Re: Enable Circuit...How it Works

["Bill Dube'" <bdube@BOULDER.NIST.GOV>]

>      Both the Curtis and the Auburn controllers have these enable
>circuits. Both controllers can simply have the enable circuit tied to
>the controller positive input connection, and the controller will turn
>on as soon as the main contactor closes. However, by doing this, you
>disable an important safety feature known as  'High Pot Lockout'.

>Without the 'High Pot Lockout' engaged, if there is a foot on the pedal,
>or if the pot box is anything higher than zero ohms when the contactor
>closes, the EV's motor will suddenly start running.....not a good thing!
>By closing the enable circuit after the contactor has closed, the 'High
>Pot Lockout' is in full effect, and could help prevent a
>disaster....even save a life! When the 'High Pot Lockout' is in engaged,
>if the enable circuit is closed while the pot box is at a resistance
>higher than zero ohms, the controller will not operate.

         "Hot wiring" the enable on a Curtis does exactly this. On an
Auburn, however, if the controller wakes up with more than about 10%
throttle, it will not turn on. The Auburn does this regardless of whether
the enable is wired directly to V+ or is connected to V+ after the
controller wakes up. An Auburn will possibly "lurch" but won't "launch."

        The term "High Pot Lockout" refers to the condition when the signal
from the throttle pot indicates much more than 5,000 ohms. This is likely a
broken wire and thus the controller shut off and waits for the pot
resistance to go to a value less than aproximately 10 % throttle (in an
Aurburn.)

         I'm not 100% sure, but I think the Curtis wants to see the Enable
line go off, then on, to reset the high-pot lockout.

        I think the term for the condition that occurs when you attempt
energize the controller with greater than 10% throttle is something like
"Partial Throttle Start-Up" or some such.






             _   /|
             \'o.O'              Bill Dube'
           =(___)=           bdube@boulder.nist.gov
              U

Re: Enable Circuit...How it Works