(ET) e-15 eats reverse relays

["Pieter Litchfield" <plitch attglobal net>]

To again follow up on this item (for the sake of our collective knowledge):

I consulted with Bill about the relay eating E-15, and he gave me some
mechanical checks to perform - these are listed below.  I also bought two
(one for a spare) reversing relays, "new" style and replaced the burned one
(also a "New" Gunn style).  I determined that the big blue bolt of 
lightning
is only produced when shifting from reverse to foward with the motor still
coasting, but that all the switches controlling the current seem to be
sequencing correctly.  In addition, the VDR-1 circuit showed no
discoloration or physical damage.

So I guess this means I will have to remember to be sure to wait for the
motor to stop completely before changing direction.  I have tested the 
trac,
and it is working just fine.  Memory don't fail me know......

-----Original Message-----
From: owner-elec-trak cosmos phy tufts edu
[mailto:owner-elec-trak cosmos phy tufts edu]On Behalf Of Pieter
Litchfield
Sent: Tuesday, June 11, 2002 4:14 PM
To: Discussion list Electrac tractor
Subject: RE: (ET) e-15 eats reverse relays


Just to bring you all up to date:  I did talk with Bill Gunn today.  He 
gave
me some mechanical checks to perform (5!!) .  These involve checking to see
if VDR-1 is dead (likely to be obvious discoloration, cracks,etc), see if
involved circuits have tight connections, and see if the speed control 
lever
has faults- reverse reply not kicking in/out soon enuff and power engaged
before reverse relay engaged.  So I have some mechanical things to check
out, and it will be a few days before I can get to it.  However, I will let
you all know the outcome, if any, so we can all "grow" by my experience.
This is not an uncommon problem.

By the way, Bill said to be sure in ANY CASE that I wait for the motor to
come to a full stop before reversing.  All of us should listen to these
words of wisdom.

Pieter


-----Original Message-----
From: owner-elec-trak cosmos phy tufts edu
[mailto:owner-elec-trak cosmos phy tufts edu]On Behalf Of Elie, Larry
(L.D.)
Sent: Monday, June 10, 2002 10:34 AM
To: Discussion list Electrac tractor; Tom G
Subject: RE: (ET) e-15 eats reverse relays


In layman's terms; I think the circuit is ringing.  I work with large
inductive loads.  Try to turn them off to quickly and there isn't anywhere
to dump the current; the contacts, or controls down-wind of them may fry.
An active device (Varistor) may help, or even a passive (Resistor) may
absorb them IF you know how much energy is involved.  I'm surprised GE
didn't take care of this.  I'm about to rebuild an E-15 and will look into
it.

Larry Elie