Re: Dead hauling QR diesels

[David Johnson <trainman@ozemail.com.au>]

Aus loco discussion mailing list

Trevor Gibbs wrote:

> Aus loco discussion mailing list
>
> Hello there
>
> There are I guess pros and cons to having a loco idle while being
> towed, but the concept of being bad for Traction motors should not be
> one of them. THe only consideration would be any voltage that could be
> generated while the loco is being moved having "nowhere to go" because
> it is
> disconnected through what are known as recirculating currents. This
> would be minimal as a loco to get any real form of excitation for
> Dynamic Braking had to be placed in the equivalent of Notch 4 speed to
> work. LatMore modern locos can excite their traction motors as a fuel
> conservation measure at a much lower rev rate so there might be a
> slight problem there.

There would be no field excitation, therefore, no armature current production.
Even if there was some residual magnetism causing small amounts of EMF from the
armature, the open line switches would ensure that it does absolutely nothing.


--
David Johnson
trainman@ozemail.com.au
http://www.ozemail.com.au/~trainman/
------------------------------------
These comments are made in a private
capacity and do not represent the
official view of State Rail.
C.O.W.S. Page 11.


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