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Type K thermocouple accuracy at 500 °C
What IEC 60584-1 allows a type K thermocouple at 500 °C, class by class, and what the rest of the measurement adds.
Tolerance by class
| Class | Tolerance (°C) | % of reading |
|---|---|---|
| 1 | ±2.00 | ±0.40 % |
| 2 | ±3.75 | ±0.75 % |
| 3 | not defined at this temperature | |
At 500 °C
- EMF
- 20.644 mVcold junction at 0 °C
- Sensitivity
- 42.63 µV/KNIST ITS-90
- Cold-junction factor
- 0.950a 1 K error at 25 °C terminals reads as this many K
Example: the whole measurement
| Term | Assumption | Error |
|---|---|---|
| Sensor tolerance | Class 1 | ±2.000 K |
| Cold junction | ±0.5 K, 25 °C | ±0.475 K |
| Transmitter input | ±0.5 K | ±0.500 K |
| Analog output | ±0.03 % × 1000 K | ±0.300 K |
| Ambient effect | ±0.1 % / 10 K × 20 K | ±2.000 K |
| Total probable error | RSS | ±2.93 K |
| Worst case | Σ | ±5.28 K |
An example with typical datasheet figures, not a statement about any product. Enter your own values in the calculator.
How the tolerance is defined
IEC 60584-1 gives each class as a fixed value or a fraction of |t|, whichever is larger, within a temperature range that depends on the type. The table is that rule evaluated at 500 °C. The limits apply to new thermocouple wire as supplied; drift in service is not included.
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