Improvements in Dynamos, Motors, and Alternators.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Dynamos, Motors, and Alternators.
I, LLEWELYN BIRCHALL ATKINSON, of Bank Buildings, St. Mary Street,
Cardiff, in the County of Glamorgan, Civil Engineer, do hereby declare the
nature of this invention to be as follows:-
My invention relates to improvements in dynamo electric generators and motors,
and is applicable either to continuous current machines or to alternators, or to
multiphase machines, and has for its object the diminishing of the effective coefficient
of self-induction of the armature coils, and also the minimizing or varying the effect
of the armature reaction.
This invention is applicable to any dynamo, in which the coils are massed or
collected into "separate coils, in which case, where continuous currents or multi-
phase currents are required, there must be more than one set of coils differently
placed with respect to the poles of the field magnet, or the number of field
magnet poles must be a multiple of the number of armature coils, plus or
minus one.
My invention consists in winding upon the field magnet poles, through which the
induction with no current in the armature should be steady, short circuited copper
windings; or surrounding the same with copper castings, or placing copper bars,
or bolts through notches or holes in the pole pieces.
Any change in the magnetic induction passing through the poles, which change
is the measure of or effect of either armature reaction, or self-induction (other than
the self-induction of the coil, considered as a coil without a complete iron magnetic
circuit) is resisted by the current set up in these short circuited coils, and by making
the section of the conductor sufficiently large the variation in induction may be
reduced to any required amount.
In the case of alternators where the variation in the phase of the current from
the phase of the electro-motive force, due either to self-induction in the dynamo
itself, or in the external circuit, is to be diminished, or in some cases, increased, in
order to control or vary the armature reaction, I provide a separate field magnet
acting on the armature coils, or coils in series with them, and supplying an electro
motive force differing by phase from the main E.M.F. and proportional to the
current given by the machine, and adjustable as to amount, so that this E.M.F.
may be in phase with and proportional to the E.M.F. of self-induction, and may
either balance it, or increase, or diminish it.
Dated this 25th day of June 1895.
FELL & WILDING,
1 Queen Victoria Street, London, E.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Dynamos, Motors, and Alternators.
I, LLEWELYN BIRCHALL ATKINSON of Bank Buildings, St. Mary Street,
o Cardiff, in the County of Glamorgan, Civil Engineer, 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:-
My invention relates to improvements in dynamo electric generators and motors

page_text: and is applicable either to continuous current machines or to alternators or to
multiphase machines, and has for its object the diminishing of the effective
co-efficient of self induction of the armature coils, and also the minimizing or
varying the effect of the armature reaction.
This invention is applicable to any dynamo, in which the coils are massed or
collected into separate coils, in which case, where continuous currents or multiphase
currents are required, there must be more than one set of coils differently placed
with respect to the poles of the field magnet, or the number of field magnet poles
must be a multiple of the number of armature coils, plus or minus one.
My invention consists in winding upon the field magnet poles, through which
the induction with no current in the armature should be steady, short circuited
copper windings; or surrounding the same with copper castings, or placing copper
bars, or bolts through notches or holes in the pole pieces.
Any change in the magnetic induction passing through the poles, which change
is the measure of or effect of either armature reaction, or self induction (other than
the self-induction of the coil, considered as a coil without a complete iron magnetic
circuit) is resisted by the current set up in these short circuited coils, and by
making the section of the conductor sufficiently large the variation in induction
may be reduced to any required amount.
In the case of alternators where the variation in the phase of the current from
the phase of the electro motive force, due either to self induction in the dynamo
itself, or in the external circuit is to be diminished, or in some cases, increased in
order to control or vary the armature reaction, I provide a separate field magnet
acting on the armature coils, or coils in series with them, and supplying an electro
motive force differing by phase from the main E.M.F. and proportional to the
current given by the machine and adjustable as to amount, so that this E.M.F.
may be in phase with and proportional to the E. M. F. of self induction and may
either balance it, or increase, or diminish it.
And in order that my invention may be the better understood I will now proceed
to describe it in relation to the accompanying drawings hereunto annexed reference
being had to the letters and figures marked thereon.
Thus in Figure 1, A. B. C. D E are coils of an alternator shown wound in
recesses in a laminated iron ring. F. G. H. are pole pieces excited by
coils J. K. L, the magnets in this case revolving inside the armature.
The
pole piece ends.next the armature surface are shown constructed in accordance
with my present invention, thus F has a short circuited winding or enclosing
piece of conducting metal M, completely surrounding it, G has in addition a
central conductor N, connected to the enclosing conductor, whilst H shows the
whole surface intersected by conducting bars as P, all joined up by the enclosing
conductor. The effect in each case is similar. The induction through F. G. H is
maintained steady, notwithstanding the variation of magnetizing force due to
variation of current in the armature coils A. C. E., by the current induced in the
short circuited windings, resisting any change of induction. This construction is
also applicable, to multiphase machine or machines of a similar type used with a
commutator for producing continuous currents; where the number of coils or pairs
of coils on the armature differs by one from the number of magnet poles or pair of
magnet poles. Where however the self induction exterior to the machine gives
rise to a difference of phase between the current and the E.M.F. there will, not
withstanding the above construction be a variation in the average induction passing
through the poles F, G, H, which it is the purpose of the second part of my inven-
tion to deal with. This variation will where the phase of the current lags behind
the phase of the E.M.F., be a diminution of effective induction. And my invention
provides either for bringing the current into phase with the main E.M.F. or for
making the current phase lead in advance of that of main E.M.F. by which means
the induction may if necessary be increased, a result useful where there is a loss of
E.M.F. in the line served by the machine.
In order to make my invention clear, reference may be had to the vector diagram,

page_text: Figure 2, where UA is the main E.M.F. set up by the generator AC is the E.M.F..
of self induction OC is the resultant E.M.F. with which the current coincides each.
represented in phase and magnitude by the vector described.
In order that the phase of the current may co-incide with OA, I provide an
E.M.F. displaced period with respect to OA, proportional to the current, so as
to balance A C. The diagram then becomes, where A B is this E.M.F. as
Figure 3 where OA coincides with OC, showing the phase of E.M.F. and of
current coincident.
By regulating the E.M.F. A B in manner to be bereinafter described A B
may be made greater than the E.M.F. of self induction when the diagram will
become as Figure 4 where OA is the main E.M.F. A B the subsidiary E.M.F..
CB the E.M.F. of self induction and OC the resultant with which the current
coincides.
Thus these figures show how by means of a subsidiary E.M.F. proportional to
the current, and in phase leading in advance of the main E.M.F. the phase of the
current with respect to the E.M.F., may be made to coincide, or lead, or lag by an.
amount which can be regulated.
In order to carry this invention out, I provide subsidiary pole pieces acting
either upon the main coils, or upon coils connected to the main coils preferably in
series, and I excite these poles, either by the main current passed through a com-
mutator so as to be unidirectional or by a current maintained equal to or proportional
to the main current by hand or automatic regulation, these subsidiary poles being so.
placed that the phase of E.M.F. produced by them differs, (usually leading by
period) from the phase of the main E.M.F. This method may be shown by a.
diagram as in Figure 5 the direction of motion being as indicated by the arrow X..
Where A is the main magnet pole, shown at the position relative to the main coil a
where the E.M.F. is zero B is the subsidiary pole piece shown at the position.
relative to the subsidiary coil where the E.M.F. is at a maximum and leading
by period on the phase of the E.M.F. in a.
The pole A is excited in any usual manner, such as by coil C supplied by current
from exciter E, with a shunt wound magnet D.
B is excited by coil F shown supplied by current from the alternator mains,.
through a commutator G for reversing the ends of the coil F, relative to the
mains M M as the current reverses.
By this invention not only may the effect of self induction in the circuit,.
producing a difference of phase between the current and E.M.F. be obviated.or
modified as relates to its action in producing a decrease of active induction, but
by the use of a machine so constructed, important advantages arise in economy of
power transmission.
The power delivered to or received from an alternating current electric circuit
is expressible as the product of the virtual E.M.F. into the virtual current multiplied
by the cosine of the angle of lag. If therefore the maximum pressure is fixed, and
the power to be delivered fixed, the current will be a minimum when the current
and E.M.F. are in phase. By the use of this invention this result may be
secured.
In order to regulate the E.M.F. of the subsidiary coils the current in the
exciting coils of the subsidiary pole pieces may be regulated by transformers,.
resistances or shunts in any of the well known methods.
Although I have described an E.M.F. applied at a displacement of period from
the main E.M.F., other displacements will have a similar effect and may for some
purposes be preferable. As for example when the construction of the machine
does not conveniently allow of the placing of the subsidiary poles at period
displacement, or when the curve of E.M.F. given by the machine is not as here
assumed a sine curve so that a better effect is obtained by more or less than period
displacement.
Further whilst the descriptions given refer to generators of electric current, it.

page_text: will be understood that the improvements are applicable to such machines when
used as motors.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1st. In electric generators or motors having armature conductors massed or
collected into groups, the combination with such armature conductors and with
magnet pole pieces, of short circuited windings or conductive circuits placed in
or upon or around the pole piece substantially as and for the purpose described.
2nd. In alternating electric generators or motors the combination with a principle
source of alternating currents, of a subsidiary source of alternating current differing
in phase for the purpose of changing the phase of current relative to the E.M.F.
3rd. In alternating electric generators or motors as claimed in Claim 2 the com-
bination of a principle magnetic field and armature coils with a subsidiary magnetic
field also acting on the armature coils producing an E.M.F. differing in phase from
the principle E.M.F. substantially as and for the purposes described.
4th. In alternating electric generators or motors as claimed in Claim 1 the
combination of a principle magnetic field and armature coils with a subsidiary
magnetic field, and subsidiary coils connected to the principle coils producing an
E.M.F. differing in phase from the principle E.M. F. substantially as and for the
purpose described.
5th. In alternating electric generators or motors the construction and arrangement
of parts and circuits substantially as illustrated in Figures 1 and 5.
Dated this 10th day of March 1896.
FELL & WILDING,
1 Queen Victoria Street, London, E.C., Agents for the Applicant.