[GreenKeys] Re: W.U. Motor Control Relay

[Bob Camp]

Hi

A lot of the stuff we now have went through a number of generations  
of "driving side" gear. The cost of wire lines was a significant  
thing. With a polar circuit you can't put a whole lot of different  
machines on the same line.

Once local loop tone based multiplex systems became practical, there  
was a significant reason to convert over to them. The tone multiplex  
boxes were basically what we would call a TU and it was cheaper to  
build them without the polar features. The machines all went off to  
conversion land to get the polar stuff disabled ....

Bob


On Jun 9, 2007, at 10:51 PM, jhhaynes at earthlink.net wrote:

> The one pictured on the back of a Model 15 is a Model 15 motor control
> relay, and that was going to be the subject of another question later.
>
> The one I'm talking about in W.U. machines must be polar, is connected
> in series with the line, and contacts in series with the motor.  On
> some old W.U. machines in the post office cabinets the relay is in  
> a box
> inside the cabinet that also has a couple of jacks and resistors and
> things.  But every one I have ever seen has the relay removed, so I've
> never seen the relay.  It is some kind of quick-change thing, that
> mounts to a fixture having four contacts, two for the line and two for
> the motor circuit.
>
> Now getting on to the Model 15 motor control relay, mounted on the
> Model 15 base.  I think nearly all Model 15 bases have wire loops
> for this relay and many of them have the relay too, but often not
> connected.  And the Model 15 manual is not very clear on how that
> works either.  Says something about polarity reversal for motor  
> control,
> but the relay isn't a polar relay.  So I'm not clear if it is operated
> by contacts on the line relay, or some other way.
>
>
>
>
> jhhaynes at earthlink dot net
>
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