RE: (ET) RE: Alltrax DCX300 availability - Field current

[Rod Hower <rodhower ameritech net>]

What does the ET shunt field draw (or more
specifically how much field current flows in the
E15?).
My E15 has a compound wound motor and from a control
design point is not as difficult to prevent blow ups
compared to a full sepex motor.  The biggest problem
with a motor like this is what happens during a
reverse command.  If you don't let the field current
decay before reversing, the armature current can be
quite high, even with a compound motor, I wonder if
this was the problem?  For background info I designed
a compound wound control for a Caterpillar forklift
back in the early 90's.  If I didn't allow sufficient
time for the shunt field to decay there was a huge
current spike.
It would be interesting to hear what problems caused
control failures in the Alltrax.
Rod

--- Markus Lorch <mlorch vt edu> wrote:

> 
> 
> > 
> > >From what I understand, the ET model has
> additional current sensing 
> > circuitry for the field controller.  The ET's
> motor wants a 
> > much lower field 
> > current than a typical separately excited field
> golf car 
> > motor, something like 
> > one-tenth.
> 
> Yes, I think I was wrong and they had to make some
> (minor, but
> manual) hardware modifications. Plus they also
> developed a different field 
> map which Steve R. posted to the list a while ago.
> So the ET version is
> basically a customized, low-volume product.
> 
> I have gotten info on the (inexpensive) SPX
> controllers that "look like"
> the DCP controllers we would need from Jeff @
> Alltrax. It turns out these
> were DCP controllers that had a problem with a bad
> component in the field
> control circuit and thus were converted by Alltrax
> to standard controllers 
> for series wound or PM motors. 
> 
> Markus
> 
> 
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