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SEE 3433 MESIN ELEKTRIK. SYNCHRONOUS MACHINES - Equivalent circuit - - Phasor diagrams -. Per phase equivalent circuit. Steady state conditions:. Rotor rotates at constant speed. Steady state voltage and current in stator and rotor. Transients will not be considered.
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SEE 3433 MESIN ELEKTRIK SYNCHRONOUS MACHINES- Equivalent circuit -- Phasor diagrams -
Per phase equivalent circuit Steady state conditions: Rotor rotates at constant speed Steady state voltage and current in stator and rotor Transients will not be considered
Excitation voltage, Ef Per phase equivalent circuit Field current in rotor circuit produces sinusoidal distributed flux When rotor rotates, the flux will rotate, f Rotating finduces EMF in stator circuit Current in stator circuit , Ia, produces flux, a Flux that does not link rotor circuit i.e. leakage flux, al Flux that links rotor circuit i.e. Armature reaction flux, ar
Per phase equivalent circuit induces voltage, Ear in the stator circuit arcombines with f producing resultant flux, r r = ar + f In terms of voltages induced, this can be written as: Er = Ear + Ef ar
f r Ef ar Ia Ear Er Per phase equivalent circuit r = ar + f Er = Ear + Ef
f Ear + r + Er f + Ef Ef If ar Ia Ear Er Per phase equivalent circuit r = ar + f Er = Ear + Ef
Ia ar Ear - Ear Per phase equivalent circuit - Ear leads Is by 90o hence can be represented by a voltage across an inductor Er = Ear + Ef Ef = Er Ear Ef = Er + Ia jXar
Ia f If Per phase equivalent circuit - Ear leads Is by 90o hence can be represented by a voltage across an inductor Ef = Er + Ia jXar
f + Er Ear + + Ef If Per phase equivalent circuit - Ear leads Is by 90o hence can be represented by a voltage across an inductor Ef = Er + Ia jXar jXar Ia
jXal Ra f + Er + Ea + Vt If Per phase equivalent circuit - Ear leads Is by 90o hence can be represented by a voltage across an inductor Ef = Er + Ia jXar jXar Ia + Ef The leakage in a is represented by a leakage reactance Xal The stator winding resistance is represented by Ra
jXal Ra f + Er + Ea + Vt If Per phase equivalent circuit In per phase equivalent circuit, Xar and Xal is combined as Xs Xs = Xar + Xal = synchronous reactance jXar jXs + Ea Ia + Ef
jXs Ra Synchronous generator + Vt Ia + Ef Ef Ia jXa Vt IaRa Ia Phasor diagrams Ef= Efo= Vt+ IaRa + IajXs Taking Vtas reference, i.e Vt = Vt 0o Assume Ia lags Vt by angle Is known as the power angle
jXs Ra Synchronous motor + Vt Ia + Ef IaRa Vt Ia Ia jXa Ef Phasor diagrams Vt= Ef+ IaRa + IajXs Ef= Vt- IaRa - IajXs Taking Vtas reference, i.e Vt = Vt 0o Assume Ia lags Vt by angle