In this article I will describe about electrical transducer and characteristics of transducer. What are the main types of characteristics of transducer, how they work and their applications and advantages.
Transducer is a physical device that receives energy from one system and transmits it into same form or another form of another system. There are three main parts included in its working principle. First is sensor, second signal conditioning unit and last one is data representation. A sensor is an electronic device that sense energy or some physical quantity i.e temperature, pressure, speed, water level etc. or in other words sensor is used to detect some physical quantities at specific level. If any change in the input, sensor is able to find its reason. The nature of physical quantities is non-electrical. After passing through sensor, signal conditioning unit is applied like amplifiers, analog to digital converter, modulators, filters, rectifiers. It is implemented with respect to desired output of a signal. At last data is represented to any measured scale like a LCD display or any other form.
Efficiency of a transducer is the ratio of output power to input power.
E(%) = x/y *100
y = Output power,
x = input power
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Characteristics of transducer
There are two types of characteristics of transducer to define the performance of a system. It is important to define performance parameters of a system.
- Static characteristics
- Dynamic characteristics
In this type of transducer, the set of performance is established by static tuning. It maintains static performance of parameters i.e precision (accuracy), threshold, sensitivity, repeatability, stability, drift, linearity, resolution, reproducibility, differential linearity, integral linearity, noise, maximum input, dynamic range, saturation level, hysteresis, input and output impedances. The measured parameters are varying slowly with respect to time or take a constant value.
It is defined as the ratio of measured value to standard value. It indicates the error value of a system. When the measured value goes to the nearest of ideal value or standard value its accuracy becomes higher.
The smallest difference of images or figures is discriminated of some type of units i.e pixels or inches etc. When an image is measured in pixels and compared its value to standard image size then it is called as a resolution of that image.
When a number of outputs are measured consecutively by applying the same value of input during the same operating conditions then it called as repeatability.
Hysteresis is one the main characteristics of transducer which is measured for some parameter and it gives differ value from the previous one at display by applying the same value of input. The input value gives an increasing behavior with the respect to another parameter which shows decreasing behavior of the same system. Hysteresis loop of elastic is shown in figure.
Figure: Hysteresis loop of elastic characteristics of transducer
The number of increments of the input are same with respect to the output increment then it is known as the linear increment or linear output.
The minimum value is observed by the observer or standard value is set for a system. When measured value is noticed which is above the desired level then value is to be “above the threshold value”. In figure 1.2 threshold level is represented.
Figure: threshold voltage or time over threshold shows
In this type of transducer, the set of performance is dynamic. When the performance parameter is measured and varies with respect to time then parameter said to be dynamic for a specific system. It does not maintain the static performance. It includes speed of response, fidelity, bandwidth and dynamic error.
The range of frequency which is traveled or transmitted to the desired destination within a given band is said to a bandwidth of a signal.
- Response time
The quantity is measured in that time and new equilibrium value of quantity is measured within a time is known as a response time.
- Settling time
Settling time is that time in which is not detected any variation of a signal. Variations can occur change of physical quantity. In figure 1.3 shows settling time of PID controller.
- Rise time
The rise time is that in which the measured quantity is observed linear behavior by the observer. See figure 1.2, the graph of PID controller.
Figure: Settling time and rise time of proportional integral derivative
Types of Transducer
There are two main types of transducer which is used in our applications.
- Electrical transducer
- Mechanical transducer
The physical changes of measured quantities at the electrical output of transducer for an electrical system are known as electrical transducers. It is further divided into Active Electrical Transducer and Passive Electrical Transducer.
Active Electrical transducers are those in which active components are included in a system like Magnetostrictive Transducers, Photoelectric Transducers, Piezoelectric Transducers, Electromechanical Transducers, Electrochemical Transducers, Ionization Transducers, Thermoelectric Transducers etc.
Passive Electrical Transducer are those in which passive components are included in a system like Resistive Transducers, Capacitive Transducers and inductive Transducers etc.
The physical changes of measured quantities at the mechanical output of transducer for a mechanical system are known as electrical transducers. The measured physical quantities are temperature, pressure, level of a liquid, torque, force, flow rate etc.
Types of transducers and their applications
- Photo electric transducers
Voltages are produced, when the light is come to the photo electric transducer.
- Ultrasonic transducers
These type of transducer is used to measure flow rate or floe level in ultrasonic waves.
- Piezoelectric transducers
These type of transducers are used to measure force, acceleration and pressure. Voltages are produced by applying force in it.
- Hydro-pneumatic transducers
These type of transducers is used to measure velocity, speed, flow level of water. Devices of pitot tube, turbines & vanes are used in it.
- Pressure transducers
These are used to measure the physical quantities which is used in converting pressure energy into electrical energy. They are used in sensing of pressure, altitude, flow rate, level of depth. It is also used in vehicles in which converting force into electrical energy.
- Temperature transducer
This type of transducers is used to convert temperature into different forms of energy like electrical, mechanical or pressure.