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The diameter of the circle diagram is given by
XsтАЛ/VsтАЛ
VsтАЛ/RsтАЛ
VsтАЛ/XsтАЛ
RsтАЛ/XsтАЛ
VsтАЛ/XsтАЛ
In the circle diagram of a polyphase induction motor, the diameter of the circular locus of the stator current is defined by the ratio of the supply voltage to the standstill leakage reactance. This diameter represents the maximum theoretical current that could flow if the motor were operated in a locked-rotor state under ideal conditions.
In the circle diagram of a polyphase induction motor, the diameter of the circular locus of the stator current is defined by the ratio of the supply voltage to the standstill leakage reactance. This diameter represents the maximum theoretical current that could flow if the motor were operated in a locked-rotor state under ideal conditions.
D=XsтАЛVsтАЛтАЛ тАФ represents the diameter of the current locus
IscтАЛ=ZeqтАЛVsтАЛтАЛ тАФ short circuit current magnitude
The circle diagram is a graphical representation derived from the equivalent circuit of an induction motor. By neglecting the magnetizing current and stator impedance, the locus of the stator current vector traces a semicircle. The diameter is geometrically determined by the standstill current phasor, which is proportional to VsтАЛ/XsтАЛ, where VsтАЛ is the phase voltage and XsтАЛ is the total equivalent leakage reactance referred to the stator.
The circle diagram assumes constant supply voltage and frequency.
Stator resistance and magnetizing current are often neglected for simplicity in basic construction.
The diameter is inversely proportional to the standstill leakage reactance.
The circle diagram provides a visual estimate of torque, slip, and power factor.
Provides a quick graphical estimation of motor performance parameters.
Useful for visualizing the relationship between input power, output power, and losses.
Relies on approximations that may lead to inaccuracies in small machines.
Cannot easily account for parameter changes due to saturation.
Performance analysis of induction motors during testing.
Predicting torque-speed characteristics based on no-load and blocked-rotor tests.
The circle diagram is essentially the locus of the stator current phasor as the rotor resistance (variable) changes.
Option D (RsтАЛ/XsтАЛ) represents the tangent of the impedance angle, not the diameter of the current locus.
C is correct тАФ The diameter of the circle diagram for an induction motor is expressed as the ratio of stator phase voltage (VsтАЛ) to the standstill leakage reactance (XsтАЛ).
Always remember that in machine diagrams, the diameter of the current locus is always dominated by the reactance (leakage) rather than resistance because XsтАЛ>>RsтАЛ at standstill.