Improvements. in and relating to Dynamo-Electric Machines: and Rotary Converters.
Year: 1897

page_text: Date of Application, 8th June, 1897-Accepted, 31st July, 1897
Improvements. in and relating to Dynamo-Electric Machines: and
Rotary Converters.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED; of 83. Cannon Street; in
the City of London, Electrical Engineers do hereby declare the nature of this
invention (which has been communicated to us from abroad by Edwin W. Rice, Junior,
of Schenectady, 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 dynamo-electric machines,. especially. to such machines
when used as rotary converters of the polyphase or single-phase type, by means of
which alternating currents are converted into continuous, or vice versa, the outgoing
currents being then utilized for any purpose to which they may be applicable. The
invention is in part applicable to dynamo electric machines of any type. It has for
its object to balance the armatures of such apparatus, using the term in its electrical
sense, so that their action is improved and the commutation is effected with more
facility.
To accomplish the ends pointed out, we preferable use a single-wound armature of
the now well-known "Bradley" type. This may be either a ring or a drum winding
without affecting our invention; we have shown.it in the accompanying drawings as a
ring winding, but this is an immaterial feature. The armature is provided upon one
side with a commutator of a suitable number of segments for the winding chosen, and
upon the other side with collector rings for the alternating current. The collector
rings are connected to suitable points in the winding, in the case of three-phase
machines at 120 degrees apart; in a two-phase apparatus they would of course
be 90 degrees apart. To obtain the improved balancing to which we have referred we
also connect all of the equi-potential points around the armature, either by leads
passing from one point to another, one of such leads being connected to the collecting
ring, or we connect each of the equi-potential points to the collecting ring by a
separate lead, the collecting ring thus becoming an equalizer. It is of course intended,
in speaking of the angular difference of position of the connected points, to refer
to the polar pitch of the machines; that is to say, each cycle being taken
at 360 degrees.
The accompanying drawings show our invention, Fig. 1, being a side elevation of
our improved converter, and Figs. 2 and 3 being explanatory diagrams of the
connections; Fig. 2 shows the invention applied to a four-pole machine, and Fig. 3 to
one of eight poles.
A is the base of the machine; B, B are the parts of the field magnet frame; C, Care
the pedestals; D is the usual lifting ring applied to the upper part of the field
magnet; E, E², Es are the collecting rings; F is the armature, and G is the
commutator. No special feature of novelty is embraced in the mechanical construction
of the machine.
Referring to Fig. 2, we show how the equi-potential parts of the armature are
connected. We have illustrated, as will be apparent, a three-phase machine having
four poles, N, S &c. The number of points in the armature winding tapped is the

page_text: number of phases into the number of pairs of poles. In the case illustrated there
would be of course six points at which the armature winding would be connected
according to our invention. These points are numbered consecutively 1 to 6 around
the armature winding of and two of them would be connected to each of the
collector rings. The points 1 and 4 are connected to the ring E2; points 2 and 5
to the ring E points 3 and 6 to the ring E³.
Referring now to Fig. 3, we show the application of the invention to an eight pole
machine, using also the three-phase construction. In this there would be four pairs
of pole pieces and three phases, and consequently there would be twelve points around
the commutator. Points 1, 4, 7 and 10 are connected to the ring E2; 2, 5, 8 and 11
to the ring E3; and 3, 6, 9 and 12 to the ring E¹.
In the case of converters of different numbers of poles, the same principle may be
easily applied, various numbers of points of the winding being interconnected,
according to the number of poles and number of phases, as already pointed out.
Having now particularly described and ascertained the nature of our said 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. An armature for dynamo electric apparatus of the alternating current type,
comprising a winding and collecting rings, each collecting ring connected to leads
equally spaced around the armature winding and connecting equi-potential points of
each phase to one of the collecting rings.
2. A rotary converter comprising an armature and surrounding field poles, the
armature winding connected upon one side to a commutator, and upon the other side
to collecting rings, the equi-potential points of the armature winding for each phase
being connected to a collecting ring.
ed this 8th day or June 1897.
For the Applicant,
J. C. CHAPMAN,
70 Chancery Lane, London, W.C., Chartered Patent Agent.