Question

A temperature sensor having a range of 0-100°C has a worst case accuracy specification of ± 1.0% of true value of ± 0.3% of full scale, whichever is higher. The sensitivity of the sensor is experimentally obtained by taking its readings at true temperatures 25°C and 75°C. The maximum error in sensitivity, expressed as percentage of its ideal value is
1. ± 0.105%
2. ± 0.21%
3. ± 1.05%
4. ± 2.1%

Answer 1

Correct Answer - Option 3 : ± 1.05%

Sensitivity of temperature sensor \(= \frac{V}{{temp}}\)

Accuracy specification = ± 1.0% of true value (or) ± 0.3% of full scale.

Full scale reading = 100°c

While measuring 25°c

The error will be = max (1% of 25, 0.3% of 100)

= max (0.25, 0.3)

= 0.3°c

While measuring 75°c,

The error will be = max (1% of 75, 0.3% of 100)

= max (0.75, 0.3)

= 0.75°c

The maximum error in sensitivity,

\(\% \;error = \frac{{ - \left( {\frac{V}{{75}} - \frac{V}{{25}}} \right) + \left( {\frac{V}{{75.75}} - \frac{V}{{25.3}}} \right)}}{{\left( {\frac{V}{{75}} - \frac{V}{{25}}} \right)}} \times 100\)

= -1.28%