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

14 views
by
Explain the concept of initial and final conditions in switching for L and C.

Your answer

Thanks for your contribution. Feel free to answer this question. Please avoid short answer. Your answer is most welcome. Be genuine.

Upload image or document:

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
Are you a robot ? (Y = Yes / N = No)
To avoid this verification in future, please log in or register.

1 Answer

0 votes
by

i) Inductor: The current through an inductor cannot change instantly. If the inductor current is zero just before switching, then whatever may be the applied voltage, just after switching the inductor current will remain zero. i.e the inductor must be acting as open-circuit at instant t = 0. If the inductor current is I0 before switching, then just after switching the inductor current will remain same as I0, and having stored energy hence it is represented by a current source of value I0 in parallel with open circuit. As time passes the inductor current slowly rises and finally it becomes constant. Therefore the voltage across the inductor falls to zero [vL=LdiL/dt=0]. The presence of current with zero voltage exhibits short circuit condition. Therefore, under steady-state constant current condition, the inductor is represented by a short circuit. If the initial inductor current is non-zero I0, making it as energy source, then finally inductor is represented by current source I0 in parallel with a short circuit.

ii) Capacitor: The voltage across capacitor cannot change instantly. If the capacitor voltage is zero initially just before switching, then whatever may be the current flowing, just after switching the capacitor voltage will remain zero. i.e the capacitor must be acting as short-circuit at instant t = 0. If capacitor is previously charged to some voltage V0, then also after switching at t = 0, the voltage across capacitor remains same V0. Since the energy is stored in the capacitor, it is represented by a voltage source V0 in series with short-circuit. As time passes the capacitor voltage slowly rises and finally it becomes constant. Therefore the current through the capacitor falls to zero[iC=CdvC/dt=0]. The presence of voltage with zero current exhibits open circuit condition. Therefore, under steady-state constant voltage condition, the capacitor is represented by a open circuit. If the initial capacitor voltage is non-zero V0, making it as energy source, then finally capacitor is represented by voltage source V0 in series with an open-circuit. 

The initial and final conditions are summarized in following table:

image

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.

Categories

Most popular tags

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