DickDV
Member
At the risk of adding complexity, there is another type of load out there which increases torque as the speed goes down. Examples would be center-driven winders, center-driven unwinders, and many types of machine tools such as lathes, mills, and drill presses.
These are difficult loads to handle with variable speed because the load behaves exactly opposite of how the motor cooling behaves. A motor with a separate auxiliary cooling system is almost always required for these. The motor hp is also usually much higher than the actual load hp because the motor has to develop high torque at low speed and also high speed for the top speed end. Since the high torque and the high speed never occur at the same time, the motor hp is never fully utilized.
Another tough load to handle is one that cycles constantly from motoring to braking. Stamping presses and oil jacks are examples of these.
While a challenge, they are what makes this field so much fun. Even for an old **** like me! Looking forward to doing this for a few years yet!
These are difficult loads to handle with variable speed because the load behaves exactly opposite of how the motor cooling behaves. A motor with a separate auxiliary cooling system is almost always required for these. The motor hp is also usually much higher than the actual load hp because the motor has to develop high torque at low speed and also high speed for the top speed end. Since the high torque and the high speed never occur at the same time, the motor hp is never fully utilized.
Another tough load to handle is one that cycles constantly from motoring to braking. Stamping presses and oil jacks are examples of these.
While a challenge, they are what makes this field so much fun. Even for an old **** like me! Looking forward to doing this for a few years yet!