Re: (ET) Alltrax finally up and running!

[Rod Hower <rodhower ameritech net>]

If the field connection has an open, armature current
will be excessive and possibly blow the control
(although it should not if the current limit circuitry
is designed properly, even on a dead short, but this
depends on how current limit is implemented on the
control.  Sometimes the current limit circuit is
designed to prevent high current on a 'good' motor but
necessarily for a motor that has a shorted winding, or
open winding in the case of a compound wound/shunt
wound motor).  The other posibility is a shorted shunt
field.  In this case the H-bridge shunt field MOSFET's
could blow up and possibly the armature MOSFET's as
well.  A high voltage error could be caused from
excessive voltage seen while turning of the MOSFET's
(stray inductance and very high currents can cause
nasty voltage spikes).  I'm just speculating and don't
know how this control was designed.  I do know that
similar failures occured on GE controls while I worked
there from 1991-1994 designing various low voltage
golf cart and electric greensmower controls that
operated on 36 and 48V.
If your motor is running slow and drawing excessive
current I would speculate that you have a shorted
winding in the field or armature.  The short could
appear anywhere in the winding giving you extreme
field weakening and making the motor very
innefficient.
Good luck on the trouble-shooting!
Rod

--- David Roden <etpost drmm net> wrote:

> On 6 Sep 2006 at 13:21, Kleinbrahm, Robert wrote:
> 
> > I discovered that
> > when I checked continuity from the field motor
> connections F1 & F2 back
> > to the controller leads they seemed to be fine.  I
> then took it one step
> > farther and actually disconnected the J6
> connectors and retested for
> > continuity.  It was then that I discovered that
> the connector output
> > lead for pin # 36 had 2 wires coming out of it,
> even though the input
> > side only had 1 wire.  I made the mistake of
> connecting both leads from
> > this pin out source to the F1 & F2 field
> connections on the controller
> > unit. 
> 
> I don't understand what you mean by "the connector
> output lead for pin #36 
> had 2 wires coming out of it, even though the input
> side only had 1 wire."  
> What is pin #36?  How can a connector have an input
> and an output?  Sorry, I 
> guess I'm just not picking up on your nomenclature
> here.
> 
> Are you saying that you connected the Alltrax field
> outputs to the same 
> terminal?  If so, that would sort of explain why
> four of them failed.  A 
> short circuit on the field output is generally
> fatal.  
> 
> Or are you saying that one of the Alltrax's field
> connections went nowhere?  
> I think I recall that Alltrax controllers also don't
> like open field 
> connections so that could cause it some
> consternation too.
> 
> 
> David Roden - Akron, Ohio, USA
> 
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