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ElectricalMachine
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The rotor copper losses of the synchronous motor is met by

A

Armature input

B

Ac supply mains

C

Dc source

D

All of these

Correct Answer

тЪЩя╕П TE тАв Technical Concept & PrincipleElectricalMachine
Option C

Dc source

Quick Summary:

The rotor copper losses in a synchronous motor are primarily met by a DC source, which provides the necessary excitation to the rotor, enabling it to maintain synchronism with the rotating magnetic field ┬╖ This is essential for the motor's operation and efficiency.

тЪЩя╕ПTETechnical SolutionConcept & Principle
ЁЯТб Explanation

The rotor copper losses in a synchronous motor are primarily met by a DC source, which provides the necessary excitation to the rotor, enabling it to maintain synchronism with the rotating magnetic field ┬╖ This is essential for the motor's operation and efficiency.

ЁЯФв Key Formulas

Ploss=I2RP_{loss} = I^2 RPlossтАЛ=I2R тАФ Copper loss in the rotor

E=VтЛЕIтИЧE = V \cdot I^*E=VтЛЕIтИЧ тАФ Effective power equation

тЪЩя╕П Working Principle

In a synchronous motor, the rotor is supplied with direct current through slip rings, which generates a magnetic field ┬╖ This magnetic field interacts with the stator's rotating magnetic field, causing the rotor to turn at synchronous speed ┬╖ The copper losses, which are the result of resistance in the rotor winding, are compensated for by this DC excitation, ensuring effective performance.

ЁЯУМ Key Points
  • тЦ╕

    Rotor copper losses occur due to the resistance of the rotor windings when current flows through them.

  • тЦ╕

    Maintaining a consistent DC supply is crucial for synchronous operation and minimizing losses.

тЬЕ Advantages
  • тЦ╕

    Stable operation at synchronous speed.

  • тЦ╕

    High efficiency due to low slip.

тЭМ Disadvantages / Limitations
  • тЦ╕

    Requires a DC source for excitation.

  • тЦ╕

    Complex control system needed for varying loads.

ЁЯЫая╕П Applications / Uses
  • тЦ╕

    Used in synchronous generators for power plants.

  • тЦ╕

    Applicable in elevating systems and industrial drives.

ЁЯУД Additional Information
  • тЦ╕

    Standard excitation voltage ranges for synchronous motors are typically between 120V to 250V.

  • тЦ╕

    Option A is incorrect because armature input does not directly compensate for copper losses; rather, it contributes to overall power input.

ЁЯУК Diagram / Illustration
Synchronous Motor OperationDC SourceRotorExcitation
тЬЕ

C is correct тАФ The rotor copper losses of a synchronous motor are compensated by the DC source which provides necessary excitation.

Core Concepts Used
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Synchronous motor operation Copper losses in windings Importance of rotor excitation
ЁЯТб EXAM TIP

Understand the role of excitation in the operation of synchronous motors, as this concept also applies to synchronous generators.

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