Question is ⇒ Capacitor in a single-phase induction motor is uscd for, Options are ⇒ (A) improving the power factor., (B) improving the starting torque., (C) starting the motor., (D) reducing the harmonics, (E) , Leave your comments or Download question paper.

Question is ⇒ Capacitor in a single-phase induction motor is uscd for, Options are ⇒ (A) improving the power factor., (B) improving the starting torque., (C) starting the motor., (D) reducing the harmonics, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	Capacitor in a single-phase induction motor is uscd for
A.	improving the power factor. [Wrong Answer]
B.	improving the starting torque. [Wrong Answer]
C.	starting the motor. [Correct Answer]
D.	reducing the harmonics [Wrong Answer]
View Answer 7 -10 Explanation:- Answer : C Discuss it below : !! OOPS Login [Click here] is required to post your answer/result Help other students, write article, leave your comments

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⇒ A 6-pole, 50 Hz wound rotor induction motor when supplied at the rated voltage and frequency with slip-rings open circuited, developed a voltage of 100 V between any two slip rings. If the rotor is driven by an external means at 1,000 rpm opposite to the direction of stator field, the frequency of voltage across slip rings will be
zero.
50 Hz
100 Hz
200 Hz

⇒ In which one of the following is reluctance power developed?
Salient pole alternator.
Non-salient pole alternator.
Squirrel cage induction motor.
Transformer.

⇒ At sub-synchronous speeds. in Kramer system, the electrical power fed to the auxiliary commutator machine at slip frequency is
dissipated as heat.
converted into mechanical power and supplied to the driven shaft.
converted into electrical energy at line frequency and returned back to the supply mains.
none of the above.

⇒ The transformer efficiency at relatively light loads is quite low. This is due to
small copper losses.
small secondary output.
high fixed loss in comparison to the output.
poor power factor.

⇒ The plugging provides ____ braking torque in comparison to rheostatic and regenerative braking systems.
negligible
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highest

⇒ In a single phase induction motor driving a fan load, the reason for having a high resistance rotor is to achieve
low starting torque.
quick acceleration.
high efficiency.
reduced size.

⇒ Which of the following statements associated with shaded pole induction motor is incorrect?
It is one of the simplest and cheapest single phase induction motor.
It has squirrel cage type rotor.
It has high operating efficiency.
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⇒ The losses in a transformer are
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II Eddy current loss
III Hysteresis loss.
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I and II only
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⇒ The torque angle of a synchronous machine operating from a constant voltage bus, is usually defined as the space angle between
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rotor mmf wave and resultant flux density wave.
stator mmf wave and resultant flux density wave.
stator mmf wave and resultant mmf wave.

⇒ In a 3-phase induction regulator, the output line voltages are in phase with the supply line voltage in
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maximum boost position only.
both maximum boost and maximum buck positions.
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⇒ According to maximum power transfer theorem, when is the maximum power absorbed by one network from another network?
The impedance of one of the networks is half that of the other.
The impedance of one is the complex conjugate of the other.
The impedance of one is equal to that of the other.
Only the resistive parts of both are equal.

⇒ Given that D=rotor diameter and L=axial length, a high performance a e servomotor is characterized by
large D,large L
large D, small L
small D, small L
small D, large L

⇒ Laplace transform of the output response of a linear system is the system transfer function when the input is
a step signal
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an impulse signal
a sinusoidal signal.

⇒ Which of the following induction motors will operate on the lowest value of power factor?
7.5 kW, 950 rpm.
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15 kW, 950 rpm
15 kW, 1440 rpm.

⇒ The emf induced in a conductor rotating in a bipolar field is
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ac.
dc and ac both
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⇒ The phenomenon of crawling in a 3-phase induction motor may be due to
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7th space harmonics of air-gap field.
7th time harmonics of voltage wave.
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⇒ The speed of a 4-pole induction motor is controlled by varying the supply frequency while maintaining the ratio of supply voltage to supply frequency (V/f) constant. At rated frequency of 50 Hz and rated voltage of 400 V its speed is 1,440 rpm. Find the speed at 30 Hz, if the load torque is constant.
882 rpm.
864 rpm.
840 rpm
828 rpm.

⇒ The negative phase sequence in a 3-phase synchronous motor exists when the motor is
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overloaded.
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hot.

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open, zero
short, zero
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⇒ If two induction motors A and B are identical except that the airgap of motor 'A' is 50% greater than that of motor 'B' then
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the core losses of A will be more than those of B.
the operating flux of A will be smaller than that of B.

⇒ Where is the Laplace's equation valid?
Only in free space.
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Only in cavities bounded on all sides by conducting walls.

⇒ A 3-phase synchronous motor connected to an infinite bus-bar, with constant excitation, is driving a certain load and operating at leading power factor. If the shaft load is reduced.
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power factor will decrease.

⇒ A 3-phase alternator is wound with a 60 degree phase-spread armature windings and develops 300 kVA. If the armature is reconnected utilizing all the coils for single phase operation with a phase spread of 180 degrees, the new rating of the machine is
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250 kVA
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parallel.
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Concentrated winding in ful pitch coils.
Cncentrated winding in short pitch coils.
Distributed winding in full pitch coils.
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s times
equal to
1/s times
(1 - s) times