Question

Consider the following statements:

Piezoelectric transducer has

a) a very good HF response

b) typical output voltage of the order of  1 mV to 30 mV per unit of acceleration

c) no requirement of external power and is self-generating

d) no response for static conditions

Which of the above statements are correct?
1. a, b and c only
2. a, b and d only
3. c and d only
4. a, b, c, and d

Answer 1

Correct Answer - Option 4 : a, b, c, and d

Piezoelectric transducer:

• It (also known as a piezoelectric sensor) is a device that uses the piezoelectric effect to measure changes in acceleration, pressure, strain, temperature, or force by converting this energy into an electrical charge.
• It has no requirement of external power and is self-generating
• It has a very high sensitivity. So, it has a high-frequency response i.e. the parameters change very rapidly.
• The steady-state response of the piezoelectric transducer to a constant displacement (static conditions) is zero. Hence, it cannot be used for the measurement of static displacement and only used for dynamic displacement.
• It has the output voltage of the order of  1 mV to 30 mV per unit of acceleration

 

Important Points:

Active transducers:

• Active transducers (self-generating) are those which do not require any power source for their operation.
• They work on the energy conversion principle. They produce an electrical signal proportional to the input (physical quantity).
• Piezoelectric, thermocouple, and photovoltaic cell transducers are some examples of active transducers.

 

Passive transducers:

• Transducers which require an external power source for their operation is called a passive transducer.
• They produce an output signal in the form of some variation in resistance, capacitance, or any other electrical parameter, which then has to be converted to an equivalent current or voltage signal.
• LVDT is an example of a passive transducer. LVDT is used as an inductive transducer that converts motion into the electrical signal.