motor stalling

[Conjuror]

Should design b motors be operated in parallel with a variable load process like a large wood chipper that eats whole trees in 10 seconds or less? Wouldn't design d motors speed vs. torque characteristics perform better in sharing the load equally as the torque requirement increased and the slip started to increase?

 

[jraef]

Generally, chippers work on the inertia of the chipper head mass, not the direct HP of the motor connected to it. The motor is there primarily to recover speed of the chipper head after the log absorbs that kinetic energy. Increasing torque at that point beyond what is required for re-acceleration becomes wasted for the most part and can turn into heat in the windings. Design B motors actually work better for that because the mass can only re-accelerate at a given rate anyway without adding massive amounts on extra HP.

Operating motors in parallel has other challenges, but for the most part as long as both motors are exactly the same, it's not a big problem. Machine designers use this concept all the time with excellent success.

"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more."
Nikola Tesla

 

[raisinbran]

Conjuror,
We use crushers to crush coal/rock as we mine it. As Jraef said - you rely mostly on the mass of the crushing/chipping head todo the actual work. We use design C motor(s) connected to a fluid coupler which is then connected to a gear reducer, which is connected to the impact wheel. The fluid coupler: allows the motor to start at no load: allows the motor to re-accelerate the impact wheel using motor breakdown torque levels, and mechanically disconnects the motor from the impact wheel should the wheel become jammed. This last point serves to isolate the motor inertia from the gearing rather than tear up the gearing.
Raisinbran