Question
Download Solution PDFAn under excited synchronous motor operates at ________ power factor.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
Synchronous motor:
V curves for synchronous motor give the relation between armature current and field current. The curves are shown below.
A synchronous motor is capable of operating at all types of power factor i.e. either UPF, leading, or lagging power factor.
- Lagging power factor: If field excitation is such that Eb < V the motor is said to be under-excited and it has a lagging power factor.
- Leading power factor: If field excitation is such that Eb > V the motor is said to be over-excited and it draws leading current. So that the power factor improves.
- Unity power factor: If field excitation is such that Eb = V the motor is said to be normally excited.
Synchronous generator:
A synchronous generator or alternator is capable of operating at all types of power factors i.e. either UPF, leading, or lagging power factor.
- Leading power factor: If field excitation is such that Eb < V the alternator is said to be under-excited and it has a leading power factor.
- Lagging power factor: If field excitation is such that Eb > V the alternator is said to be over-excited and has a lagging power factor.
- Unity power factor: If field excitation is such that Eb = V the alternator is said to be normally excited.
- V -curve for synchronous generator or alternator is shown below
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