State the working principle and specification of LVDT 

3 Answers

Answer :

Working principle: It works on the principle of mutual induction.to convert linear displacement into equivalent voltage. LVDT has a single primary winding P and two secondary windings S1 and S2 wound on a cylindrical former. S1 and S2 have equal number of turns and are connected in series opposition. A movable soft iron core is placed inside the cylindrical former. When a.c. supply is given to the primary winding, voltages are induced in both the secondary windings. When a displacement is applied to the movable core the flux linking with both the secondary winding changes and produces output voltage which is proportional to the displacement applied. The output voltage is Vo = (VS1 -VS2) where VS1 is voltage induced in S1 and VS2 is voltage induced in S2. 


Specifications of LVDT 

High sensitivity Very good linearity Ruggedness Less friction Low hysteresis Low power consumption

Answer :

Working principle:- 

image

When primary winding is excited by suitable a.c. source.It tries to produces magnetic flux. This mutual flux link with two secondary winding and as flux linkages change emf is induced in both secondaries. When core is centrally located, equal voltage is induced in both secondaries. But when core is displaced flux linkages changes and hence more voltage is induced in on secondary than the other one. The variation of o/p voltage with core position is shown fig. (a) when core is centrally located, net o/p voltage Vo is zero (theoretically). This core position is called as null position.

As core moves on either side from null positon, output voltage increases primarily dependent upon length of secondary coils. Beyond proportionality limit o/p increases at a decreasing rate until it reaches a maximum from which it drops again to the balnced condition when the core is removed. There is a phase shift as core moves both to and from from central position, so that phase measurement can be related to the direction of core motion voltage variation with core is shown fig (b).

image

Answer :

Diagram:

image

A Linear Variable Differential Transformer (RLVDT) is an electromechanical transducer that provides a variable alternating current (AC) output voltage that is linearly proportional to the linear displacement of its input shaft. LVDT is a passive inductive transducer to translate the linear motion into electrical signals. It consists of a single primary winding and two secondary windings. Secondary windings have equal number of turns and are identically placed on either side the primary winding. The primary winding is connected to an A.C. source. A movable iron core is placed inside the winding. The displacement to be measured is applied to the arm attached to the soft iron core. Since the primary coil is excited by an A.C. source, it produces an alternating magnetic field, which in turn induces alternating current or voltage in the two secondary windings. Two secondary windings are connected in series opposition to get differential output voltage. When displacement is applied to the core, inductance of one secondary winding increase and other decreases, giving differential output. The Differential output voltage= V1-V


Applications of LVDT: Measurement of displacement Measurement of weight or pressure exerted by liquid in a tank. Measurement and control of thickness of a meat sheet being rolled. Acting as a secondary transducer it can be used as device to measure force, weight and pressure

Related questions

Description : Explain the construction and working of LVDT accelerometer with the help of diagram.

Last Answer : Explanation:* The LVDT accelerometer consists of one primary and two secondary windings which are placed on either side of central code. The two ends of the core are connected with ... in the output terminal. This output voltage is directly proportional to the vibration or acceleration. 

Description : Draw Bourdon tube with LVDT setup for pressure measurement.

Last Answer : Bourdon tube with LVDT setup for pressure measurement.

Description : Explain the working and principle of LVDT.

Last Answer : LVDT: Principle: The differential voltage of two secondary windings of a transformer is varied by positioning the iron core through an externally applied force. Working  When the pressure ... upon the position of the core which in turn depends upon the pressure fed inside the bellows.

Description : Sketch and describe the working principle of LVDT.

Last Answer : Diagram Explaintion: LVDT is the example of inductive transducer, in LVDT any physical displacement of the core cause the voltage of any secondary winding to increase while simultaneously reducing the ... winding and core varies the coupling between it and two secondary windings. .:E0=E1-E2

Description : Principle of operation of LVDT is based on the variation of  A) Mutual inductance B) Self-inductance C) Capacitance D) Resistance

Last Answer : 3

Description : Explain why LVDT gives a residual output at null position. State its 2 applications.

Last Answer : LVDT : Residual voltage may be on account of I/P supply voltage and also due to harmonics produced in the o/p voltage on account of use of iron core.  OR  An incomplete magnetic ... pressure is converted into a voltage. In these applications the high sensitivity of LVDTs is a major attraction.

Description : Draw construction diagram of LVDT with label. Also state the application of LVDT. 

Last Answer : Application of LVDT 1) L.V.D.T as a primary transducer can be used for displacement measurement ranging from fraction of a mm to a few cm 2) Acting an secondary transducer, used to measure force, weight and pressure. 

Description : Draw and explain the displacement measurement system using LVDT.

Last Answer : (Or)  LVDT has a single primary winding P and two secondary windings S1 and S2 wound on a cylindrical former. S1 and S2 have equal number of turns and are ... while simultaneously reducing the voltage in the other winding. Output voltage Vo measured is equivalent to the displacement.

Description : List any four drawbacks of LVDT.

Last Answer : Drawbacks of LVDT. 1. Large primary voltage produces distortion in output. 2. Temperature affects the performance. 3. Sensitive to stray magnetic field. 4. Large displacements are required for differential output 5. It has residual voltage

Description : Consider the following transducers : 1. LVDT 2. Piezoelectric 3. Thermocouple 4. Photovoltaic cell  Which of the above are active transducers ?

Last Answer : Consider the following transducers : 1. LVDT 2. Piezoelectric 3. Thermocouple 4. Photovoltaic cell Which of the above are active transducers ? 2, 3 and 4

Description : LVDT is a:  (1) Displacement transducer (3) Acceleration transducer (2) Velocity transducer (4) Pressure transducer

Last Answer : LVDT is a: Displacement transducer.

Description : What is residual voltage of lvdt?

Last Answer : Need answer

Description : LVDT used for displacement measurement is a/an __________ transducer. (A) Passive (B) Active (C) Capacitive (D) None of these

Last Answer : (A) Passive

Description : Drawand explain LVDT accelerometer.

Last Answer : Diagram: Explanation: The LVDT accelerometer consists of one primary and two secondary windings which are placed on either side of central code. The two ends of the core ... arises in the output terminal. This output voltage is directly proportional to the vibration or acceleration.

Description : Give one application each of following transducer: (i) LVDT (ii) RVDT (iii) Capacitive (iv) Piezoelectric

Last Answer : i) LVDT ➢ LVDT used to measure force ➢ LVDT used to measure strain ➢ LVDT used to measure weight ➢ LVDT used to measure tension ➢ LVDT used to measure pressure ➢ The ... flow meters, non-destructive test (NDT) equipment's ➢ Piezoelectric materials are used in ultrasonic transducers.

Description : Sketch and describe pressure measurement system for 800 mm pressure, that contain Bourdon tube and LVDT.

Last Answer : Diagram: Explanation: The pressure measurement using bourdon tube and LVDT is shown in above figure. In this the, the bourdon tube act as primary transducer and LVDT which follows ... This set up is used for measurement of pressure which is converted into electrical signal by LVDT.

Description : Draw and describe the constructional diagram of LVDT.

Last Answer : Construction of LVDT: A differential transducer consists of a primary winding and two secondary winding. The windings are arranged concentrically and next to each other. They are wound  over a ... winding and core varies the coupling between it and two secondary windings. E0=E1-E2

Description : Which is not the disadvantage of LVDT?  a) Relatively large displacement are required for appreciable differential output b) temperature affects the performances of transducer c) low hysteresis and ... limited mechanically by the mass of the core and electrically by the frequency of applied voltage

Last Answer : low hysteresis and electrical isolation

Description : List specification of 3G W- CDMA (UMTS).

Last Answer : Specifications of UMTS are:  1. It is more robust for multipath delays.  2. It provides higher immunity towards frequency selective fading.  3. It has very high packet data rates of 2.048Mbps. ... such as voice, data, multimedia, internet etc.  11. It has global seamless connectivity (roaming). 

Description : Give the specification of three phase transformer as per IS 1180(Part-1) 1989. 

Last Answer : Specification of 3-phase transformer: 1) kVA rating of transformer 2) Voltage ratings for the primary and secondary voltages 3) HV and LV currents 4) Operating frequency of the transformer 5) % impedance of ... the manufacturer 16) Weight of core 17) Weight of winding 18) Volume of oil in litres.

Description : List specification of zener diode

Last Answer : 1. Zener Voltage 2. Maximum Zener current 3. Power dissipation 4. Operating temperature 5. Dynamic Resistance 

Description : State working principle of electric welding. 

Last Answer : Working principle of Electric welding: In resistance welding, sufficiently heavy current at low voltage is passed directly through two metals in contact to be welded. Heat is produced due to I2R ... industry. 15. For fabrication and repair work. 16. In other metal processing industries.

Description : State working principle and applications of servo motor.

Last Answer : Working Principle of Servo Motor: Basically servo motor is made up of DC motor, which is controlled by a potentiometer and some gears. Its angle of rotation is controlled by the duration of ... Packaging 6) Woodworking 7) Textiles 8) Printing 9) Robotics 10) Portable drilling 11)Process control 

Description : State working principle of universal motor with the help of diagram.

Last Answer : Working Principle of Universal motor : It is modified DC series motor which can work on AC as well as DC supply. According to basic motor principle, whenever a current carrying conductor is placed in magnetic ... They have nearly same operating characteristic for both AC and DC supply. 

Description : State the working principle of gears and give its applications.

Last Answer : Working Principle:  Gears are mechanical elements which transmit motion by means of successively engaging teeth.  Gears are used to transmit motion from one shaft to another or between ... Agricultural equipment.  Industrial construction.  Mining equipment.  Automotive equipment.

Description : State working principle of analog to digital and digital to analog conversion.

Last Answer : i) Analog-to-digital Converters: In a digital computer control system, the plant output (or controlled variable) is usually an analog signal, which is measured by sensors (or instruments). This ... that provides an output voltage or current normalized to a full-scale (FS) reference value.

Description : State working principle of column type load cell and state its any four applications.

Last Answer : Load cell is an elastic member as the primary transducer and strain gauge is the secondary transducer. When this combination is used, it is called load cell. In this case an axial compressive load causes a negative ... . 3. It is used for weighing 4. It is used to measure torque force.

Description : State working principle of A/D converter. ?

Last Answer : An A/D converter converts the analog signal which is measured by sensors to its equivalent digital form. The conversion of analog measurements to digital measurements involves three operations, namely sampling, quantization and encoding.

Description : State the working principle of thermistors 

Last Answer : A thermistor is a type of resistor whose resistance is dependent on temperature. Working principle: Whenever there is a change in temperature, the resistance of some semiconductors change . In case of ... . In case of NTC type, the resistance of the thermistor decreases with increase in temperature.

Description : State working principle of thermocouple.

Last Answer : Working principle of thermocouple. When heat is applied to junction (hot junction) of the two dissimilar metals, an emf is generated which can be measured at the other junction (cold junction). The two ... as a result of the generated emf. This current will continue to flow as long as T1>T2.

Description : With the help of neat sketch, state working principle of rotameter. 

Last Answer : Explanation- When there is no flow through the Rota meter, the float rest at the bottom of metering tube. When fluid enters the tube, the float moves up and the flow area increases. The float ... on the tube. With the help of float position and calibrated scale, we can measure the flow rate.

Description : State working principle of earth tester.

Last Answer : Earth tester:-The resistance of the earth is measured with the help of earth tester. It consists of a hand cranked type generator, the magnet poles, crossed coils and flexible spirals. It consists ... deflection of the pointer will indicate directly resistance in ohm of the earth under test.

Description : State working principle of PMMC instrument.

Last Answer : Working Principle of PMMC Instrument: When current carrying conductor is placed in a constant magnetic field, it experiences a force proportional to the current and produces proportional deflection torque. 

Description : State working principle of photo diode. List out its three applications.

Last Answer : Diagram of photo diode :  Working principle of photo diode :  When photons of energy greater than 1.1 eV hit the diode, electron-hole pairs are created. The ... Smoke detector, Optical communication devices, Position sensors, Bar code scanners, Automotive devices, Surveying instruments

Description : Which is the complete specification of the state of the world? a) Atomic event b) Complex event c) Simple event d) None of the mentioned

Last Answer : a) Atomic event

Description : State True or False. 1. Term of reference is the final output of Feasibility Study 2. Design specification report is the final output of System Analysis A) 1-true, 2-true B) 1-false, 2-true C) 1-true, 2-false D) 1-false, 2-false

Last Answer : A) 1-true, 2-true

Description : State important specification parameters of ADC

Last Answer : Accuracy Resolution Linearity Conversion time Settling time stability

Description : State the applications and specification of (i) Resistor (ii) Capacitor (iii)Inductor

Last Answer : Application of resistor: 1.Resistors are used in high frequency instrument. 2.Resistor is used in power control circuit. 3.It is used in DC power supplies. 4.Resistors are used ... DC Current  3.Electromagnetic Interference (EMI)  4.Magnetic Saturation Flux Density  5.Curie Temperature 

Description : working principle of single phase motor

Last Answer : The Stator of single phase induction motor houses two windings  1. Main (Running) winding 2. Auxiliary (Starting ) winding Rotor of single phase induction motor is ... with starting winding or a capacitor may be permanently connected in series with Auxiliary (Starting ) winding.

Description : Describe the working principle of photoelectric pickup type tacho-generator.

Last Answer : Working: Working principle: The light passes through the holes available on the rotating disc with a specific interval, depends on the angular speed of disc having equidistant holes. The frequency of this light pulses ... by N=f/HS  N=speed  f=frequency  Hs=holes on the disc

Description : Which type of flow is measured by hot wire anemometer and describe its working principle with suitable diagram. 

Last Answer : Heat transfer flowmeters this type of flowmeter measures the rise in temperature of the fluid after a known amount of heat has been added to it. Its theory is based upon the specific heat equation ... a supply so as to maintain the wire temperature constant, when the amount of heat transfer varies

Description : With the help of a neat circuit diagram explain the working principle of Digital to Analog converters.(DAC)

Last Answer : Digital-to-Analog Converters:  D/A conversion is the process of converting a value represented in digital code such as binary or BCD into a voltage or current which is proportional ... total of input voltage levels which represents the equivalent analog signals of the 4-bit digital input.

Description : List the types of ADCs. Explain working principle of any one type of ADC.

Last Answer : Types : 1. Successive approximation type A/D converter or Potentiometric type 2.Voltage to time or ramp type A/D converter 3.Voltage to frequency or integrating type A/D converter 4.Dual ... analog voltage and reference voltage are converted to ramp signals of different slopes by the integrator.

Description : Draw and explain the working principle of turbine type flow meter. Mention its Application area.

Last Answer : Working Principle: The flow of liquid past the wheel causes the wheel to rotate at a rate which is proportional to the velocity of the fluid. A voltage pulse is induced in ... Suitable for low viscosity high flow measurements 3) Used in petrochemical industries, in Aerospace applications etc.

Description : Explain in brief the working principle of strain gauge. Define gauge factor and list out types of strain gauges.

Last Answer : If a metal conductor is stretched or compressed, the resistance changes as both length and diameter change. There is a change in the value of resistivity of the conductor also when it is ... metal film strain gauges 6. Diffused metal strain gauges 7. Sputter deposited thin metal strain gauge

Description : Draw and explain the working principle of ultrasonic level measurement system. Also give advantages, disadvantages and applications of it.

Last Answer : Ultrasonic level detectors operate either by the absorption of acoustic energy as it travels from source to receiver or by the attenuation (frequency change) of a vibrating diaphragm face, oscillating at ... without making physical contact with the process material. 2. They have no moving parts.

Description : Explain the working principle of electromagnetic flow meter.

Last Answer : Working Principle: The electromagnetic flow meter uses Faraday's Law of electromagnetic induction to measure the process flow. When an electrically conductive fluid flows in the pipe, an electrode voltage E ... ) The electrode voltage E is directly proportional to the average fluid velocity V.

Description : Explain working principle of bimetallic thermometer.

Last Answer : Working principle: Figure shows construction of bimetallic thermometer, it consists of bimetallic strip usually in the form of a cantilever beam, which is prepared from two thin strips of different ... the thickness of the metal. Pointer is attached to the free end to indicate the temperature

Description : Describe working principle of ultrasonic level detector with diagram.

Last Answer : Working Principle: ultrasonic level detector works on the principle of SONAR. It consists of a ultrasonic transmitter-receiver set mounted on the top of the tank. The beam is projected downward ... 2) Temperature compensation is required 3) The dirt affects the accuracy of the measurement. 

Description : Draw symbol of LED and explain it’s working principle.

Last Answer : Construction of LED: The basic structure of LED is shown in fig.(a). The active region exists between the p and n regions. The light emerges from the active side in all the directions when electron hole-pairs ... fig.(c). In this way an LED emits light. This is the principle of operation of LED.