Transducers are often employed at the boundaries of automation, measurement, and control systems. Before choosing a transducer we have to ensure that the transducer is suitable for our need. These are factors which may influence the selection.
Operating principle:
There are operating principles such as resistive, inductive, capacitive, piezoelectric, photo-voltaic, ionization etc., . Sensitivity:
Transducer must be sensitive enough not to give an output, but to give an detectable output.
Operating range:
A transducer should have good resolution over it’s entire range of operation. We cannot choose a temperature sensing transducer that work in range 0-100 degree Celsius for a use in boiler where temperature is up to 1000 degree Celsius, that’s what it means.
Accuracy:
High degree of accuracy is needed and small value of repeatablity.
Cross-sensitivity:
Cross-sensitivity must taken into account while measuring mechanical quantity. Cross-sensitivity must reduced. Because when transducer subjected to measure variations in one plain, while actual quantity to be measured is in another plain.
Error:
A transducer must avoid error. For which a transducer should maintain expected input output relationship by it’s transfer function.
Transient & Frequency response:
Transducer should meet desired time domain specifications such as peak over shoot, raise time, setting time & small dynamic error, it should flat frequency response curve with higher cut-off frequency at high limit in-order to have a high value.
Loading effect:
Transducer should have high input impedance and low output impedance to avoid loading effect.
Environment compatibility:
Under specified environment conditions the transducer maintain input-output relationship and doesn’t breakdown. Transducer should be able to withstand temperature, pressure shock etc., when subjected to it, if it is application require so.
Insensitivity to unwanted signals:
Noise should be avoided in measuring, so that a good transducer should insensitive to unwanted signals. But high sensitive to desired signals.
Usage and ruggedness:
Ruggedness both of mechanical and electrical intensities of transducer VS it’s size and weight must be considered while selection.
Electrical aspects:
Length and type of cable required must be considered. Signal to noise ratio must be taken care. Frequency response limitation must be taken to account.
Stability & reliability:
Should have high degree of stability during it’s operation & storage life. Reliability should be assure in case of failure of transducer in-ordered that functioning of the instrumentation system continues uninterrupted.
Static characteristics
Apart from low static error transducers should have a low non linearity, high resolution, and a high degree of repeat-ability. Transducer selected should be free from temperature effect and load alignment effects. it should not need frequent calibration.