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

["Dave & Deb" <daveb drizzle com>]

I think my first 3 failures were bad from the factory.  Steve Richardson
told me that some of the internals were too close together in the first
batch or two and were overheating to the point of smoking out.  that was
the symptom exactly of my second units failure.  my first unit may have
been my fault because I left the varistor (MOV) between the field wires...
 The third unit smoked in a similar way to the second and it's serial
number was in the range of the early runs that had the overheat problem. 
It didn't smoke itself until I flipped the PTO on though...  The fourth
one is still in the box until I get the time and courage to try again ;^)


Dave

> 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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