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Air Compressor


What is Air compressor and how Air compressor works

An air compressor is a device that converts power usually from an electric motor, a diesel engine or a gasoline engine into kinetic energy by compressing and pressurizing air, which can be released in quick bursts. 

Different types of Air compressors

  • Reciprocating compressor
  • Rotary screw compressor
  • Rotary vane Compressor
  • Centrifugal compressor
According to the number of stages the compressor can be divided as
  • Single stage compressor
  • Multi stage compressor

What is a Reciprocating compressor and how Reciprocating compressor works

Reciprocating compressors are positive displacement compressors and can be found in ranges from fractional to very high horse powers. It works by filling an air chamber with air and then reducing the chamber’s volume. Reciprocating compressors work in a very similar manner as internal combustion engine but basically in a reverse process. They have cylinders, pistons, crankshafts, valves and housing blocks. These compressors are the most commonly found compressors on portable air compression units.

Advantages of Reciprocating Compressor
  • Easy to install
  • Simple design
  • Lower cost
  • Large range of horse power
  • Can reach high pressures
  • High efficiency for two stage compressors
Disadvantages of Reciprocating Compressor
  • Higher maintenance cost
  • Potential for vibration problems
  • Many moving parts

What is a Rotary screw compressors and how Rotary screw compressor works

Rotary screw compressors use two meshing helical screws known as rotors to compress the gas. As the two helical screws are turned the volume is reduced. This results in an increase in air pressure. In an oil-flooded rotary screw compressor lubricating oil bridges the space between the rotors. This results in a hydraulic seal and transferring mechanical energy between the driving and driven rotor. Air enters at the suction side and moves through the threads as the screws rotate. The meshing rotors force the air through the compressor and the gas exits at the end of the screws. After the compression cycle, the air and the oil must be separated before air can be used by the air system.

Advantages of Rotary screw compressors
  • Simple design and easy installation
  • Low cost
  • Fewer moving parts
Disadvantages of Rotary screw compressors
  • Shorter life than other types
  • Single stage designs may have lower efficiency

What is Rotary Vane Compressors and how Rotary Vane Compressors works

Rotary Vane Compressors are positive displacement compressors. The pump consists of a rotor, stator, and blades. The number of blades could be ranging from 8 to 12. The slotted rotor is arranged within the stator providing a crescent shaped swept area between the intake and exhaust ports. As the rotor turns a single revolution, compression is achieved as the volume goes from a maximum at the input and minimum at the output.

Advantages of Rotary Vane Compressors
  • Simple design and easy to install
  • Since a rotary vane does not operate at close tolerances, it's life expectancy exceeds those compressor designs that depend on close tolerance
  • Low cost
  • Fewer moving parts
Disadvantages of Rotary Vane Compressors
  • Single stage designs may give lower efficiency
  • Not recommended for high pressures

What is Centrifugal Compressors and how Centrifugal Compressors works

Centrifugal Compressors are not positive displacement compressors like the Reciprocating, Screw or Vane Compressors. Centrifugal compressors use a rotating disk or impeller in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser section converts the velocity energy to pressure energy. These machines have inter coolers between each stage to cool the air as well as remove 100% of the condensate to avoid impeller damage due to erosion.

Advantages of Centrifugal Compressors
  • Can give high pressures
  • Lubricant free air
Disadvantages of Centrifugal Compressors
  • High cost compared to other types
  • Large frontal area for given airflow

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    Sensor Measurement System


    A typical sensor measurement system has:
    • An input stage consists of protection circuitry and amplifier. In some circuits, the amplification is incorporated into the A/D converter.
    • A/D converter.
    • A Microcontroller takes the data from A/D converter, process the data and converts it to a form readable by the user  

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    What is a load cell and how load cell works


    A load cell is a device that is used to convert a force into electrical signal. Strain gauge load cells are the most common types of load cells. There are other types of load cells such as hydraulic (or hydrostatic), Pneumatic Load Cells, Piezoelectric load cells, Capacitive load cells, Piezo resistive load cells..etc.
    Load cells are used for quick and precise measurements. Compared with other sensors, load cells are relatively more affordable and have a longer life span.

    How Strain Gauge load cell works
    The principle of operation of the Strain Gauge load cell is based on the fact that the resistance of the electrical conductor changes when its length changes due to stress. Cu Ni alloy is commonly used in strain gauge construction as the resistance change of the foil is virtually proportional to the applied strain. The change in resistance of the strain gauge can be utilized to measure strain accurately when connected to an appropriate measuring circuit. A load cell usually consists of four strain gauges in a Wheatstone bridge configuration. The electrical signal output is typically very small in the order of a few millivolts. It is amplified by an instrumentation amplifier before sending it to the measurement system. The output can be Digital or Analog (0-5V) depending on the application.

    How Capacitive Load Cell Works
    Capacitive load cells is based on the principle where the capacitance of a capacitor changes as the load presses the two plates of a capacitor closer together. The construction of a capacitive sensor is simpler than a resistive load cell. 
    Capacitive techniques can be used to measure proximity, humidity, tilt, force, torque, fluid quality, acceleration and many other physical parameters. It is a very versatile parameter that offers tremendous sensitivities in a small package. The capacitive technology is more rugged than strain gauge designs and can therefore be used in a wider variety of engineering applications.

    How Hydraulic Load Cell works
    Hydraulic load cells are force-balance devices, measuring weight as a change in pressure of the internal filling fluid. In hydraulic load cell, a load or force acting on a loading head is transferred to a piston that in turn compresses a filling fluid confined within an elastomeric diaphragm chamber. As the force increases, the pressure of the hydraulic fluid increases. This pressure can be locally indicated or transmitted for remote indication or control. This sensor has no electric components and immune to transient voltages so it is ideal for use in hazardous areas. The advantages of Hydraulic load cells are it is expensive and very complex.

    How Pneumatic load cell works
    Pneumatic load cells operate on the force-balance principle. These devices use multiple dampener chambers to provide higher accuracy than can a hydraulic device. Pneumatic load cells are often used to measure relatively small weights in industries where cleanliness and safety are of prime concern.
    Advantages of Load cell 
    • Rugged and compact construction
    • No moving parts
    • Can be used for static and dynamic loading
    • Highly Accurate
    • Wide range of measurement
    • Can be used for static and dynamic loading

    Disadvantages of Load cell

    • Mounting is difficult
    • Calibration is a tedious procedure
    How to select a load cell
    Below are some of the important parameters that need to be considered while selecting the load cell.
    • Size  
    • Accuracy
    • Weight range 
    • Operating temperature 
    • Duration of measurements 
    • Mounting
    • Output type 
    • Cost
    • Direction of loading  
    • Type of load cell
     
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    How Torque Sensor Works


    A Torque Sensor is a sensor that converts a torsional mechanical input into an electrical output signal.
    The torque sensor is used to measure the torque on a rotating system such as an engine, crankshaft, gearbox, transmission, etc. Torque can be divided into two types-Static torque and Dynamic torque.
    Static torque is relatively easy to measure compared to dynamic torque. Dynamic torque is not so easy to measure since it normally requires transfer of some effect (electric or magnetic) from the shaft being measured to a static system.
    Torque can be measured by rotating strain gauges as well as by stationary proximity sensors.
    Rotary sensors must be mounted on the shaft. An integral slip ring assembly is used to transfer the electrical signal from rotating electronics to stationary electronics. The slip ring consists of brushes which rub on rotating ring, providing an electrical path for the incoming excitation and the outgoing signal voltage. At low to moderate speeds the electrical connection between the rings and brushes are relatively noise free, but at higher speeds noise will severely degrade their performance.
    Typical max speeds will be in the 5000 rpm range for a medium capacity torque sensor. Finally, the brush ring interface is a source of drag torque that can be a problem especially for very low capacity measurements where the driving torque will have trouble overcoming the brush drag.
    Proximity and displacement sensors can also detect torque by measuring the angular displacement between shaft's two ends. By fixing two identical toothed wheels to the shaft at some distance apart the angular displacement caused by the torque can be measured. Proximity sensors or photocells located at each toothed wheel produce output voltages whose phase difference increases as the torque twists the shaft.

    Applications of Torque sensor
    • Determining the power of engine or motor
    • Clutch testing
    • Motor/Pump testing
    • Automotive brake testing

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    What is Pressure Sensor and how Pressure Sensor Works


    A pressure sensor also known as pressure transducer is used to measure pressure typically of gases or liquids. It converts pressure into an analog electrical signal such as a voltage output or current output which can easily be measured.

    There are different types of pressure sensors
     Absolute pressure sensor: measures the pressure relative to perfect vacuum.
    Gauge pressure sensor: measures the pressure relative to atmospheric pressure.
    Vacuum pressure sensor: Vacuum pressure sensors measure pressure that is less than 0 PSI.
    Differential pressure sensor: measures the difference between two pressures points.
    Sealed pressure sensor: Measures the pressure relative to some fixed pressure.

     Some of the pressure sensor technologies are
    Piezoelectric
    Uses the piezoelectric effect in certain materials such as quartz to measure the strain due to pressure. Used to measure high dynamic pressures.
    Strain gage
    Strain gages are bonded into the diaphragm of the pressure transducer and wired into a Wheatstone bridge configuration. Pressure applied to the pressure transducer produces a deflection of the diaphragm which introduces strain to the gages. The strain will produce an electrical resistance change proportional to the pressure.
    Capacitive
     Uses a diaphragm and pressure cavity to create a variable capacitor to detect strain due to applied pressure.
     Electromagnetic
     Measures the displacement of a diaphragm by means of changes in inductance, LVDT, Hall Effect, or eddy current principle.

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    How Accelerometer Works

    An accelerometer Sensor is an electromechanical device that measures acceleration forces. These forces may be static or dynamic which is caused by moving or vibrating the accelerometer. By measuring the amount of static acceleration due to gravity, you can find out the angle the device is tilted at with respect to the earth. By sensing the amount of dynamic acceleration, you can analyze the way the device is moving.
    There are different types of accelerometers:
    • Piezo electric accelerometer
    • Piezo resistive accelerometer
    • Strain gage accelerometers
    How does Piezoelectric accelerometer works
    Piezo electric accelerometer is based on principle of piezo electric effect. A Piezo electric substance is one that produces an electric charge when a mechanical stress is applied.  In a Piezo electric accelerometer a mass is attached to a Piezo electric crystal which is in turn mounted to the case of the accelerometer. When the body of the accelerometer is subjected to vibration the mass mounted on the crystal wants to stay still in space due to inertia and so compresses and stretches the piezo electric crystal. This force causes a charge to be generated and due to Newton law (F=ma) this force is in turn proportional to acceleration. The charge output is converted to voltage output by the use of integral electronics (for example: in an IEPE accelerometer) or made available as a charge output (pc /g) in a charge output Piezo electric accelerometer.
    How does Piezoresistive accelerometer works
    A piezo resistive accelerometer is based on piezo resistive effect. The piezoresistive effect describes the changing resistivity of a semiconductor due to applied mechanical stress. The piezoresistive accelerometer uses a piezo resistive substrate in place of the piezo electric crystal and the force exerted by the seismic mass changes the resistance of the etched bridge network and a whetstone bridge network detects this. Piezo-resistive accelerometers have the advantage over piezo-electric accelerometers in that they can measure accelerations down to zero Hertz.
    Advantages of Piezoresistive accelerometer
    • Piezo resistive accelerometers are preferred in high shock applications.
    • They can measure accelerations down to zero Hertz.
    Disadvantages of Piezoresistive accelerometer
    • Limited high frequency response
    How does strain gauge based accelerometer works
    A strain gauged accelerometer is based on detecting the deflection of a seismic mass by using a silicon or foil strain gauge element. A whetstone bridge network detects the deflection. The deflection is directly proportional to the acceleration applied to the sensor. Like the piezo-resistive accelerometer it has a frequency response down to zero Hz.
    Advantages of Strain gauge accelerometer
    • Strain gage accelerometers are preferred in high shock applications.
    • They can measure accelerations down to zero Hertz.
    Disadvantages of Strain gauge accelerometer
    • Limited high frequency response
    Some of the Key factors while selecting an accelerometer are
    Analog vs digital: Depending on the interface to which you will be connecting the accelerometer, you need to select analog or digital output accelerometer.
    Output: Accelerometer comes with different outputs-Charge output, IEPE output, Voltage output, current output.
    Number of axis: Depending on your requirement you need to select single, double or tri axis accelerometer. The 3 axis accelerometer will measure acceleration in all directions.
    Acceleration range:  Acceleration Range is measured in units of g. 1g is equal to the earth's gravity at sea level.
    Sensitivity: is the ratio of change in acceleration (input) to change in the output signal. Sensitivity is specified at a particular supply voltage and is typically expressed in units of mV/g.
    Applications of Accelerometers:
    • Used in cars to study shock and vibrations.
    • Camcorders use accelerometers for image stabilization.
    • Still cameras use accelerometers for anti-blur capturing.
    • Used in mobile phones for multiple functions including tilt detection, motion detection..etc. 
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      How Pitot Sensor Works

      Pitot sensor is used to measure the speed of the airplane. It is a differential pressure sensor. It measures the difference between a static port (not in the air stream) and a Pitot tube which is directly placed in the path of air flow.When the plane is stationary, the pressure in both the tubes is equal and the air speed is zero. When the plane is moving, air enters the pitot sensor. This causes the pressure difference between the static tube and the pitot tube. An internal amplifier creates an amplified voltage output and hence the sensor can be connected directly to control unit and data acquisition systems. The output voltage changes with the difference in pressure between the two ports.

      Advantages
      1) Low cost
      2) Easy installation
      3) No moving parts
      4) Light weight

      Pitot sensors were used to determine the speed on the Air France Air bus plane which crashed into Atlantic Ocean on 1st June 2009.
      French investigators have concluded that the pilots received inconsistent information about their speed shortly before crash, possibly from malfunctioning the Pitot sensors.
      There were severe thunderstorms in the area of the crash and some suspicion that the aircraft was hit by lightning or encountered severe turbulence. There were a number of other aircrafts which had taken similar routes before and after this flight but none of them reported any severe weather conditions.

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      How Optical Level Sensor Works


      The Optical level sensor consists of an infrared LED and a receiver. Light from the LED is directed into a prism which forms the tip of the sensor. When there is no liquid, light from the LED is reflected within the prism to the receiver. When the liquid level rises and the prism is in water, the light is refracted out into the liquid and the amount of light received by the receiver is dropped. This drop indicates that the liquid has reached the tip of the sensor.
      Advantages:
      1) Compact
      2) Low cost
      Disadvantages:
      1) Fixed level detection.
      Applications:
      1) Level sensing
      2) Leak detection

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      Unit Converter


      From:
      		To:


      Result:
      length conversion factors provided by unitconversion.org

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      How Solenoid Valve works

      A solenoid valve is an electro mechanical valve which works on the solenoid principle. It uses the electrical energy to do the mechanical work. The solenoid consists of a coil wrapped around the core. When current is passed through the coil a magnetic field is generated around the coil. This magnetic field causes the piston to move causing the valve to open and close. The valves can be normally open or normally closed. Depending on your application you have to select a NO or NC valve. Solenoid valves have fast switching time and are highly reliable. The solenoid valves are used in almost all the industries for variety of applications for air, gas and liquid flow control.

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      What is an Actuator

      An actuator is a mechanical device which takes the energy and converts it into motion. The motion can be linear, rotary or oscillatory motion. The source of energy to the actuator can be air, liquid or electricity. The most common actuators are motors, pumps and solenoid valves.

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      How Variable Reluctance Sensor works

      The variable reluctance sensor consists of a wire wrapped around a permanent magnet. When the ferromagnetic material such as a flywheel tooth passes the sensor the magnetic field is disrupted. Due to this an AC voltage is generated, the amplitude and frequency of which depends on the speed of the flywheel. Here the polarity of the voltage is not important. The amplitude of this AC voltage also depends on the air gap i.e. the distance between the sensor and the flywheel tooth. The voltage decreases as the air gap increases and the voltage increases as air gap decreases. Since the amplitude depends on the speed and also the air gap, correct setting of the air gap is very important when measuring lower speeds. This AC signal from the sensor can be processed further to obtain the digital output.
      The variable Reluctance sensors are called as passive sensors since they don’t need external power supply for their operation.

      Advantages of Variable reluctance sensor
      • They don’t need external power supply
      • Low cost
      • Light weight
      • They are robust and can work in harsh environments
      • Can work in high temperature and high vibration environment
      Disadvantages of Variable reluctance sensor
      • Difficult to measure low speeds
      • Additional signal processing circuitry required
      Applications of Variable reluctance sensor
      • Gear tooth speed sensor
      • Turbine speed of the jet engine

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        How Magnetoresistive Sensor works

        The magnetoresistive sensors are based on the magnetoresistive effect. The magnetoresistive effect is the change of the resistivity of a current carrying ferromagnetic material due to a magnetic field. MGR sensor can be called as magnetically controllable resistors

        The below figure shows the Magnetoresistive effect.


        When the current is passed through the ferromagnetic material the internal magnetisation vector(M) of the ferromagnetic material is parallel to the current flow. When an external magnetic field is applied in applied opposite to the direction of the current flow as shown in the figure the internal magnetisation vector changes its position(M1) by an angle depending on the strength of the magnetic field. The resistance depends on the angle formed by the internal magnetisation vector(M) of the ferromagnetic material and the direction of the current(I) flow. Resistance is largest if the current flow and the internal magnetisation vector are parallel. The resistance in ferromagnetic material is smallest if the angle is 90° between the current flow and the internal magnetisation vector.

        Normally 4 sensors are connected in a Wheatstone bridge configuration to form a complete MGR sensor with each resistor arranged to maximize sensitivity and minimize temperature influences. In the presence of a magnetic field, the values of the resistors change, causing a bridge imbalance and generating an output voltage proportional to the magnetic field strength. The Wheatstone bridge configuration provides reduction of temperature drift and doubles the signal output

        The advantages of Magnetoresistive sensor are
        • Non contact operation so there is no wear and friction. Hence unlimited number of operating cycles
        • high reliability due to their rugged construction
        • Low and stable offset
        • Due to its high sensitivity it can be used to measure weak magnetic fields
        • Low sensitivity to mechanical stress
        • Much more Insensitive to vibrations than inductive sensors
        • high operating temperature
        • Wide operating frequency range (0 Hz to 1 MHz)
        • Can be used in harsh environments
        • Reasonable cost
        • Can measure zero speed
        • Small size
        • Fast response
        The Disadvantages of Magnetoresistive sensor are
        • Sensitive to interfering magnetic fields. Very strong magnetic field can damage the sensor
        • Temperature drift
        • Limited linear range
        • Poor temperature characteristics
        Some of the applications of Magnetoresistive sensor are
        • Wheel speed sensors
        • Angle measurement
        • Linear displacement measurement
        • Current measurement
        • Earth magnetic field detection for compass and navigation applications
        • Metal detection
        • Magnetic field measurement

          How Hall Effect Sensor works

          A Hall Effect sensor is a device that detects the presence of magnetic field. It is based on the Hall Effect. The Hall Effect was discovered by Edwin hall in 1869. When current is passed through the conductor and the same conductor is placed in magnetic field perpendicular to the current flow then a voltage called the hall voltage is generated perpendicular to both the current and magnetic field. This is known as Hall Effect.


          The above figure shows the Hall Effect.
          When no magnetic field is applied to the current carrying thin semiconductor material(hall element) the hall voltage(Vh) is zero. When an external magnetic field is applied to the current carrying hall element perpendicular to the current flow a Lorentz force acts on the current due to which a voltage called hall voltage(Vh) is generated perpendicular to both the current and the magnetic field. This voltage is very small (in uV) and needs amplification.

          The advantages of Hall effect sensors are
          • Non contact operation so there is no wear and friction. Hence unlimited number of operating cycles
          • High speed operation - over 100 kHz possible. Where as at high frequencies the inductive or capacitive sensor output begins to distort
          • When packed immune to dust, air, water where as capacitive sensor may get triggered by dust.
          • Can measure zero speed
          • Wide temperature range
          • Highly repeatable operation
          • Capable of measuring large current
          The disadvantages of Hall effect sensors are
          • May be affected by external interfering magnetic field
          • Large temperature drift
          • Large offset voltage
          Some of the applications of Hall effect sensors are
          • Current sensing
          • Power sensing
          • Proximity detection
          • Speed detection 

            How Magnetostrictive Sensor works

            Magnetostriction is a property of ferromagnetic materials such as iron, nickel, cobalt and their alloys to expand or contract when placed in magnetic field.
            Initially when these ferromagnetic materials are not magnetised the magnetic domains of the ferromagnetic material are randomly distributed. But when they are placed in magnetic field the magnetic domains undergo changes and are arranged in parallel.
            A magnetostrictive sensor is used to measure linear position. It basically senses the position of the permanent magnet(position magnet) to determine the distance between the permanent magnet and the sensor head.
            The main components of the magnetostrictive sensor are
            • Waveguide
            • Position magnet
            • Electronics
            • Strain pulse detection system
            • Damping module

            MTS Magnetostrictive Sensor Principle

            The basic part of the magnetostrictive sensor is the sensing element called the waveguide. The waveguide is made of ferromagnetic materials such as iron, nickel, cobalt and their alloys. The position magnet which is round in shape moves around this waveguide.

            Initially when position has to be determined the sensor electronics sends a current pulse called the interrogation pulse through the waveguide and starts the timer. So a magnetic field is created around the waveguide. When the magnetic field of the position magnet interacts with the magnetic file around the waveguide a strain pulse is generated which travels at the speed of sound on both sides. On one side this strain pulse is detected by the strain pulse detection system and then processed by the electronics and converted into electrical pulse. The position is determined based on the time the strain pulse takes to reach the strain pulse detection system. The un useful pulse which travels opposite to the electronics is damped by damping module to prevent any interference by reflections from the waveguide tip.

            Advantages of Magnetostrictive sensor: since it is non contact( the position magnet does not touch waveguide) there is no wear and friction. So there is no limitation on the number of operating cycles and is not affected by vibrations.
            Linear measurement

            Disadvantages of Magnetostrictive sensor: Dead band on both side of the sensor.( Some manufacturers can reduce the dead bands based on your requirement but cannot make it to zero)

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            Temperature range for different environments

            The operating temperature is very important parameter to be considered while selecting the sensor. The manufacturer of the sensor specifies the operating temperature in the specs sheet of the sensor.
            Below is the standard operating temperature range in commercial, Industrial, Military and Automotive environment.

            Commercial: The standard temperature range for commercial applications is 0° to +70° (32°F to 158°F)

            Industrial: The operating Temperature range for industrial applications is -40°C to +85°C (-40°F to 185°F)

            Automotive: The standard operating Temperature range for industrial applications is -40°C to +85°C (-40°F to 185°F)
            The extended temperature range for automotive environment is 40°C to +125°C (-40°F to 257°F)

            Military: The operating temperature range for military applications is -55°C to +125°C (-67°F to 257°F)

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            How LVDT works

            The Linear Variable Differential Transformer(LVDT) is a device used to measure linear displacement. The LVDT has 3 coils-one primary and two secondary, and an armature. The armature is basically a ferromagnetic core such as iron. An AC voltage is applied to the primary coil.


            The two secondary coils are connected in opposite such that the output voltage is the difference of the individual voltages of the secondary coils. When the core is at the centre both the secondary coils produces equal and opposite voltage. Hence the output voltage(Vout) is zero.
            When the core moves in left or right direction the output voltage of one secondary coil decreases and the output voltage from the other secondary coil increases. The output voltage is proportional to the distance travelled by the armature. This output voltage is used to determine the displacement.

            The advantages of a LVDT are
            • Non contact-There is no contact between the armature and the primary or secondary coils. Hence there is no friction and wear.
            • Accurate
            • Can be totally sealed and can be made to work in harsh conditions
            • Less sensitive to vibrations
            The disadvantages of a LVDT are
            • Internally non contact but externally has to be connected where the measurement has to be made
            • Not feasible for very long range measurements
            Some of the applications of LVDT are
            • Linear displacement measurement
            • Position sensing 

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              How Laser Triangulation Sensor works

              The laser triangulation sensor consists of a laser, detector and a lens before the detector to focus the beam on the detector. The detector is normally a CCD array. To do the measurement of height the laser emits a light on the surface. This laser beam is reflected from the surface and falls on the detector through the lens. Depending on the position of the beam on the detectors CCD array, the angle(α) is calculated and hence the height from the sensor to the target surface is detected. As the height increases the angle decreases and as the height decreases the angle increases.

              Advantages of Laser Triangulation Sensor
              • Since it is non contact there is no friction and wear
              • Unlimited number of operating cycles since it is not contact
              • Can measure distance to small targets since spot size of laser beam is very small
              • High accuracy
              • High Resolution
              • High speed
              • Good reliability
              • Good linearity
              • Long measurement ranges
              Disadvantages of Laser Triangulation Sensor
              • No measurement zone of few mm infront of the sensor. As the measurement range increases this also increases.
              • Could be affected if the target surface is irregular
              • Laser beam can be hazardous.
              Applications of Laser Triangulation Sensor
              • Ride height measurement on the car
              • Displacement measurement
              • Thickness measurement
              • Tyre deflection 

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                Ingress protection(IP)

                Ingress protection rating is developed by European Committee for specifying the level of protection for an electrical device.

                The IP rating normally has two numbers.
                First Digit: specifies protection from solid objects.
                Second Digit: specifies Protection from liquids.

                First Digit: Protection against solid objects
                0 No protection
                1 Protected from object of size 50 mm or more. For example hand touch
                2 Protected from object of size 12 mm or more. For e.g. a finger or similar kind objects
                3 Protected from object of size 2.5 mm or more. For e.g. tools, wires
                4 Protected from object of size 1 mm or more. For example wires or similar kind objects
                5 Protected from dust (but not entirely protected)
                6 Total protection from dust

                Second Digit: Protection against ingress of Water
                0 No protection
                1 Protected against vertically falling drops of water
                2 Protected from vertically dripping water when the enclosure is tilted to up to 15°
                from its regular position.
                3 Protected from spraying water up to 60° from vertical.
                4 Protected from spraying water from all directions.
                5 Protected against jets of water from all directions
                6 Protected against powerful jets of water
                7 Protected against the effects of immersion up to 1m (temporary immersion)
                8 Protected against continuous immersion of water beyond 1m.

                For example the most common are IP67 and IP68

                Sometimes a third number is also specified.
                Third Digit: Protection against mechanical impact
                0 Not protected
                1 Protected against 0.225 joules impact
                2 Protected against 0.375 joules impact
                3 Protected against 0.5 joules impact
                5 Protected against 2.0 joules impact
                7 Protected against 6.0 joules impact
                9 Protected against 20.0 joules impact

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                How Photoelectric proximity sensor works

                The Photo electric sensor can be used to detect both metallic and non metallic targets. The main components of a photo electric sensor are the emitter and detector.
                The emitter sends a beam of light which is then detected by detector.
                Photoelectric sensors works in different modes
                Thru-Beam: In this case the emitter and detector are 2 separate units. The emitter emits the light which is detected by the detector. A target is detected when it passes in-between the emitter and detector.
                The advantages of this mode is that the sensing range is more
                The disadvantage is 2 parts need to be mounted separately and for long range the installation could be difficult because the emitter has to be put with the detection range of the detector.

                Diffuse Reflective: In this case the emitter and detector are put in the single package in such a way that their field of view cross. Here the emitter continuously emits the light. When the target comes within the operating range of the sensor the light from the emitter is reflected off the target and detected by the detector. The advantages of this are low cost, easy installation
                The disadvantages are short sensing distance. The sensing distance depends on target size, surface and shape.

                Retro-Reflective: the main components of this sensor are the emitter, detector and the Retro-reflector. The emitter and the detector are in the same package. The Retro-reflector is placed little far from the sensor. The light from the emitter is reflected off the Retro-reflector and detected by the detector. When the target passes between the sensor and the Retro-reflector the beam is not reflected back to the detector. Here the problem can be that the beam could reflect from the target itself. For this the polarising filter is used in the sensor. Hence only the light reflected by the retro-reflector is detected by detector

                The advantages of this are low cost and easy to install
                The disadvantages are separate retro-reflector to be used, Cannot be used to detect small objects as the target has to block the entire beam from emitter, performance could be affected in case of dirt on retro-reflector, problems in detecting clear targets

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                SENSORS


                This Blog is made so that the students and engineers get the basic knowledge on the various types of sensor technologies available. This blog contains information on the working of various kinds of sensors, their advantages, disadvantages, common applications and links of best manufacturers.
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