[PRCo] Re: Interurban PCCs ???

[John Swindler]

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
>
>