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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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In a synchronous motor, _________________________ for Under, normal and Over excitation respectively.
A) EbV
B) Eb>V, Eb=V and Eb<V
C) Eb=V, Eb>V and Eb<V
D) Eb=V, EbV
EbV
The correct answer is A: in a synchronous motor, under excitation occurs when Eb<V, normal excitation when Eb=V, and over excitation when Eb>V. These relationships indicate how the internal voltage (Eb) compares to the terminal voltage (V) under different operational conditions.
The correct answer is A: in a synchronous motor, under excitation occurs when Eb<V, normal excitation when Eb=V, and over excitation when Eb>V. These relationships indicate how the internal voltage (Eb) compares to the terminal voltage (V) under different operational conditions.
Eb<V — Under Excitation
Eb=V — Normal Excitation
A synchronous motor operates at a constant speed determined by the supply frequency. Under excitation, the motor draws reactive power from the supply and operates at a lagging power factor; normal excitation results in a unity power factor, while over excitation leads to a leading power factor, thus influencing voltage regulation and stability.
A synchronous motor maintains synchronous speed with its rotor and stator magnetic fields aligned.
The power factor varies with the excitation level, influencing the overall system performance.
High efficiency at rated load.
Ability to operate at unity power factor with proper excitation.
Requires a source for excitation (DC supply).
Limited range of operational speed.
Used in industrial applications for constant speed requirements.
Common in synchronous condensers for power factor correction.
The typical synchronous motor can handle varying loads through excitation adjustments.
Option B is incorrect because it states the wrong order of excitation conditions.
A is correct — the relationships between Eb and V define the motor's operational state.
Understanding the synchronous motor's excitation response is fundamental in power system analysis, especially in stability studies.