What is the maximum value of torque angle in electrical degrees for a synchronous motor? 

Explanation:

Maximum Torque Angle in Synchronous Motor

Definition: The torque angle (δ) in a synchronous motor is the angle between the rotor's magnetic field and the stator's magnetic field. This angle is crucial in determining the torque produced by the motor. The torque angle is a critical parameter that affects the motor's stability and performance.

Working Principle: In a synchronous motor, the rotor and the stator have magnetic fields that interact to produce torque. The torque angle (δ) is formed due to the difference in the positions of these magnetic fields. The torque produced in the motor is directly proportional to the sine of the torque angle (T ∝ sin δ). For the motor to operate stably, the torque angle must be within a specific range.

Maximum Torque Angle: The maximum value of the torque angle in electrical degrees for a synchronous motor is 90 degrees. This means that the angle δ can vary from 0 to 90 degrees. Beyond 90 degrees, the motor becomes unstable, and the torque starts to decrease, leading to a potential loss of synchronism. Therefore, the maximum torque angle is crucial for the stable and efficient operation of the motor.

Advantages of Operating Within the Maximum Torque Angle:

• Ensures stable operation of the synchronous motor.
• Optimizes the torque production, ensuring efficient energy conversion.
• Prevents the motor from losing synchronism, which could lead to operational failures.

Disadvantages of Exceeding the Maximum Torque Angle:

• Risk of losing synchronism, leading to motor instability.
• Reduction in torque production, affecting the motor's performance.
• Potential damage to the motor due to unstable operation.

Applications: Synchronous motors are widely used in applications where constant speed is required, such as in industrial machinery, compressors, and conveyors. Maintaining the torque angle within the maximum limit is essential for these applications to ensure reliable and efficient operation.

Correct Option Analysis:

The correct option is:

Option 2: 90

This option correctly represents the maximum value of the torque angle in electrical degrees for a synchronous motor. The torque angle should not exceed 90 degrees to maintain stability and optimal performance of the motor.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: 360

This option is incorrect because a torque angle of 360 degrees is not feasible for synchronous motor operation. The torque angle is defined within a range of 0 to 90 degrees for stable operation. A torque angle of 360 degrees would imply a complete cycle, which is not applicable in this context.

Option 3: 45

This option is incorrect as it represents a possible value within the torque angle range but not the maximum value. The maximum torque angle is 90 degrees, and 45 degrees is just a mid-range value.

Option 4: 180

This option is incorrect because a torque angle of 180 degrees exceeds the stable operating range of the synchronous motor. Beyond 90 degrees, the motor becomes unstable, and 180 degrees would lead to a complete loss of synchronism.

Conclusion:

Understanding the torque angle and its maximum value is essential for the stable and efficient operation of synchronous motors. The maximum torque angle is 90 degrees, beyond which the motor cannot maintain synchronism and becomes unstable. This knowledge is crucial for applications requiring precise and reliable motor performance.