Improvements in Systems of Distribution by Alternating Currents.
Year: 1895

page_text: Date of Application, 9th Feb., 1895-Accepted, 18th May, 1895
COMPLETE SPECIFICATION.
Improvements in Systems of Distribution by Alternating Currents.
I, JAMES DEVONSHIRE Secretary of the British Thomson-Houston Limited,
of 38 Parliament Street, Westminster, in the County of Middlesex, (a communication
to me from abroad by Charles P. Steinmetz, of Schenectady, County of Schenectady,
State of New York, United States of America,) do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
The present invention comprises what I term a monocyclic system of distribution,
and consists of certain improvements whereby lamps or other single-phase
translating devices, as well as multiphase motors, may be supplied with current
from a single source of power and a common system of circuits. The system
resembles in some respects the ordinary alternating single-phase distribution
systems such as are now used extensively for lighting purposes, but by the present
invention such a system is rendered capable of operating multiphase motors as
well as lamps when desired without the necessity of installing special multiphase
generators for the motors or running special circuits. In fact, by the present
invention the generators employed may be installed for an ordinary lighting
system, and whenever it is desired to operate motors as well as lamps it is only
necessary to run an additional main to the point or points where the motors are
located and to maintain upon this main an out-of-phase electromotive force, so
that between this main and the single phase mains polyphase electromotive forces
will exist. This end is attained through the agency of a supplementary or phase-
modifying source of electromotive force so arranged as to act jointly with the
main source of electromotive force but having a different phase relation, so that
by the combined action of the main and supplementary sources an electromotive
force of displaced phase is maintained upon the third or intermediate main of the
polyphase circuit.
There is a wide variety of ways in which this combination of electromotive
forces may be secured in practice. The general method herein set out consists in
the use of a phase-modifying coil on the main generator which is of the ordinary
single phase type, this supplementary coil having a displaced position from the
main winding in the field of force so as to tend to generate an electromotive force
of different phase from that generated in the main winding. This coil is connected
at one end to an intermediate point in the main winding and at the other end to
the intermediate main of a polyphase circuit, the outside mains of the circuit
being connected to the terminals of the main winding. By this arrangement an
alternating electromotive force is maintained between the two outside mains by
the main winding of the generator while resultant electromotive forces are
maintained between the intermediate main and the outside mains respectively,
which are due to the joint action of the main winding and phase-modifying coil
and which are out of phase with one another and with the electromotive force
existing between the outside mains.
In the accompanying drawing illustrating the invention,
Figure 1 shows a distribution system in diagram; Figure 2 shows in a similar
manner a distribution system comprising a bank of dynamos in which monocyclic
machines are working in multiple with ordinary single-phase machines ;
Figure 3 is a diagram sbowing means of regulating the phase-modifying coil of
this generator

page_text: Figure 4 is a geometrical diagram illustrating the relation between displacemen
of phase and the relative values of the component electro-motive forces.
In Figure 1 the generator comprises an armature winding A A², whose terminals
are connected to collector rings R R² and which is arranged in a manner similar
to ordinary single-phase alternating dynamos. The winding A A² constitutes the
main source of electromotive force and maintains alternating electromotive force
waves in the mains ac connected respectively to the collector rings which constitute
either a single-phase circuit or the outside mains of a polyphase circuit. The
field of the generator is wound with a coil F in circuit with a separate shunt wound
exciting dynamo E, and a resistance I is provided for regulating the exciter.
For compounding or over-compounding the main dynamo, its field may also be
provided with a series coil F', the current in which is rectified by a commutator K,
and a resistance is shown shunting the commutator brushes to prevent sparking,
though this forms no part of the invention. The intermediate main b of the
multiphase circuit is connected to a third collector ring R³, and the phase-
modifying coil A' which occupies a displaced position in the field of force has one
terminal connected to this collector ring and its other terminal to a point at or
near the electrical centre of the main winding as shown in the diagram. When
single-phase translating devices alone are used the phase-modifying coil will be
open circuited, and at such times the system will operate in all respects as any
ordinary alternating system, the single-phase translating devices, such as lamps,
being connected electrically or inductively with the outside mains a c, and the
intermediate main being dead. When polyphase currents are desired the phase-
modifying coil is connected to the intermediate main, and electromotive forces are
then maintained between this main and the mains a e respectively, due to the
resultant action of the coil A¹ and the halves of the main winding A A2, which
are out of phase with one another and with that maintained by the unmodified
action of the main winding between the mains a c. When now translating devices
are connected with the three mains, polyphase currents are obtainable having a
phase relation determined by the resultant action of the main and supplementary
sources of electromotive force.
Two
In the diagram, Figure 1, a circuit of lamps, which require only single-phase
currents, is shown connected inductively through the transformer T with the
mains a c.
At the right of the figure a system of transformers is shown, suitable
for transforming multiphase currents derived from the three mains.
transformers, T5 and T6, are used whose primaries are connected in series and
whose free terminals are connected to the mains a c, while the intermediate main b
is connected to a point between the primaries. The secondaries are similarly
connected. Such an arrangement will transform the primary currents into
secondary currents of different potential, but having the same phase relation.
In Figure 2 a bank of generators is shown connected to common bus bars B, B1, B².
Two of these generators G G¹ are of the monocyclic type already described,
provided with phase-modifying coils A' connected to an intermediate point in the
main coil A, A2, and to the bus bar B¹. The remaining generator G2 is of the
ordinary single phase type with its terminals connected to the bus bars B, B.
The field coils of the different generators are all excited from a separate direct
current machine E and may be independently regulated by rheostats I, I, I. The
arrangement of distributing mains a b c, of transformers and working circuits is
the same as already described. The transformer T is shown connected with the
outside mains and feeding a lamp circuit, while transformers T T are shown
connected to the three mains and transforming polyphase currents suitable for
motors as well as lamps. The generator G2 supplies current only to the single-
phase translating devices, but it works in multiple as shown, with the generators G G
which are the source of polyphase currents.
Referring again to the construction of the generator the angle of displacement of
phase maintained in the main b depends upon the relative values of the component
electromotive forces due to the phase-modifying coil and the main coil. These

page_text: component forces may be illustrated geometrically as in Figure 5, where e represents,
for example, the electromotive force of one half the main winding A, e¹ representing
the electromotive force due to the other half A2 of the winding and e² the electro-
motive force due to the phase-modifying coil. The resultant electromotive forces
maintained between the main b and the mains ac will then be represented by e³ et. If
now the relative value of the components is changed, as for example, by increasing
the value of while maintaining e e¹ the same as is indicated in dotted lines,
the resultant electromotive forces will assume a different angular position, and
consequently the difference of phase will be correspondingly changed. To enable
the adjustment of the phase relation, means are provided for regulating the value
of the component electromotive forces. This may be accomplished in a variety of
ways needing no special description, but the simplest and preferred method will be
to wind the phase-modifying coil in sections, providing a switch for cutting more or
less of them into circuit.
In this Application the phase-modifying source of electro-motive force is
described as consisting of a supplementary coil on the generator. It is, however,
not necessary that the modifying source of electromotive force be connected with
the main source directly.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. The method of maintaining polyphase electromotive forces in the different
mains or branches of a polyphase distribution system, which consists in connecting
electrically or inductively two or more of such mains to the terminals of a main
source of electromotive force of the single-phase type, and similarly connecting
another of the mains to such source through a supplementary source of electro-
motive force of different phase relation, whereby such last mentioned source of
electromotive force gives rise to a desired difference of phase between the mains, as
described.
2. The method of maintaining polyphase electromotive forces in the different
mains or branches of a polyphase distribution system, which consists in inducing
alternating electromotive forces in a stationary or moving electro-dynamic
mechanism of the single-phase type, to whose terminals some of the mains are
electrically or inductively connected, and inducing an electromotive force of
different phase relation in a supplementary conductor connected to one or more
other mains, which acting to modify the first named electromotive force, creates
the desired difference of phase between the mains, as set forth.
3. The method herein set forth, which consists in maintaining polyphase electro-
motive forces between the different branches of a polyphase distribution system by
the combined action of a source of electromotive force of the single-phase type,
and a modifying source of electromotive force of different phase relation, and
adjusting the difference of phase by regulating the relative values of the main and
modifying electromotive forces, as described.
4. The method herein set forth which consists in maintaining between two
branches or mains of a polyphase distribution system, an alternating electro-
motive force by connecting them inductively or electrically with any ordinary
source of electromotive force of the single-phase type, and maintaining between
such mains and an additional main, electromotive forces out of phase with one
another and with that between the first named mains, which electromotive forces
are the resultants of the main source and a supplementary source of electromotive
force of different phase relation.
5. The herein described method, which consists in connecting a modifying source
of electromotive force to a point at or near the electrical centre of a main source
of electromotive force of the single-phase type, the modifying electro-motive force
· having a different phase relation and by its modifying influence creating a desired

page_text: difference of phase between the terminals of the main source and the free terminal
of the auxiliary source, as described.
6. The method herein set forth, which consists in maintaining an alternating
electromotive force between two branches or mains of an electric distribution
system connected respectively to the terminals of a main generator of electromotive
force of the single-phase type, and, for the purpose of securing multiphase currents
when desired, maintaining on a separate branch or branches of the systems an
electromotive force or displaced phase by the combined action of the said main
source of electromotive force and a supplementary source of electromotive force
having a different phase relation, and thereby modifying to the desired extent the
phase relation of the resultant electromotive force.
7. The combination of a generator or source of electromotive force of the single-
phase type and an electric circuit connected electrically or inductively therewith,
with a separate main or mains forming with the said circuit a multiphase distribution
system, and a supplementary or modifying source of electromotive force in circuit
with such last named main or mains tending to generate an electromotive force of
different phase from the main source, and thereby maintaining a displacement of
phase between the different mains suitable for the derivation of polyphase currents,
as described.
8. The combination of a main source of electromotive force of the alternating
single-phase type having its poles connected to mains forming part of an electric
distribution system, and a supplementary source of electromotive force of different
phase relation connected to an additional branch of the system, and serving with
the main generating source to maintain a resultant electromotive force on the main
to which it is connected, having a desired difference of phase from that developed
by the unmodified action of the main source.
9. The combination of main source of electromotive force of the single phase
type connected to some of the mains of a distribution system, and a modifying
source of electromotive force of different phase relation between such main source
and one or more other mains of the system, as set forth.
10. The combination of main and modifying sources of electromotive force of
different phase relation connected to and maintaining polyphase electromotive
forces in, the different branches of a polyphase distribution system, as described,
with lamps or other single phase translating devices supplied with current by the
.mains connected with the main source of electromotive force, and polyphase
motors or other like devices supplied with current from the mains connected with
both sources of electromotive force, as described.
11. A dynamo-electric machine having a main armature winding of the single-
phase type, and a phase-modifying coil connected to an intermediate point in the
main winding and occupying a displaced position in the field of force, as set forth.
12. A dynamo-electric machine having a main armature winding of the single-
phase type connected at its respective ends to collector rings or similar circuit
terminals, and a phase-modifying coil connected at one end to a point at or near the
electrical centre of the main winding and at the other end to a collector ring, as
.described.
13. The combination of a plurality of alternating current dynamo electric
machines coupled in multiple, one or more of such machines being provided with a
supplementary winding serving as a source of electromotive force of displaced
phase with single phase circuits extending from all the machines and multiphase
circuits extending from the machine or machines provided with the supplementary
winding.
Dated this 8th day of February 1895