A large series motor is never started without some mechanical on it because otherwise it will
A. Produce sparking at brushes.
B. Open fuse or circuit breaker.
C. Draw too much current.
D. Develop excessive speed and damage itself.
Answer: D
Share your understanding of this question with the correct explanation.
The correct answer is D. Develop excessive speed and damage itself.
A large series motor, when started without any mechanical load, has a tendency to accelerate rapidly and reach excessively high speeds. This is because the speed of a series motor is inversely proportional to the torque/load applied to it. Without any mechanical load to resist its rotation, the motor can spin at a dangerously high speed.
Operating the motor at such high speeds can lead to various issues, including excessive wear and tear on the mechanical components, increased friction and heat generation, and potential damage to the motor itself. Therefore, it is necessary to have some mechanical load or resistance on the motor during startup to control its speed and prevent it from reaching unsafe operating conditions.
The other options (producing sparking at brushes, opening fuse or circuit breaker, and drawing too much current) are not the primary concerns associated with starting a large series motor without a mechanical load. While these issues can occur in certain situations, the main concern is the development of excessive speed and the resulting damage to the motor.