Re: (ET) motor controler on EBAY... What do you think

["Monty McGraw" <mmcgraw74 hotmail com>]

This EBAY auction of a Curtis 1205 controller will not work as well as the
Curtis 1244 mentioned in a previous email.  The datasheet for the 1204/1205
controllers is:
http://www.curtisinst.com/datasheets/faxmasters/controllers/1204fax.pdf

The 1205 controller is intended to be used with Series DC motors where the
field is wired in series with the armature.  The GE Electrak's (at least 
the
E15 and E20) use Shunt wound motors, where the field is wired completely
separately from the armature and uses much less current than the armature.
That is why the separately excited Curtis 1244 would be a better match.

We have some Electrak list members that are (or have been) controller
designers that can probably shed more light on the differences in various
solid-state controllers.

I think you may be able to use the 1205 - just wired to the motor armature.
You will need to keep the current Electrak circuit for the field control -
and reverse switching.  I have used a Curtis 1221 higher voltage controller
to replace the original relay switching in my 1981 electric postal van and 
a
series motor and had excellent results - smooth speed control to replace 
the
original multiple switches on a cam jerky speed control.  You will need to
heatsink this controller, and I had to add a fan to blow cool air across
mine to prevent the built-in thermal protection from cutting in.

On my E20 Electrak rebuild project, I'm using a 4QD 300A controller with
regen which is really designed for permanent magnet motors
(http://www.4qd.co.uk/index.html).  To use it with a shunt motor, I'll be
directly connecting the field across the battery pack through a contactor.
The benefit of this controller (or the Curtis 1244) over the 1205 is the
regen braking action.  Also this controller will reverse the armature
current to provide reversing without using reversing contactors.  Built in
safety feature is that throwing the reverse switch input to the controller
while moving forward will first ramp the current down to zero, then reverse
the current to the motor.

I'm still in the midst of the rebuild project and need to complete the rust
removal, priming and painting before beginning to wire up my new design.
I'll keep the list posted as to my success.

Monty McGraw
1988 Pontiac Fiero EV conversion
1981 Comuta-Van electric postal van
197x GE E-20 ElecTrak

----- Original Message -----
From: Paul A. Cianciolo <paulc snet net>
To: Electrak List <elec-trak cosmos5 phy tufts edu>
Sent: Saturday, December 11, 1999 7:16 PM
Subject: (ET) motor controler on EBAY... What do you think


> Hello Folks
> Does anyone have an opinion of this controller?
> I have a 36 volt electric tractor ELECTRAK that I would consider
> changing to this type of controller
>
> Thank    you
>
>
> http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=215781504
> Paulc
> W1VLF
> Cloudbounce Webpage  http://www.qsl.net/w1vlf/
>
> 1986 Vanagon Gas
> 1982 Vanagon Diesel  Turbo Diesel 1.9
> GE Electrak E20 and E15  electric tractors
> First place in local tractor pulls  at 1750 LBS
> With Stock E-20 Electric tractor
>
>
>