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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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Capacitor start and run 1-phase IM is basically a
ph induction motor
ph induction motor
ph reluctance induction motor
ph induction motor
ph induction motor
A capacitor start and run induction motor is a single-phase induction motor that utilizes two capacitors—one for starting and one for running—to improve torque characteristics and power factor. Despite using these capacitors to create a phase shift, it remains fundamentally a single-phase induction motor as it operates from a single-phase AC supply.
A capacitor start and run induction motor is a single-phase induction motor that utilizes two capacitors—one for starting and one for running—to improve torque characteristics and power factor. Despite using these capacitors to create a phase shift, it remains fundamentally a single-phase induction motor as it operates from a single-phase AC supply.
Tst∝ImIasinθ
θ=tan−1(RaXc)
The stator contains two windings: a main winding and an auxiliary (starting) winding. A capacitor connected in series with the auxiliary winding causes the current in that winding to lead the current in the main winding, creating a rotating magnetic field necessary for starting. During running, a smaller permanent capacitor remains in the circuit to maintain higher efficiency and smoother torque, mimicking a two-phase system behavior while powered by a single-phase source.
Uses a centrifugal switch to disconnect the start capacitor after reaching 75% speed.
The run capacitor remains permanently in the circuit to improve power factor and efficiency.
Provides high starting torque compared to resistance-split phase motors.
Operates quietly due to better balanced flux distribution.
High starting torque
Improved power factor during operation
High efficiency
Smooth running with less vibration
Expensive due to two capacitors and a centrifugal switch
Increased maintenance due to the centrifugal switch
Refrigerators
Compressors
Conveyors
Large capacity fans
The motor is often called a 'two-value capacitor motor'.
Option B is wrong because even though the auxiliary winding provides a 90-degree phase shift, the source remains single-phase.
Option D is wrong because a 3-phase motor requires a 3-phase supply and produces a balanced rotating magnetic field naturally.
A is correct — The capacitor start and run motor is a single-phase induction motor that uses capacitors to approximate a two-phase supply for improved starting and running performance.
Always remember that in single-phase machines, 'phase' refers to the supply input, not the internal winding configurations or auxiliary circuits.