MCQOPTIONS
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MCQOPTIONS
This section includes 3 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. |
Consider a 3-phase alternator with negligible armature resistance and high rotational inertia delivering power to an isolated load when the armature terminals got short circuited. After sometime, the mechanical power input to the shaft of the machine is terminated at time t0. The short-circuit current circulating in the armature will change till the machine comes to halt at ‘ts’. Which one of the curves depicts this phenomena? |
| A. | a) |
| B. | b) |
| C. | c) |
| D. | d) |
| Answer» B. b) | |
| 2. |
The phasor diagram of a synchronous machine connected to an infinite bus is shown in the figure. |
| A. | The machine is acting as |
| B. | generator and operating at leading pf |
| C. | generator and operating at lagging pf |
| D. | motor and operating at leading pf |
| E. | motor and operating at lagging pf |
| Answer» B. generator and operating at leading pf | |
| 3. |
When a 3–phase alternator is suddenly short–circuited at its terminals, the initial value of the short–circuit current is limited by which one of the following? |
| A. | x”d |
| B. | x’d |
| C. | xs |
| D. | Sum of x”d, x’d and xs |
| Answer» B. x’d | |