Improvements in Regulating Polyphase Oirouits.
Year: 1896

page_text: Date of Application, 17th Nov., 1896-Accepted, 1st May, 1897
COMPLETE SPECIFICATION.
Improvements in Regulating Polyphase Oirouits.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon
Street, in the City of London, Electrical Engineers, do hereby declare the
Dature of this invention (which has been communicated to us from abroad by
Albert H. Armstrong, of Schenectady, in the County of Schenectady, State of
New York, United States of America,) and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
*:
Our invention relates to the regulation of polyphase alternating current circuits,
and particularly to the regulation of induction motors, in which latter case it finds
its greatest utility; and bns for its object to provide an improved regulator in
which the output of such motors is controlled by variation of position of the moving
and stationary parts of the regulator, as more fully described hereafter, the electric
actions depending upon variation of phase relation between. the electro-motive
forces in the coils of the induced member and the line respectively.
In its broadest aspect, our inventiou comprises both a method of and means for
regulating an alternating current motor, translating device or circuit of any desired
type. In this view it consists in combining with the main electro-motive force
derived from the generating source another constant electro-motive force, and then
varying the phase relation between the main impressed electro-motive force and tho
constant electro-motive force from coincidence of phase to direct opposition;
the resultant electro-motive force (which may be anything desired, depending upon,
the relation in magnitude between the impressed and regulating electro-motive
forces), is utilized in the motor, translating device or other circuit which is to be
regulated.
To the ends pointed out, we construct our improved regulator with two windings,
a polyphase inducing and induced winding, the inducing winding being in shunt to
the mains, while the induced windings are in series with the work. The voltage
of the induced member thus remains substantially constant; but by varying its.
position with reference to the inducing coils, we change the phase relation
between the electro-motive force induced in this member and that in the line.
from coincidence to opposition, so that the full voltage induced may be either,
used to assist the line voltage, and thus to raise the electro-motive forco
impressed upon the motore, or it may act as a counter electro-motive force and
cut down the voltage at the motor terminals, thus regulating their torque, which is
proportioned to the square of the impressed electro-motive force.
A convenient form in which we have embodied our invention resembles an
ordinary induction motor, the field being in shunt between the lines and tlie
armature being in series in the lines, a suitable controlling handle being provided
by which the position of the armature may be adjusted to the work required.
Any convevient way of maintaining the armature and field (using the terms in their
ordinary sense) in the adjusted position, may be selected.
.
The accompanying drawings show an embodiment of our invention,
Figs. 1 and 2 being a side and end elevation respectively of its mechanical,
tructure,
Fig. 3 diagram of the windings in a three-phase apparatus of the type.
:

page_text: Fig. 4 is a diagrammatic illustration showing an electric railway system with
one of our improved regulators in circuit with the motor, and
Fig. 5 a diagram of an electric car equipped with my improved regulator.
In Figs. 1 and 2, A is the base of the regulator, B the inducing member, or
field, as it is commonly called, and C is the induced or regulating member or
armature; D is a handle attached to the regulator, working over a sector E.
No collecting rings or similar devices are illustrated (though they might be
employed), inasmuch as the connections to the moving member may be readily
made by flexible leads, shown at N in Fig. 2.
In Fig. 3 the diagrams of the windings will be readily understood from
inspection. A three-phase winding is illustrated, the heavy black line 1
representing one set of coils, tho dotted line 2 a second set, and the broken
line 3 a third set, all of those being united by a common connection 7, and
being situated upon the inducing member. The connections are not illustrated in
this figure, but these coils aro connected in shunt between the different lines,
the whole apparatus being shown as of the three-phase type. The windings of
the inner member are of the same type as those upon the armature of an
induction motor, the sets of coils being respectively represented by the solid line 4,
the broken line 5, and the dotted line 6. In this case also the connections are not
illustrated, but each of the sets of coils is supposed to be in series in one of the
mains of the system.
In Fig. 8 1 have shown a four-pole three-phase regulator with the primary or
inducing member outside of the secondary or induced member. The inducing
member or primary is Y-connected and is in shunt to the supply mains.
Considering coil 1 of the inducing member and coil 4 of the induced member,
shown in heavy black liuer, the flux set up by coil i represents a portion of the
total flux enclosed within its area; besides the flux set up by coil i, there is the
resultant flux of coils 2 and 3 added to it. The sum of these fluxes will be
substantially constant in all portions of the field, so that the induced member will
have a constant potential in all positions. In the position shown the flux traversing
primary coil 1 will also pass through the area enclosed by secondary coil 4, and the
electro-motive forces of the two coils will be proportional to the number of turns
in each.
Coil 4 is connected in series with one of the supply mains which is shunted by
coil 1, so that its electro-motive force is either added to or subtracted from that
of coil 1, and thus added to or subtracted from the electro-motive force of the
source of supply, according to the relative angular position of the coil. By moving
the induced member through an angle of 180°, the flux set up by the inducing
member will pass through the coils of the induced member in the opposite direction,
su that the electro-motive force of the induced member will be reversed, and
whereas the electro-motive force of coil 4 was added to the electro-motive force of
coil 1 in the first case, it will now cut down that voltage in the same ratio. If
coil 4 is moved from the position shown in Fig. 3 through an angle of 90°, its
electro-motive force will be the same direction, but will be produced by a flux
which is displaced from the flux of coil 1 by an angle of 90, so that when the
electro-motive force of coil 1 is at a maximum, the electro-motive force of coil 4
will be at a minimum or zero, and will have no offect upon coil 1 if the latter
is connected in series with one of the maius energizing coil 1. It is evident that
any intermediate angular displacement of coil 4 from coil 1 causing its electro-
motive force to be displaced a greater or less angular amount with respect to the
electro-motive force of coil 1, will result in a greater raising or lowering of the
supply voltage.
In Fig. 4, G is a generator of three-phase currents sent out over the lines a, b, c,
representing a railway distribution. The regulator K is carried upon the car, and
trolleys T are connected with the lines. The coils 4, 5, 6, are respectively connected
in series with the work, represented by the motor M, the coil 4 being in series with
the coil n upon the motor, the coil 5 with the coil p, and the coil 6 with the coil o.

page_text: It is of course intended that these three coils shall be arranged, as in Figs. 1 and 2,
upon a rotatable structure by which their position with reference to the coils 1, 2, 3,
of the inducing member or field may be varied. These latter coils are connected
in Y, and are in shunt to the mains.
In Fig. 5 wo illustrate diagrammatically an electric car L connected by the
trolleys. T to the mains, provided with controllers K K of the general type just
described, and a three-phase motor M. With the controller which we have just
described may be combined any suitable circuit-breaking arrangement for cutting
off the power from the motor, or any proper emergency switches or other devices
of that class; this forming no part of our prosent invention, may be varied in any
desired way without departing therefrom.
Our present understanding of the operation of the devices just described is that
the phase relation of the electro-motive force induced in the series coils with
reference to that in the mains is determined by the position of these coils with
reference to the coils in shunt to the mains, and may be varied by changing the
relative position of the induced and inducing coils, from coincidence, assisting the
electro-motive force of the mains, to 180° difference in phase, opposing this electro-
motive force. Assuming that five hundred volts difference of potential existed
between the lines, and, say, one hundred and fifty could be generated in the series
coils; the electro-motive force impressed upon the motor might be varied between
350 and 650 volts, with proportionate change in its torque. In the arrangement of
our invention the voltage in the induced member remains constant, and the phase
relation is the only thing that is changed; whereas in other regulators with which
we are acquainted, the voltage in the induced member is varied from a maximum in
one direction through zero to a maximum in the opposite sense. In other cases the
effect has been obtained by varying the flux passing through the induced coil, and
it is therefore necessary to provide at the zero position a short-circuited coil cutting
down the self induction of the induced winding, as in this position, though doing
no work, it carries full line ourrent. In the present case, however, the flux is
constant, and no such coil is necessary, the voltage remaining constant, the only
drop in the induced member being that due to its inductance.
Having now particularly described and ascertained the nature of this invention
(as communicated to us from abroad) and in what manner the same is to be performed,
we declare that what we claim is :
1. The art of regulating a polyphase alternating-current motor, translating devico,
or other circuit, which consists in introducing between the circuit to be controlled
and the main source of polyphase electro-motive forces intermediate constant
electro-motive forces and varying the phase relation between the electro-motive
forces of the lines and those of the intermediate source from coincidence to opposi-
tion, thus impressing upon the motor or other device to be regulated the desired
resultant electro-motive forces.
2. An alternating current regulator comprising a polyphase inducing member
having interconnected coils or windings in shunt between the mains of the distri-
buting system, an induced member having a core and an independent coil or winding
in series between each supply line and the work, and means for varying the relative
angular position of the inducing and induced windings so as to vary the phase
relation between the electro-motive force of the line and that in the induced member
of the regulator.
3. An alternating current regulator, comprising a fixed inducing member and a
rotatably mounted induced member, the first having a winding in shunt to the lines,
and the second a core and winding comprising an independent coil in series between
each of the supply lines and the work, and a handle for changing the relative
angular position of the rotating and fixed members, and thereby the phase relation
between electro-motive forces in the coils carried upon them.
4. The combination of a genorator of alternating current, and lines leading
therefrom between which a desired difference of potential is maintained, with a

page_text: regulator comprising a polypbase inducing member having coils interconnected
in hunt between the lines, and an induced member having a core and an inde-
pendent coil or winding in series between each supply line and the work, and
means for varying the relative positions of the two members so as to change the
pbase relation between the lino electro-motive force and the electro-motive force of
the induced member, and thus regulate the electro-motive force impressed upon the
working circuit.
5. In combination, a generator of alternating current, lines leading therefrom
and supplying an electric railway, a travelling vehicle upon the railway deriving
its energy from the lines, a polyphase alternating current motor or motors on the
vehicle, and a regulator also carried upon the vehicle, and comprising a polyphase
inducing and induced member, the former connected in shunt between the lines,
the latter having a core and an independent coil connected in series between each
supply line and the work and means for varying the relative position of the
windings carried by the two members, and thus impressing upon the motor or
motors a resultant electro-motive force depending upon the phase relation
between the line electro-motive force and that in the induced member of the
regulator.