Question
Download Solution PDFLet ϕ be the phase angle between the line current and line voltage, and α be the load angle. The per phase mechanical power developed by a synchronous motor is:
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFV = Terminal phase voltage applied to the armature (V)
Ia = Armature current/phase (A)
Eb = Back EMF to the motor (V)
Ra = Armature resistance/phase (Ω)
Xs = Synchronous reactance/phase (Ω)
Zs = Impedance/phase (Ω)
ϕ = Phase angle between line current and line voltage.
α = Load angle (Load angle = Angle between Back EMF and terminal voltage)
Zs = Ra + j Xs = j Xs (as resistance is very small so neglected)
Power input to the motor (P) = V × Ia × cos ϕ W per phase
From the phasor
AB = Eb sin α = Ia Xs cos ϕ
Mechanical losses are neglected then Input electrical power = Mechanical power developed
∴ Per phase developed Mechanical power is
Important Points
Power stages in a Synchronous motor
Last updated on Jul 1, 2025
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