Which of the following statements are true for synchronous motor losses?
A)Friction and windage losses increase with the cube of speed.
B)The Eddy current loss is reduced by laminating the core.
C)Copper losses are independent of load.
D)Core losses increase with the square of the load.

Correct option is A

Friction and windage losses increase with the cube of speed. This statement is true. Friction and windage losses are primarily due to the rotation of the motor's components (such as bearings and rotor). These losses generally increase with the cube of the speed because they are proportional to the rotor's rotational velocity.
The Eddy current loss is reduced by laminating the core. This statement is true. Eddy current losses are caused by circulating currents induced within the conductive core material. Laminating the core reduces the path for these circulating currents, thereby reducing eddy current losses. This is a common method used to improve efficiency in motors.