Transducers

TRANSDUCERS

Transducer is a measuring device which measures and converts non electrical variable into electrical variable is known as transducer.

Based on operating principle used output and input they accept transducers are classified into five types

1.Classification based on transduction principle

2.Active and passive transducers

3.Analog and digital transducers

4.Primary and secondary transducers

5.Transducers and inverse transducers

1. Classification based on transduction principle:

Based on the transduction principle the classification I.e. how the input variable being converted into capacitance, Resistance and inductance values. These three elements are named as

1.Capacitive transducer

2.Resistive transducer

3.Inductive transducer

2. Active and passive transducers:

Active transducers are also known as self generating type transducers. In active transducers no external excitation is required to provide output, they generate their own current or voltage output.

Examples:

1.Photovoltaic cell – used in light meters, solar cells

2.Thermocouple – used for temperature measure

3.Piezoelectric crystal – vibrations measuring

Passive transducers are also named as externally powered transducers. These transducers requires an external excitation to provide their output. The passive transducers are of three types

1.capacitive transducers – measure liquid level

- noise and thickness measure

2. Resistive transducer – temperature, pressure, displacement

3. Inductive transducers – pressure, vibrations, position.

3.Analog and digital transducers:

Analog transducer:

The transducer which produce it output in analog form or a form which is a continues function of time is referred as analog transducer.

*The below block diagram consists of primary sensor, transduction element, analog indicator.

The physical variable is applied to primary sensor. This Sensor senses the quantity of input. The transduction element converts mechanical signal into electrical signal and gives to analog indicator in the form of continuous function of time.

Digital transducer:

The transducer which gives output in he form of digital. The below block diagram consists of analog transducer and analog to digital converter, when quantity to be measured is applied, the analog transducer produces the analog signal. The converter converts analog to digital, hence the output becomes digital.

Advantages of electrical transducers:

1. For controlling electrical systems less power is utilized

2. Friction and mass inertia problems are minimized.

3. Attenuation and amplification of electrical signal is done easily.

4.Used for remote monitoring, controlling and recording.