MCQOPTIONS
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MCQOPTIONS
This section includes 6 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines Questions and Answers knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
For the below graph depicting the performance of a synchronous motor, coordinates ‘x’ and ‘y’ are respectively? |
| A. | In the ‘V’ curve shown in the above figure for a synchronous motor, the parameter of x and y coordinates are, respectively. |
| B. | Armature current and field current |
| C. | Power factor and field current |
| D. | Armature current and torque |
| E. | Torque and field current |
| Answer» B. Armature current and field current | |
| 2. |
The operating point for an over excited alternator working near zpf lagging power factor gives ‘A’ as the operating point. Then if the same machine is working as an over excited synchronous motor will give same operating point at __________ |
| A. | zpf leading |
| B. | zpf lagging |
| C. | upf |
| D. | there will never be the same operating point for the machine as motor as well as generator |
| Answer» B. zpf lagging | |
| 3. |
In the figure below, the point ‘F’ corresponds to _______ which can be obtained by ________ |
| A. | field current required to circulate short circuit current, SCC |
| B. | field current required to circulate full load current, SCC |
| C. | mmf required to cancel the hysteresis losses, SCC |
| D. | mmf required to compensate the leakage reactances, SCC |
| Answer» B. field current required to circulate full load current, SCC | |
| 4. |
From the figure shown below for the OCC and SCC of a three phase alternator, the point ‘L’ corresponds to _______ and the point ‘A’ can be obtained by _____ the alternator. |
| A. | terminal voltage, over exciting |
| B. | excitation voltage, over exciting |
| C. | terminal voltage, under exciting |
| D. | excitation voltage, under exciting |
| Answer» B. excitation voltage, over exciting | |
| 5. |
A 420 V synchronous motor is working at 30° lagging load. What can be the expected phasor? |
| A. | a) |
| B. | b) |
| C. | c) |
| D. | None of the mentioned |
| Answer» B. b) | |
| 6. |
Below is the phasor diagram of synchronous generator. |
| A. | If the machine is made to run as synchronous motor, what will be the phasor diagram changes then? |
| B. | Reverse Ia |
| C. | Reverse Ef |
| D. | Reverse Vt and Ia |
| E. | Reverse Vt |
| Answer» B. Reverse Ia | |