Welcome to electrical and electronics engineering Q&A site...

Welcome to electrical and electronics engineering discussion website, Please login or register to continue.

Join our WhatsApp group

Subscribe To Our YouTube Channel

Draw and explain the displacement measurement system using LVDT.

Amazon Shopping

Please log in or register to answer this question.

1 Answer

0 votes




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.

Working: Case I: When there is no displacement. When no displacement is applied to the core, the core is at normal position. The flux linking with both the secondary windings is equal. Equal e.m.f. is induced in both secondary windings or VS1=VS2 So, Vo = VS1 -VS2 = 0 The output voltage Vo at null position is zero. 

Case II: When the core moves to the left due to some displacement: When the core is moved to left of null position due to some displacement applied, more flux links with winding S1 than winding S2 Hence e.m.f. induced in S1 is greater than the e.m.f. in S2, that is VS1>VS2 The output voltage Vo = VS1-VS2 and is in phase with the input primary voltage.

Case III: When the core moves to the right due to some displacement: When the core is moved to right of null position due to applied displacement, more flux links with winding S2 than winding S1. So e.m.f. induced with winding S2 is greater than S1.that is VS2>VS1 Hence the output voltage Vo= VS1-VS2 and is 1800 out of phase with the input primary voltage. In this way any physical displacement of core causes the voltage of one secondary winding to increase while simultaneously reducing the voltage in the other winding. Output voltage Vo measured is equivalent to the displacement.

Amazon Shopping

Welcome to Q&A site for electrical and electronics engineering discussion for diploma, B.E./B.Tech, M.E./M.Tech, & PhD study.
If you have a new question please ask in English.
If you want to help this community answer these questions.


Most popular tags

power motor dc circuit transformer voltage current used system phase factor resistance load synchronous energy ac induction generator electric series frequency capacitor use speed between electrical meter line type mosfet control transmission difference magnetic plant high single instrument bjt source advantages function diode machine unit winding torque amplifier define supply thyristor motors arduino field shunt maximum relay armature problem electricity time parallel on transformers types coil diagram state flow value material three starting and direction theorem method emf operating digital microprocessor test instruments efficiency ratio loss measure operation connected low applications wave effect single-phase working losses different network wattmeter temperature measuring constant signal controlled breaker device full compare drive wire resistivity logic materials machines inductance switch flux disadvantages converter transistor gain protection scr angle force core measurement number free principle rc generators law negative bridge friction open pole conductor conservation steam iron loop resistors hysteresis short computer circuits using lines secondary station battery rectifier inverter linear relays nuclear regulation reactance design analog work rotor electronics gate forces diesel damping rlc connection factors capacitors minimum insulation basic moving running systems air fault range direct main stability quality starter igbt eddy ideal ammeter rl 3-phase plants arc induced thermal error fuzzy biasing dielectric pressure balanced superposition errors rotation characteristics feedback measured electronic start alternator off back curve over solar three-phase tariff locomotive peak bias zener capacitance commutator surge rating universal potentiometer permanent mechanical copper self transducer capacity electrons memory adc excitation inductive transfer explain fuse pure harmonics application inductor internal pmmc average reaction welding resonance traction breakers designed electromagnetic si generation brushes density switching shaded rate impedance distribution methods star oscillator reluctance semiconductor simplification algebra 8085 boolean weston dynamometer insulating strength installation permeability definition fuel heating earth units neutral rms rated engineering conductors coefficient controller usually reverse excited analysis change body components