Re: What's that noise?

[Gareth Lumsden <s9763278@minyos.its.rmit.edu.au>]

On Wed, 28 Apr 1999, Ron BEST wrote:

> It's the same with trams. When accelerating, a high current is drawn from
> the overhead. If, for some reason, the driver "notches back", this current
> has to be interrupted. The sound you hear and the arc is a result of  the
> line-breaker (a large circuit-breaker) opening under heavy current. (BTW,
> one of the tram noises I love to hear is that one - in a W tram.)

Thanks!

So basically it is the simple theory of electrons flowing, then 'jumping'
across the line-breaker when it is opening.  Much the same thing when a
tram is powering over a cut off point - A large arc 'jumping' between the
contact wire and the overhead.  Comeng trains just make a louder noise
because there is more voltage.  Have I got it right?

Thanks again,

Gareth.

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