Re: Enable Circuit...How it Works

[David Volkenand <CTVN@NETW.COM>]

John Wayland wrote:
>       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.


> Bill Dube' wrote:
>         On a Curtis, If you wire the enable directly to V+ the controller
> will start up even if the throttle is wide open. If you don't use the switch
> in the pot box to break the enable circuit at zero throttle, there is no
> protection from a "launch" when you close the contactor. For the safety
> feature to work correctly, the sequence (in a Curtis) must be: 1) enable
> off, 2) precharge, 3) contactor closed, 4) throttle at zero position, 5)
> enable on.

     I don't agree with this. I have seen curtis controllers go into
high pedal disable when the the enable was tied to V+ and not going thru
a microswitch. The Curtis manual says that the controller looks for a
high throttle position after a delay after the cotroller is turned on.
So it should not matter if the enable is tied directly to V+ and in my
experience, it doesn't. The High pedal disable still functions. I do
think it is a good idea to use the potbox microswitch, though.



>  If for some reason, a wire from the pot came
> loose, or the pot was defective and was at high resistance while the
> pedal was in the rest position, as soon as the pedal was partially or
> even completely depressed and the enable switch closed, the 'High Pot
> Lockout' would keep the controller from turning on.
>      I hope this helps clear things up.

The open potbox wire protection is different than the high pedal
disable.

David
Re: Enable Circuit...How it Works