GATE EE 2025 Set 1 — Question 35
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Electrical Machines → Synchronous Machines → Synchronizing Power & Power Angle
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Question
The induced emf in a , pole, -phase star connected synchronous motor is considered to be equal and in phase with the terminal voltage under no load condition. On application of a mechanical load, the induced emf phasor is deflected by an angle of mechanical with respect to the terminal voltage phasor. If the synchronous reactance is , and stator resistance is negligible, then the motor armature current magnitude, in ampere, during loaded condition is closest to, ____________ (round off to two decimal places).
Correct answer
66.25 to 66.75
Solution
Given:
Line voltage,
Phase voltage for star connection,
Number of poles,
Mechanical deflection angle,
Electrical deflection angle,
Synchronous reactance,
Stator resistance, At no load, the induced emf is equal to and in phase with the terminal voltage . Thus, .Under loaded condition, the induced emf phasor is deflected by . In a motor, lags by the load angle .
Taking as the reference:
The armature current is calculated as:
The magnitude of the armature current is:
Since :
Rounding off to two decimal places, the armature current magnitude is .
Line voltage,
Phase voltage for star connection,
Number of poles,
Mechanical deflection angle,
Electrical deflection angle,
Synchronous reactance,
Stator resistance, At no load, the induced emf is equal to and in phase with the terminal voltage . Thus, .Under loaded condition, the induced emf phasor is deflected by . In a motor, lags by the load angle .
Taking as the reference:
The armature current is calculated as:
The magnitude of the armature current is:
Since :
Rounding off to two decimal places, the armature current magnitude is .
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