Which one of the following devices can be used to accurately and conveniently measure the speed of a motor with a small slip? A. Tachometer B. Revolution counter and stop watch C. Incandescent lamp and colored disk D. Stroboscope
Which one of the following devices can be used to accurately and conveniently measure the speed of a
motor with a small slip?
A. Tachometer
B. Revolution counter and stop watch
C. Incandescent lamp and colored disk
D. Stroboscope
Note: I have doubts if it is the letter A or the letter D, can you help me in this question, thanks.
To measure the speed of the motor, the commonly used device is the tachometer due to the inaccuracies associated with the stopwatch the Revolution counter and stopwatch for measuring the high speed is not preferred.
For the motors with small slip (asynchronous motor), the measurement that is shown by the tachometer is less accurate and the accuracy keeps on decreasing as the value of slip decreases. Since the tachometer requires power to run and it is powered from the device is to be measured thus it is also not preferred for the fractional horsepower motors.
Incandescent lamps and colored disks are used as calibrating devices and they cannot be used to measure the speed of the motor alone without using other devices in conjunction.
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