Sensor are devices which produce a
proportional output signal
(mechanical, electrical, magnetic etc.,)
when exposed to a physical
phenomenon (pressure, temperature,
displacement , force etc.,).
4. Performance terminology
• Static characteristics
– Static characteristics of an instrument are the
parameters which are more or less constant or varying
very slowly with time.
• Dynamic characteristics
– Sensors and actuators respond to inputs that change
with time. Dynamic characteristics of an instrument are
the parameters which are varying with time.
5. Static characteristics
Range – e.g.: a thermocouple may have a range of -100
Span : maximum value of input – minimum value of
Error : measured value – true input value
Sensitivity: it is defined as the change in output per
change in input
6. Static characteristics
Hysteresis: it is defined as the maximum difference
in output for a given input when this value is
approached from the opposite direction.
Linearity: it is refer to the output that is directly
proportional to input over its entire range.
7. Static characteristics
• Repeatability: it is defined as the ability of the sensor
to give same output reading when the same input value
is applied repeatedly under the same operating
• Reproducibility: it is defined as the degree of
closeness among the repeated measurements of the
output for the same value of input under the same
operating conditions at different times.
8. Static characteristics
Stability : it means the ability of the sensor to
indicate the same output over a period of time for a
Dead time: it is the time taken by the sensor from the
application of input to begin its response and change.
Resolution: it is defined as the smallest change that
can be detected by a sensor