Thanks for the clarification Rod (especially as it applied to ADC motors), I know it helped me. Can you or anyone else suggest a text on Sep-ex motors and controllers? Also, has anyone here rewound a series motor for optimization as a sep-ex?
Thanks, Seth Rod Hower wrote: > > Perhaps I should clarify my response. > I don't describe things as well as Lee, but I will > make things more understandable. > When I describe the 'size' of the field winding I am > actually explaining the size of the field winding wire. > What this comes down to is amphere-turns. > The series motor has heavy gage wire that handles > the same current as the armature (hundreds of amps). > If the field has 100 more turns of much smaller gauge wire > it still has effectively the same 'amp turns' as the series motor. > The field only needs to handle 1/100 the amount of current to > create the same field. This is the major advantage of the Sepex > motor, you can electrically reverse and control the field with > a fraction of the amps of a series system. > This also creates a problem, since you can change the dynamics > of the system with 1/100th of the field current. > The series system is somewhat self regulating (as long as you have > a load!). If you don't control the field current properly in a > sepex the system can get destructive real fast. > If you don't believe this, check out the ADC website for > information on motors. If you specify a sepex they want > detailed information about the vehicle and the control. > This is why a sepex motor must be designed with the vehicle, including > gearing, control and load points. > A well engineered sepex in my opinion is much better than a series, but > that depends heavily on a smart engineered vehicle. > You can always drive a poorly designed series system with low range and > efficiency, but if you screw up the sepex design the result could > mean a blown control or efficiency that is even worse than the series > system. > As an example I will compare a Taylor Dunn flat bed vehicle with a load > capacity of 1500lbs. > Series system; > Top speed 24 MPH > Load capacity at moderate grade: 1000 lbs > Sepex system; > Top speed 30 MPH > Load capacity at steep grade: 1500 lbs > I didn't pull these numbers out of the air, I designed the Sepex system > with the same current limit as the series system back in 1995 at GE. > Rod > �
