- Kindly Help To Solve Questions As Below Thank You So Much 1 (77.07 KiB) Viewed 27 times
Kindly help to solve questions as below. Thank you so much
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answerhappygod
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Kindly help to solve questions as below. Thank you so much
Kindly help to solve questions as below. Thank you so much
Question 4 (20 marks) (a) A shunt dc motor has a rated armature current of 20 A, rated (10 marks) field current of 0.5 A, rated voltage of 25 V and maximum rotational speed of 750 rpm. When the rotor is locked, an armature voltage of 1.02 V produces 17 A of current flowing in the armature, while a field voltage of 25 V produces a field current flow of 0.5 A. At no load, with the terminal voltage applied is 24 V, the motor speed is 750 rpm and the current drawn by the motor is 1.32 A. The brush voltage drop is estimated to be 2 V in all conditions. The stray loss is estimated to be 1% of the input power. Determine the output power produced by this motor and the efficiency at the rated conditions. (b) The shunt dc motor in part (a) is now mechanically coupled (10 marks) to a 3-phase synchronous motor, in which the rotational speed of both the shunt dc motor and synchronous motor is 1:1. The synchronous motor is being driven by the shunt de motor, working as a generator. With the shunt dc motor running at 750 rpm, the output frequency of the synchronous motor is 50 Hz. The outputs of the synchronous motor are connected to a balanced 3-phase pure resistive load connected in delta configuration. When the loads are connected to the synchronous motor, the dc shunt motor is running 750 rpm with rated input power and rated voltage. The measured terminal voltage of the synchronous motor is 120 V. Given that the total power losses of the synchronous motor is 15% of the total output power, determine the number of poles of the synchronous motor, the torque experienced at the shaft of the synchronous motor, and the line resistance of the resistive load.
Question 4 (20 marks) (a) A shunt dc motor has a rated armature current of 20 A, rated (10 marks) field current of 0.5 A, rated voltage of 25 V and maximum rotational speed of 750 rpm. When the rotor is locked, an armature voltage of 1.02 V produces 17 A of current flowing in the armature, while a field voltage of 25 V produces a field current flow of 0.5 A. At no load, with the terminal voltage applied is 24 V, the motor speed is 750 rpm and the current drawn by the motor is 1.32 A. The brush voltage drop is estimated to be 2 V in all conditions. The stray loss is estimated to be 1% of the input power. Determine the output power produced by this motor and the efficiency at the rated conditions. (b) The shunt dc motor in part (a) is now mechanically coupled (10 marks) to a 3-phase synchronous motor, in which the rotational speed of both the shunt dc motor and synchronous motor is 1:1. The synchronous motor is being driven by the shunt de motor, working as a generator. With the shunt dc motor running at 750 rpm, the output frequency of the synchronous motor is 50 Hz. The outputs of the synchronous motor are connected to a balanced 3-phase pure resistive load connected in delta configuration. When the loads are connected to the synchronous motor, the dc shunt motor is running 750 rpm with rated input power and rated voltage. The measured terminal voltage of the synchronous motor is 120 V. Given that the total power losses of the synchronous motor is 15% of the total output power, determine the number of poles of the synchronous motor, the torque experienced at the shaft of the synchronous motor, and the line resistance of the resistive load.