Improvements in and relating to Regulating Electric Motors in Three Wire Systems of Electric Railways.
Year: 1895

page_text: Date of Application, 22nd Oct., 1895-Accepted, 15th Feb., 1896
Improvements in and relating to Regulating Electric Motors in
Three Wire Systems of Electric Railways.
I, JAMES DEVONSHIRE, Secretary of the Buitish Thomson Houston Limited
of 38 Parlament Sticet, Westminster, London do hereby declare the nature of
this invention (a communication from abiond by Wilham B Potter, Electrical
Engineer, of Schenectady, in the State of New York, United States of America)
and in what manner the same is to be performed to be particularly descubed and
ascertained in and by the following statement:-
My invention relates to the regulation of electric motors such as are used in
electric railway work. It particularly refers to an adaptation of the well known
series multiple or three-wire system to clectic railways; and has for its object
to employ in such a system in practice a voltage of 1000 or 1200 between the
positive and negative mains, so combining and operating the apparatus that I may
with this voltage employ standard railway apparatus, which, as is well known, is
designed only to stand a maximum voltage of 500 or thereabouts.
To accomplish the ends pointed out, I employ two motors upon one side of the
system, and two other motors upon the other side, each of the motors being
adapted, as already descubed, for 500 volts potential, and the connections of the
wing are those commonly adopted for railway work, that is to say, employ
two generators in series and ground the connection between them, using the earth
and the rails as a return circuit, or more strictly, as the neutial of the three-wire
system; but, by the airangement which I have adopted, 1 do not at any time
return the main current through the earth or track rails, the path of the current
being first through the two motore to a common ground connection from the main
having 500 volts positive potential, and then returning by the other line at 500
negative potential; only where one pair of the motors would be slightly out of
It is
balance with the other pair would any cutient at all flow in the neutral
manifest by this arrangement that I may, if so desued, either dispense altogether
with bonding the rails, or I may connect them with light wires, and thus save a
very heavy expense in the copper cost of the road. It is of course to be under-
stood, that with this arrangement of wiring I employ the series parallel method of
control for the two sets of motors, such, for instance, as that referred to in
British Patent granted jointly to myself and W. II. Kuight July 30th 1892,
No. 13920
By the system thus fai described, each car maintains a perfect balance within
itself. Ordinarily I employ two controllers of standard construction, they may
be placed adjacent to each other and geared to work together from a single
operating handle. This, however, I do not consider indispensable, though
preferable.
The arrangement as thus far described, necessitates the use of double trolleys, and
this is contemplated in the present invention; this arrangement is particularly
adapted for long distance or tiunk-line work. Where, however, such lines connect
with lines within the city limits upon which lower speed is desued, I provide
therefor as follows. I so aange the apparatus that at a certain point outside the
city one of the trolleys is withdrawn and the motors are operated, all four in
series, between one of the trolley lines and ground in the usual manner. For this
purpose I provide a switch which changes the arrangement at the time of drawing
down the trolley, so that as ordinarily run in the three-we or double trolley

page_text: parts of the line the combinations of the motors will be, two sets of two in selles,
aud then two sets of two in multiple, with the usual resistance control incorporated,
but when the second trolley is drawn down and the switch thrown the combination
would be all four motors in series, thus giving great efficiency over the parts of
the road whicie ordinarily the speed is lowest, and where in other systems the
efficiency is also lowest because of the large amount of resistance necessary to
bring the speed to that proper for transportation through the sticets.
Where other loads are crossed, I arrange the working conductors in any
convenient manner so that they will have approximately the same voltage, aud of
the same sign, and thus avoid the risk of impauing the insulation or leakage of
curient
By the arrangements thus far pointed out I am euabled to effect a very great
saving in copper, at the same time securing a uniformity of operation in the 1oad
which is impossible with a road using the track as its main return, because the
resistance of the track varies so between wet and dry weather as to make a great
difference in the operation of the cars I also prefer to connert portions of the
working single conductors in alter nation to the positive and negative sides of the
system For instance, I would connect, say a mile of one conductor to ono side
of the system and by the insertion of trolley breakers, so-called, such as herem-
after explained, being short lengths of insulated conductor over which the trolley
passes operatively, I would connect the next mile to the other side of the
Eystein.
By this method the grades will be divided in such a way that the two
sides of the system would not become unequally loaded, if for any reason it should
become necessary (as by the burning out of both motors upon one side) to in the
long distance trains upon one side of the system ouly.
The accompanying drawings show diagrammatic representations of my invention.
In these diawings,
Fig 1 is a diagram of a portion of the road equipped for both a three wire
system and the city system, showing, a cai upou each part:
Fig 2 is a diagram showing the motor connections of the cars when running as
shown in Fig. 1 -
Fig. 3 is a top plan view of two controllers geared to operate from a single
handle
Figs. and 5 are diagrams showing the motor connections when in upon the
double trolley of three-wne system.
In Fig. 1, A B are the generators having a common ground connection, G, to
the track, sei ving, as illustrated, for the neutral main of the three-wie system:
DD are the positive mains or conductors: EE are the negatives.
It is to be understood that the positive condictors are at 500 potential plus,
while the negatives are at 500 potential minus, the ground being taken as zero.
The feeders are also shown, marked D' E' respectively. The leads from the
generators are marked FR respectively, and connect in a proper way with the
positive and negative working conductor." I have not illustrated in full the system
of feeders proper to be employed, as that would be well understood by those
versed in the ait. 00' are cars running respectively upon the three-wire and
the two-wne parts of the system. The connections for the part is that shown
upon the left in Fig. 2, while that of the car O' is that shown upon the night in
the same figure. The cars are provided with controllers K and with trolleys I I
A switch 16 also provided in the cucuit of the trolley 1' which runs upon the
negative conductor. This switch may be arranged to be operated by the pulling
down of the trolley, in which case the trolley would be provided with some form of
automatic detent, or it may be a hand-operated switch, and still be within the
scope of my invention. The path of the curent, as illustrated in Fig. 2 on the
left, would be, from the trolley 1, through one of the controllers, through
the motors 4 and 3, to ground; fiom ground through the notors 2 and 1 to the
Switch S, trolley I¹ and back to the generator, the ground G taking only, the
amount of current necessary to keep the system in balance.

page_text: In this arrangement it is manifest that 1,000 volts potential may be used, and as
the ground connection G is left in at all times when running upon the three-wire
system, the apparatus would only be subjected to a potential of 500 volts.
I also embody in my invention a peculiar disposition of the positive and negative
conductors by which I am enabled to effect a rapid transfer of the vehicle at those
points in the system where I change from three-wire to the two-wire arrangement.
This also is illustrated in Fig Therein it will be observed that the upper
working conductor E is of negative potential, while its corresponding conductor D
18 positive In the lower part of the figure, however, the working conductor D 18
positive and the conesponding conductor E is negative. This presents the
advantage of making the adjacent conducts, or rather, the conductors on adjacent
tracks, of the same sign and potential so that they may be, if desired, inter-
connected readily to assist in the equal distribution of current
In the upper
conductor E the first trolley breaker II divides the line in such way that the
succeeding section, or the section between the two trolley breakers HH, is positive,
and as will be observed, it is fed from the positive feeder D'
The portion,
however, beyond the second trolley breaker II and the lower trolley breaker H' 18
of negative potential. I so aange the conductors that one of them, the one which
is to be used when the two-wire system is employed, 19 suspended over the middle
of the track, and the other conductor is suspended at a short distance to one side,
sufficient to preserve the proper insulation It 13, of course, to be understood that
the trolleys are suitably aanged, one of the trolleys being displaced with reference
to the other and the centre of the cal.
Upon the right in Fig 2 the trolley 1', as upon the night in Fig. 1 in case of
the car O, is depressed The switch S is also thrown and the central ground
connection G is broken and the other ground connection G'substituted therefor,
so that in this position the path of the current would be from the trolley I though
one of the controllers, through the motors 4, 3, 2, 1, over the switch S and out to
ground at G. Of course, in this instance the entire voltage available would be
only 500.
In Fig. 3I have illustrated two controllers of the type already referred to, placed
back to back so as to practically form a single controller. A common operating
handle is provided with a single gear L"meshing into the two pinions L L upon
each of the controller cylinders respectively Two reversing switches N N are
also provided, and these are also connected by a rod N³, so that when one is thrown
the other is also operated With the exception of the gearing the parts are well
known in the art,
Referring to Figs. 4 and 5, I show in diagram the combinations employed in
unning the apparatus on the three-wire system, it being understood that in every
case the intermediate connection between the motors is grounded.
In Fig. 4 the path of the current is from plus trolley line through the motors 43
to ground, and from ground through the motors 21 to the minus line In Fig. 5
the path of the current will be from the plus trolley line through the motors 4 and 3
u multiple to ground, and similarly from the ground through the motors 21 in
multiple to the minus line.
By the system which I have just pointed out I not only obtain great flexibility
of control and avoid the necessity of bonding the rails heretofore existing, but I
am enabled, while using 1,000 or 1,200 potential, to employ standard apparatus
operating upon half that potential, and to thus effect very great saving in the
copper cost of the road. At the same time I avoid all trouble in balancing the
ystem and from improper operation of the motors caused by this, and caused by
the motors robbing each other of current It has been proposed to employ in long
distance transportation, such as that to which my system is particularly adapted,
wo generators in series and to always employ two motors in series, but it
s manifest that this is an impracticable arrangement, inasmuch as if one of
be motors alips they might be both destroyed before the slip is overcome,
r if one of the motors becomes disabled from any cause the other motor

page_text: could not be used to operate the train, but the ente equipment would
be disabled, whereas by the plan which I have adopted it is perfectly feasible to
cut out one motor upon each side of the system and operate the train from the
emaining motors, as they in this case are substantially in series on 1,000 volt
encuits with the ground connection, ho vever, still in, so that each moroi is only
subjected to five hundred volts difference of potential This may be, in case of
two motors, the method of running the system; that is, instead of the fout motors
which have illustrated, employ in some cases two motors only. In this
application, however, I do not specifically claim these two motors, although in the
claims which I make I aim to embrace this combination in the broadest aspect of
this case
It is also feasible at any time to disconnect one side of the system and
operate the equipment upon the other side alone, where this becomes necessary
for purposes of repair or from accident, the motors then running in parallel upon
500 volts, the system which I have devised thus becomes of great flexibility and
better adapted for the purposes designed than any with which I am familiar.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me
fiom abroad I declare that what I claim is
The art of operating electric motors upon a three-wire or series-multiple
electie railway, which consists in 1unning upon each cat an equal number of motors
upon each side of the system, and sunultaneously making similar changes or steps
in the control of each set of motors.
2. The art of operating electric motors upon a three-wire ou series-multiple
electric railway, which consists in dividing the motors upon each cat into two
groups, one group upon each side of the system, aud simultaneously operating the
two groups by the series-parallel system of control.
3 The art of operating electric motors driving an electrically propelled vehicle
herein set out, which consists in connecting the motors in groups of two upon
opposite sides of the three-wie system for one rate of speed, and then connecting
them in a single group between the ncutral and one of the opposite wires of the
system for different speeds
4. An electrically-propelled vehicle, a plurality of motors thereon connected in
groups or sets upon the two sides of a thiet-wite system, and reans controlled by
a single handle for simultaneously regulating the two sets of motors
5. In combination, a railway tiack forming the neutral in a three-wire system,
positive and negative conductors forming the outer wires of the system extending
along the track, an electrically-propelled vehicle on the track making traveling
contact with both the positive and negative conductors, motors upon the vehicle in
cucuit with each side of the system, and means cared by the vehicle for
simultaneously regulating the motors upon each side.
6 An electrically-propelled vehicle, a plurality of motors thereon divided into
two groups, one group connected upon each side of the three-wie system, a
controller for each group and a connection between the controllers whereby they
are both operated by a single handle, and the motors simultaneously regulated upon
each side of the system
7 An electrically-propelled vehicle, a plurality of motors diving the vehicle, the
motors being connected in groups upon each side of a series-multiple or three-wire
system, and means for regulating the motors
8. A plurality of electic motors connected in groups upon each side of a three-
wire on selles-multiple system and simultaneously diving to a common load, and
means for regulating the motors
9. A plurality of electric motors connected in groups upon the two sides of a
three-wire or series-multiple system and geared to a common load, and means for
controlling the motors in each group by the series-parallel system of control.
10. An electrically-propelled vehicle, a plurality of motois thereon divided into
groups on sets of two connected upon each side of a series-parallel or three-wire

page_text: system, and controlling means for the motors aanged to simultaneously control
the motors on each side by the series-parallel system of control, substantially as
described.
11. In a three-wire system of electic always the combination of a pan of
motors, a controlling switch for such motois, a second pair of motors, a similai
controlling switch for the second pair of motors, and common operating means for
the two controlling switches.
12. In a three-wire system of electic railways the combination of a pair of
motois, a series-parallel controlling switch for the two motors, a second series-
parallel switch for the second pair of motors, and means for simultaneously operating
the two controlling switches.
13. In a series-multiple or thee-wire electric railway having two tracks or sets
of conductors, adjacent conductors for the different tracks having the same sign
and potential, substantially as and for the purpose described.
Dated this 22nd day of October 1895.
J. C. CHAPMAN,
70, Chancery Lane, London, W.C., Chartered Patent Agent.