[PRCo] Re: Interurban PCCs ???

[Boris Cefer]

Also in PTM files I found a hand written note on something (possibly in a WH
instruction book) and it simply stated that PRCo 16s and 17s had higher
balancing speed. But there wasn't any particular figure.

Further discussion of the motor engineering in our PRCo subgroup :-D

B

----- Original Message -----
From: "John Swindler" <j_swindler at hotmail.com>
To: <pittsburgh-railways at dementia.org>
Sent: Monday, March 28, 2005 4:30 AM
Subject: [PRCo] Re: Interurban PCCs ???


>
> electrical mechanical force.
>
> Actually, Boris, you provided a much clearer explanation.  Thanks.
>
> For some reason, 47 mph sounds vaguely familiar.  But I have no
recollection
> where I heard/read that.  Sorry.  (HELP!!)
>
> John
>
>
>
>
> >From: "Boris Cefer" <westinghouse at iol.cz>
> >Reply-To: pittsburgh-railways at dementia.org
> >To: <pittsburgh-railways at dementia.org>
> >Subject: [PRCo] Re: Interurban PCCs ???
> >Date: Sun, 27 Mar 2005 20:24:09 +0200
> >
> >Yes, the balancing speed (assumed on dead level) of an average PCC car
with
> >full field excitation is roughly 30 mph. With the exciting field weakened
> >by
> >the field shunts the speed at which all mechanical resistances equal the
> >tractive effort is higher, roughly 42 mph. That's correct for roughly 50
%
> >field shunting. With higher field shunting (67 % on those 16s and 17s
with
> >WH equipment) the balancing speed on dead level would be higher, but I
can
> >only speculate how much. When the high field shunting is applied, the
rate
> >of acceleration at higher speeds (with the accelerator resistance
> >shortcircuited) is slightly higher, which was possibly the main intent of
> >that improvement. Possibly the high shunting allowed the cars to gain
> >speeds
> >in slight excess of 50 mph and therefore the overspeed relays were
included
> >in the schematics to avoid motor damage (maximum safe motor speed is just
> >50
> >mph).
> >
> >Am I missing anything by the EMF? Ah, the language! :-)
> >
> >Boris
> >
> >----- Original Message -----
> >From: "John Swindler" <j_swindler at hotmail.com>
> >To: <pittsburgh-railways at dementia.org>
> >Sent: Sunday, March 27, 2005 7:46 PM
> >Subject: [PRCo] Re: Interurban PCCs ???
> >
> >
> > > Does that mean, Boris, that the balancing speed of a PCC motor would
be
> > > around 30 mph on level track with 600 volts.  And it is the weakening
of
> >the
> > > field that allows the motor speed to increase to propel a PCC car to
> >around
> > > 42 mph??  In other words, at what track speed would the back EMF equal
> > > applied force without field shunting??  And with field shunting???
> > >
> > > John
> >
> >
>
>
>