Assertion (A): Servomotors have heavier rotors and lower R/X ratio as ...
Explanation: Ac servomotors are essentially induction motor with low X/R ratio for the rotor which has very low inertia.
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Assertion (A): Servomotors have heavier rotors and lower R/X ratio as ...
Assertion (A): Servomotors have heavier rotors and lower R/X ratio as compared to ordinary motors of similar ratings.
Reason (R): Servomotor should have smaller electrical and mechanical time constants for faster response.
Explanation:
The given assertion states that servomotors have heavier rotors and lower R/X ratio compared to ordinary motors of similar ratings. The reason provided is that servomotors should have smaller electrical and mechanical time constants for faster response.
Understanding Servomotors:
- Servomotors are specialized motors designed for precise control of position, speed, and acceleration.
- They are commonly used in applications such as robotics, CNC machines, and automation systems.
- Servomotors provide high levels of accuracy, speed, and torque control, making them suitable for applications that require precise and rapid movements.
Heavier Rotors and Lower R/X Ratio:
- In order to achieve faster response and better control, servomotors are designed with certain characteristics different from ordinary motors.
- The rotor of a servomotor is typically heavier compared to an ordinary motor.
- The heavier rotor helps in providing better inertia, allowing the motor to quickly respond to changes in speed and position.
- This is especially important in applications where rapid acceleration and deceleration are required.
- The R/X ratio is the ratio of the resistance (R) to the reactance (X) of the motor.
- In servomotors, the R/X ratio is lower compared to ordinary motors.
- This is because a lower R/X ratio implies a higher reactance, which helps in reducing the electrical time constant of the motor.
- The electrical time constant represents the rate at which the current in the motor windings changes in response to a voltage change.
- By reducing the electrical time constant, servomotors can respond more quickly to changes in input signals, resulting in faster and more accurate control.
Evaluation of the Assertion and Reason:
- The assertion states the characteristics of servomotors (heavier rotors and lower R/X ratio) correctly.
- However, the reason provided does not correctly explain why servomotors have heavier rotors and lower R/X ratio.
- The reason suggests that servomotors have smaller electrical and mechanical time constants for faster response, but it does not directly explain why heavier rotors and lower R/X ratio are required for achieving smaller time constants.
Conclusion:
- In conclusion, the assertion (A) is true as servomotors do have heavier rotors and lower R/X ratio.
- However, the reason (R) is false as it does not correctly explain why servomotors have these characteristics.
- Hence, the correct answer is option 'D' - A is false but R is true.
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