In article <%Oa4k.58119$bs3.21880@[EMAIL PROTECTED]
>,
Pac Man <cutler2@[EMAIL PROTECTED]
> wrote:
>Ian Jackson <ijackson@[EMAIL PROTECTED]
> wrote in message
>news:9dF*Opefs@[EMAIL PROTECTED]
>> What an astoni****ng design. Well, err, forget most of the rest of
>> what I said. I had assumed that these things were actually controlled
>> somehow rather than just waiting for the short and then flipping.
>
> That's the way all auto-reversers work.
So I now discover. I didn't have the dubious benefit of knowing this
when I designed my own arrangements so I have a system where the
polarity is set correctly before the train arrives. (Well, I probably
wouldn't have done it differently anyway ...)
>> I did a bit of websearching and it suggests that they're adjustable.
>> That is, the current at which they flip is adjustable. Have you tried
>> increasing it ? This will (as the sites I saw agreed) increase the
>> energy in of the sparks and thus the damage to the wheels each time
>> they operate but such damage is inevitable with the design.
>
> Damage? Nope. I've been running auto-reversers on my club's layout
for
>7 or 8 years, using an MRC, a Digitrax' PM42, and a Digitrax Booster set
up
>for it. I've never seen sparks at the electrical isolation gap of an
>auto-reversing section in use. The reversers are so sensitive & quick
that
>they trip without sparks. Honest.
OK, I believe you. Versions which use solid state relays rather than
electromechanical relays should certainly be able to limit the energy
released to reasonable levels. My own layout has of course a
short-circuit cutout which is sensitive enough to prevent any damage
so it must be possible.
The OP however was using relay-based reversers which will be much
slower. Also, I imagine the relays' contact lifetime is not ideal
due to arcing when opening carrying a fault load. I wonder if they
manufacturers have done tests to determine whether the relays still
have an acceptable service life.
--
Ian Jackson personal email:
<ijackson@[EMAIL PROTECTED]
>
These opinions are my own.
http://www.chiark.greenend.org.uk/~ijackson/
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