1/2 hour rated motors are used for
1/2 hour rated motors are used for
Right Answer is:
Medium duty cranes
SOLUTION
- An essential requirement of a Medium duty crane motor is to develop a high starting tot and should be able to withstand a medium number of switching operations.
- Besides, these motors are provided with special electro-mechanical brakes, which by means of springs, are made to hold the load as soon as the supply fails.
- On the restoration of supply, the solenoid across the terminals of the motor gets energized and brakes are released. Such motors are 1/2 hr or one hour rated.
- Interestingly the term short time rating is defined as:– The output which a motor can give for a specified period (e.g. 1 hr, 1/2 hr, etc.) without exceeding a specified temperature, the motor is assumed to be the short-time rated motor.