Re: (ET) More motor controller questions

["Monty McGraw" <mmcgraw74 hotmail com>]

For Paul's questions,

1. The maximum rating of a controller is only for short periods of time and
the continuous rating is significantly lower than that.  The controllers
current limit for their own protection.  There is no bypass (for full 
power)
relay in either controller.  The Electric Vehicle discussion list has
several postings for folks that have talked about, or tried to bypass their
electronic controllers for maximum acceleration.  A relay certainly beats
the electronics on this matter.

2. You will need to provide cooling to the controller to get the most
current for long periods. You really need to look at the manufacturer's
specs to tell.  I put links to Curtis controller specs and 4QD specs in one
of my previous posts.

Monty McGraw

----- Original Message -----
From: Paul A. Cianciolo <paulc snet net>
To: Electrak List <elec-trak cosmos5 phy tufts edu>
Sent: Wednesday, December 15, 1999 4:36 AM
Subject: (ET) More motor controller questions


> Hello FOlks,
>
> I have received a lot of good info about controllers and where to find
them
> relatively
> inexspensive rebuilds.  Golftech, and others.
>
> I have 2 questions
>
> 1) When a controller is purchased that is supposed to handle say 48 Volts
at
> 300 amps
> what happens when the demand is greater than that?   Is this current
limited
> by the controller or does it burn out?  Also is there a bypass relay
> internal to controllers that "short" the fet devices under full current ?
>
>
> 2)  Are controllers rated at particular duty cycle?  As in the above
> controller... could it do 300 amps all day long
> or is that a peak current for only a few seconds and it can run at say
half
> of that long term?
>