOTE
Calibrate a PID controller with a Pt100 simulator.
Feed the controller known resistances. Check what it displays. ohmSTAR sets the Pt100 resistance for any temperature you type.
Video
Watch: Platinum RTD, PID temperature controller calibration (YouTube)
Steps
- Power down. Connect ohmSTAR to the RTD terminals. For 3-wire inputs, run two leads from LO.
- Select the Pt100 table and press TABLE.
- Enter 0 °C. Note the controller reading.
- Repeat at each test point below.
- If the controller has offset and span, adjust at 0 and 200 °C. Re-check 100 °C.
Test points
| °C | Ω |
|---|---|
| 0 | 100.00 |
| 50 | 119.40 |
| 100 | 138.51 |
| 150 | 157.33 |
| 200 | 175.86 |
Values are calculated from the standard curve. They aren't an accuracy spec.
Lead resistance
On a 2-wire input, 0.39 Ω of lead reads as about 1 °C. Keep leads short or use 3-wire.
Which model
Either one. ohmSTAR steps in 0.1 Ω, about 0.26 °C per step on a Pt100. ohmSTAR+ steps in 0.01 Ω, about 0.026 °C.