Essay Example on Instrumentation And Controls Sensing Elements Research Report









Instrumentation And Controls Sensing Elements Research Report Hall Effect Name Sensing elements are any device that receives a signal or stimulus as heat or pressure or light or motion etc and responds to it in a distinctive manner according to the free dictionary They are used to detect and convert some physical parameter into useful information which can be stored and or displayed for a user to interpret A transducer is a type of sensor which changes one type of energy into another Hall effect sensors are one type of sensor element The Hall Effect was discovered by Edwin Hall who observed that when a magnetic field passes through a current carrying conductive plate perpendicular to the plane of the plate a voltage potential develops The principle which governs this is the Lorentz force illustrated in figure 1 The applied magnetic field B causes electrons to move in direction V and experiences a force F called the Lorentz force which is normal to both the field applied and the flow of current Figure1 As explained before a force is applied In response to the force electrons move to one side of the plate in a curved path around the field This causes a charge to develop and a voltage potential can be measured This voltage which develops across the plate is called the Hall voltage VH 

The formula VH IB ρ nqt where VH is the Hall voltage across the conductive plate I is the current passing through the plate B is the applied magnetic field q is the magnitude of the charge of the charge carriers ρ n is the number of charge carriers per unit volume and t is the thickness of the plate The formula shows that the Hall voltage is proportional to the strength of the field applied This field also determines the polarity of the Hall voltage That is to say if the north pole or south pole of the field is applied to the plate the Hall voltage would be a different polarity The Hall effect sensing technology is ideal In response to a magnetic field a voltage is developed The voltage is proportional to the field strength and also the polarity is affected by the orientation of the field The voltage which is developed is very low in the micro volts µV This is unusable and needs to be amplified and conditioned to form a useful sensor Although the Hall effect sensor is a magnetic field sensor it can be used as the principle component in many other types of sensing devices current temperature pressure position etc Hall effect sensors can be applied in many types of sensing devices If the quantity parameter to be sensed incorporates or can incorporate a magnetic field a Hall sensor will perform the task 

The Hall sensor senses the field produced by the magnetic field The magnetic field responds to the physical quantity to be sensed temperature pressure position etc through the input interface The output interface converts the electrical signal from the Hall sensor to a signal that meets the requirements of the application as seen in figure 1 1 figure 1 1 The sensing technology is very beneficial to certain applications and allow it to operate where other types may not The following are the benefits of the sensor type True solid state Long life 30 billion operations in a continuing keyboard module test program High speed operation over 100 kHz possible Operates with stationary input zero speed No moving parts Logic compatible input and output Broad temperature range 40 to 150 C Highly repeatable operation An example of the application of Hall effect sensors is in smartphones There are cases for the phones which contain magnets that provide the field required When the case is closed the field causes a voltage to develop which is conditioned by the software in the phone this switch causes the screen to be turned off saving the phones battery life Another example of this sensor in use is in DC motors The Hall effect sensor is used to determine the exact location or position of the motor This is useful in Hard drives for computers The sensor allows the computer to know exactly where the hard drive disk is and move to another position with great accuracy as seen in figure 1 2 A third example is in the position of a gear for machinery

There are many types of machines where the knowledge of the relative position of a gear is useful One example is in automobiles The relative position of the crankshaft and camshaft allow the car's computer to fire the ignition spark and inject fuel for the most power possible due to the knowledge of the engines position via the hall effect sensor as seen in figure 1 3 Figure 1 2 Figure1 3 References Allegro Hall Effect Sensor ICs Retrieved January 19 2018 from http www allegromicro com en Design Center Technical Documents Hall Effect Sensor IC Publications Allegro Hall Effect Sensor ICs aspx How Does a Magnetic Sensor Work Retrieved January 19 2018 from https sciencing com magnetic sensor work 5021878 html How Hall effect sensors and probes work 2017 March 30 Retrieved January 19 2018 from http www explainthatstuff com hall effect sensors html McGrayne S B Suckling E E 2018 January 18 Electricity Retrieved January 19 2018 from https www britannica com science electricity Kirchhoffs laws of electric circuits ref307243 Sensing element Retrieved January 19 2018 from https www thefreedictionary com sensing element E 2017 March 21 Sensors Different Types of Sensors Retrieved January 19 2018 from https www engineersgarage com articles sensors

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