Improvements in Apparatus for Exciting Alternating Current, Dynamos.
Year: 1899

page_text: Date of Application, 3rd July, 1899
Complete Specification Left. 25th Jan., 1900--Accepted, 17th Mar., 1900
DIEUITIVATION.
Improvements in Apparatus for Exciting Alternating Current,
Dynamos.
1, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings,
in the County of London, Consulting Engineer and Chartered Patent Agent,
do hereby declare the nature of this invention (as communicated to me from
abroad by La Société Anonyme pour la Transmission de la Force par l'Electricité,
of 13, Rue Lafayette, Paris, France, Manufacturers) to be as follows:―
This invention relates to an exciting apparatus whereby an alternating current
dynamo is made to furnish currents of constant intensity or constant voltage.
For this purpose, two armatures suited for continuous current are fixed on
one axis, their coil sections being connected to a commutator on the axis. The
connections of the one set of coils to the commutator segments are made in the
usual way, the coils of the other set are connected in shunt to those segments of
the commutator.which are symmetrical to it relatively to a certain plane passing
through the axis. Around one of the armatures is arranged an inductor such as
that of a continuous current machine, the field coil of which is connected in series
with the circuit traversed by the current supplied by the exciter. Around the
other armature are arranged two rings like the inducing rings of a synchronous
monophased or polypliases alternating current machine, the circuits of one of
these rings being connected in elunt to the conductors of the network which takes
the currents of the alternator, and the circuits of the other ring being connected
in series with the circuits of the armature of the alternator.
1.£T... 1900
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Exciting Alternating Current
Dynamos.
I, CILARLES DENTON ABEL,, of Birkbeck Bank Chambers, Southampton Buildings,
in the County of London, Consulting Engineer, and Chartered Patent Agent,
do hereby declare the nature of this invention (as communicated to me from
abroad by La Société Anonyme pour la Transmission de la Force par l'Electricité,
of 13, Rue Lafayette, Paris, France, Manufacturers), and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
'
This invention relates to an exciting apparatus whereby an alternating current

page_text: dynamo is made to furnish currents of constant intensity or constant voltage,
as I shall describe referring to the accompanying drawings.
Fig. 1 is a side view and Fig 2 is a section of an exciter according to this
invention. Fig. 3is a diagram of connections hereinafter referred to.
a and bare two armatures suited for. continuous currents on one shaft. These
armatures may have different numbers of sections and coils, but they are prefer-
ably equal and in what follows they are considered to be so. The sections of
these armatures are connected together and to the segments of a commutator c,
the connections being as shewn in Fig. 3, in which the number of the commu-
tator segments is the same as that of the sections of each armature, that is to
say in this case 12. The sections of a are-indicated by the cross hatched rect-
angles, those of 6 by the simply hatched rectangles. As shewn in Fig. 3 each
section of b is connected in parallel with the section of a, symmetrical with it
relatively to a diameter A B. Each of these 12 sections is connected in shunt
between two consecutive commutative segments as in an ordinary continuous
current machine.. Around the armature. a are arranged two rings d and e each
having a winding of an asynchronous bipolar munophase or polypliase "current
machine as the case may be. The circuits of d are connected.in series with the
corresponding circuits of the armature of the generating machine. The circuits
of' e are connected in shunt between these circuits of the generating machine..
This circuits of the rings de are relatively phased like the alternating current
circuits of the two rings of the exciter described in the Specification No: 22333
of 1896.
The sections of the magnetic circuits of the rings de should be determined in
such a manner that there is saturation in the one or the other when the voltage of
the alternator or its output have the values determined as indicated in the
Specification No. 22333 of 1896 for the magnetic circuits in which are developed
the fluxes produced by the alternating current circuits of the exciter.
The resulting flux developed by the rings d e varies with the output of the
alternator like that developed by the alternating current circuits of the exciter in
the Specification No. 22333 of 1896. But instead of being fixed in space it
turns around the axis y with the velocity of a revolutions per second and the
alternator produces currents of frequency a.
=
If there be two circuits and 4, Fig. 4, of the same number of turns connected
in opposition, each having inconsiderable resistances, when p is subjected to a
magnetising force producing in it a variable flux such as f¹ f sin 2. at, the
circuit is necessarily the seat of a flux f = f sin 2 at; the least differenca
between these two fluxes determines an electromotive force in the total circuit
comprising both and q, and this force acting on a circuit of inconsiderable
resistance produces there a dewatted current which reestablishes the equality
of the two fluxes, lessening the one to increase the other. Now the rings.n and b
are covered with a network of circuits having the same number of windings
opposed like P
and and symmetrically arranged relatively to the diameter A B.
Consequently to any variable flux developed in a there corresponds an equal flux
in having the opposite sign and a direction symmetrical with that in a rela-
tively to A B. To every flux turning with the velocity relatively to ring a
in the direction opposite to the rotation of a there is in the ring b a flux turning
with the velocity relatively to this ring but in the opposite direction, so that
this flux is stationary in space. Thus the inductive circuits of alternating
currents d and e develop in the ring a-flux stationary in space, the direction of
which depends only on the phase of movement of the resulting flux developed in the
inductors d and e and of that of the line of symmetry A B. The intensity of
the stationary flux equals that of the resulting flux.
'a'
2
'
":
°
113-
1
If the rings a and b and consequently, the line A B move forward, the direc-

page_text: tion of the stationary flux moves through angle equal to this movement in the
direction of the movement of the rings and inversely. Consequently it moves
relatively to the circuits which cover this ring like the corresponding flux of the
former exciter. If the exciter gives a continuous current collected outside by
brushes bearing on its commutator, these currents distribute themselves between
the two rings so that there is always equality of the fluxes of which the one in
ring is stationary in space and is directed in the line of the brushes, and the
other in ring a is always symmetric to it relatively to A B.
b
Finally the continuous current inductor of the ring 6 produces two equal
fluxes proportional to the output of the exciter, the one of ring b stationary in
space, the other in the ring a which moves relatively to it with the velocity
in the direction of its movement.
2
ル
J
(b
The fluxes developed in the ring b are the same as if this ring were furnished
with two alternating current circuits such as those of the former exciter, traversed
by currents of frequency when this ring revolves with velocity the phase of
the variation of the coefficients of mutual inductions of these circuits with the
continuous current inductor, advancing or retreating when the line of
symmetry A B advances or retreats. Thus the electromotive forces developed
in the continuous current circuit of the exciter are the same as those produced
in the corresponding circuit of the former exciter.
The ring a being the seat of the same fluxes as the ring b works under the
same conditions and the currents which it furnishes are collected by the same
commutator.
The velocity of the fluxes which traverse the rings d and' e being twice as
great as that of the same fluxes in a, the energy taken from the circuits of d
and e is twice that directly furnished by the circuits of a. The difference of
those two amounts of energy is communicated as mechanical work to the ring a
which expends it in causing rotation of the ring with it. Consequently the
new exciter acts exactly like the former.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner, the same is to be performed, I declare that what I
claim is:-
:
1. An exciter for developing constant voltage or currents of constant intensity
by an alternator, this exciter consisting substantially in the combination on one
axis of two armature rings of continuous current machines, the different sections
of which are connected in shunt to one commutator, for one of the rings the
connections being made as usual, and the sections of the other ring being con-
nected in shunt between the commutator segments which are symmetric with t
relatively to a certain diameter.
2. The arrangement around one of the rings of an ordinary continuous current
machine inductor, the field coil of which is connected in series with the circuit
of the current supplied by the exciter.
3. The arrangement around the other ring of two fixed rings like the inductor
rings of asynchronous monophase or polyphase alternating current machines, the
circuits of one of these rings being connected in series with the circuits of the
armature of the alternator, and the circuits of the other ring being connected in
shunt between the ends of these same circuits.
Dated this 25th day of January 1900.