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Following statements are given for DC motors (a) DC motors require less maintenance than AC motors (b) DC motors cannot provide high starting torque (c) DC motors are not suitable for very high-speed applications (d) The methods of speed control of DC motors are simpler and less expensive than those of AC motors Which of the following statements are correct?
Consider the following statements regarding ac drives: 1. For the same kW rating, ac motors are 20% to 40% light weight as compared to dc motors. 2. The ac motors are more expensive as compared to same kW rating dc motors. 3. The ac motors have low maintenance as compared to dc motors. Which of the above statements are correct?
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. An external resistance is now tripled in the rotor circuit. Then the slip at which maximum torque occur for the same load torque is?
For a three phase induction motor, maximum torque is double the full load torque and starting torque is 1.6 times the full load torque. To get a full load slip of 5%, percentage reduction in the rotor resistance should be?
In a survey of 100 students, it was found that 25 students have enrolled for Navy AA test series, 26 students have enrolled for NDA test series, 26 students have enrolled for Airforce group X test series, 9 students have enrolled for both Navy AA and Airforce group X test series, 11 students have enrolled for both Navy AA and NDA test series, 8 students have enrolled for both NDA and Airforce group X test series whereas 3 students have enrolled in all three test series. Find the number of students who have enrolled exactly in any two test series.
Which of the following statements are correct for an ideal constant voltage source? 1. Its output voltage remains absolutely constant whatever the change in load current. 2. It possesses zero internal resistance so that internal voltage drop in the source is zero. 3. Output voltage is provided by the source would remain constant irrespective of the amount of current drawn from it. 4. Output voltage provided by the source varies with the amount of current drawn from it.
In a survey of 100 students, it was found that 25 students have enrolled for Navy AA test series, 26 students have enrolled for NDA test series, 26 students have enrolled for Airforce group X test series, 9 students have enrolled for both Navy AA and Airforce group X test series, 11 students have enrolled for both Navy AA and NDA test series, 8 students have enrolled for both NDA and Airforce group X test series whereas 3 students have enrolled in all three test series. Find the number of students who has not enrolled in any of the test series.
In a survey of 100 students, it was found that 25 students have enrolled for Navy AA test series, 26 students have enrolled for NDA test series, 26 students have enrolled for Airforce group X test series, 9 students have enrolled for both Navy AA and Airforce group X test series, 11 students have enrolled for both Navy AA and NDA test series, 8 students have enrolled for both NDA and Airforce group X test series whereas 3 students have enrolled in all three test series. Find the number of students who have enrolled in exactly one test series.
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque equal to twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. The slip at the full load torque will be?
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. The speed at the full load torque will be?