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SEE 3433 MESIN ELEKTRIK

SEE 3433 MESIN ELEKTRIK. SYNCHRONOUS MACHINES Basic principles. Field circuit. 3 - Stator terminals. Slip rings. Prime mover. General features. Doubly excited machine. Rotor – field winding – DC current. Stator – Armature winding – AC supply. e.g. operated as a generator.

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SEE 3433 MESIN ELEKTRIK

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  1. SEE 3433 MESIN ELEKTRIK SYNCHRONOUS MACHINESBasic principles

  2. Field circuit 3- Stator terminals Slip rings Prime mover General features Doubly excited machine Rotor – field winding – DC current Stator – Armature winding – AC supply e.g. operated as a generator

  3. Magnetic axis of rotor A B’ C’ Magnetic axis of phase a Stator - Armature - B C • Low speed operation A’ • Large number of poles • e.g. application in • hydroelectric Rotor - field Construction Salient pole If

  4. A Magnetic axis of rotor B’ C’ Magnetic axis of phase a B C • High speed operation A’ • Small number of poles • e.g. application in • steam turbines Construction Cylindrical

  5. Salient rotor

  6. Stator under construction

  7. Synchronous generator – non-salient pole

  8. Frequency of induced voltage given by: Synchronous generators Field current in rotor produce sinusoidal flux in airgap Rotating filed produced when rotor rotates Rotating field induced 3 voltage in 3 phase windings on stator Similar to induction machine, the RMS of induced voltage per phase is Ef = 4.44 f  N Kw Ef known as excitation voltage

  9. Synchronous generators Open circuit characteristic (OCC) Ef depends on: • speed • Flux per pole hance If • Exhibit saturation as flux in core saturated

  10. Synchronous generators Application in power system:

  11. Synchronous motors Stator terminals connected to 3 supply – producing rotating magnetic flux However, rotor won’t be able to rotate or start: Due to inertia, rotor cannot catch-up with the fast rotating field !

  12. Synchronous motors Solved by: 1 Frequency is slowly increased from 0 using power electronics converter

  13. Synchronous motors Solved by: 2 (Damper winding) Rotor has ‘squirrel cage’ construction At synchronous speed no current induced in the winding

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