Improvements in Dynamo Electric Generators.
Year: 1891

page_text: Date of Application, 11th May, 1891
Complete Specification Left, 5th Feb., 1892-Accepted, 5th Mar., 1892
PROVISIONAL SPECIFICATION.
Improvements in Dynamo Electric Generators.
I RANKIN KENNEDY Electrical Engineer Carntyne Electric Works Shettleston
Glasgow in the County of Lanark N.B. do hereby declare the nature of this
invention to be as follows:-
These improvements relate to dynamo electric generators more particularly for
generating alternating currents of electricity, and have for their object the con-
struction of a dynamo electric generator, generating alternating electric currents
having any desired frequency of alternations.
According to my invention all the coils of insulated wires are fixed and stationary,
the only rotary part being a series of laminated iron inductors, mounted on wheels
keyed to a spindle free to rotate. There is only one exciting coil, on the dynamo
electric machine according to my invention but this exciting coil is divided into
two equal divisions, connected together in series for the purpose of neutralising
inductive effects on the exciting circuit the inductive effect on the one division
being made opposite and equal to that on the other division.
The generating coil is also divided into two and the two divisions are
sometimes connected in series and sometimes act each independently as two
separate coils.
The coils exciting and generating are of ring shape, a generating and exciting
coil being bound together concentrically forming rings of insulated wire, they are
then placed in the machine inside of laminated iron blocks having recesses, forming
circular spaces, to receive the rings of wire & embracing three sides of the rings
of wire, which are square in section in a plane parallel to the axis. To form these
recesses for the wire coils the blocks of iron are built like transformers, of iron
stampings of U, E, or H form, and these blocks are equal in number to the desired
frequency of the alternating current to be produced per second or per revolution
of the inductors. As the inductors revolve they alternately open and close the
magnetic circuit of the iron blocks embracing the coils of insulated wires, there is
thus set up a variable magnetic flux through the coils, inducing alternating currents
on the secondary or generating coils, the primary coil being at same time excited
by a steady current. By using two series of inductors, and a divided exciting coil
I can neutralise the inductive effect on the exciting circuit, one series of inductors
are for this purpose adjusted to induce equally and oppositely to the other; this I
do by mounting them on separate wheels and setting one series in advance of
the other so that the one is on open magnetic circuit when the other is on closed
magnetic circuit.
If a frequency of twelve per revolution is required then twelve iron blocks are
placed round the rings of wire forming the generating and exciting coils.
The iron blocks are bound together in a circle by bolts and fixed in a cast
iron frame the blocks being spaced round the wire coils at equal distances from
each other.
According to my invention as herein described there is only two exciting and
two generating coils in the dynamo electric generator however great may be the
required frequency of the alternations of current, and both exciting and generating
coils are stationary and fixed and the alternating current is produced by opening
and closing the magnet circuits round the wire coils carrying the currents.
The primary or exciting coils are excited by a separate continuous current
machine or by any of the other well known methods.
Dated this Ninth day of May 1891.
RANKIN KENNEDY,
Carntyne, Shettleston, Glasgow.

page_text: COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Generators.
I, RANKIN KENNEDY, Electrical Engineer, Carntyne Electric Works,
Shettleston, Glasgow, in the County of Lanark, N.B., do hereby declare the
nature of my invention, and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement in
writing, that is to say :-
These improvements relate to dynamo electric generators more particularly for
generating alternating currents of electricity, and have for their object the con-
struction of a dynamo electric generator, generating alternating electric currents
having any desired frequency of alternations.
According to my invention all the coils of insulated wires are fixed and
stationary, the only rotary part being a series of laminated iron inductors mounted
on wheels keyed to a spindle and free to rotate. There is only one exciting coil on
the dynamo electric machine according to my invention but this exciting coil is
divided into two equal divisions connected together in series for the purpose of
neutralising inductive effects on the exciting circuit, the inductive effect on the one
division being made opposite and equal to that on the other division.
The generating coil is also divided into two, and the two divisions are
sometimes connected in series and sometimes act independently as two separate coils.
The coils exciting and generating are of ring shape, a generating and exciting
coil being bound together concentrically forming rings of insulated wires, they are
then placed in the machine inside of laminated iron blocks having recesses forming
circular spaces to receive the rings of wire and embracing three sides of the rings
of wire which are square in section in a plane parallel to the axis.
To form these recesses for the wire coils the blocks of iron are built of iron
stampings of UE or H form, and the blocks are equal in number to the desired
frequency of the alternating current to be produced per second or per revolution of
the inductors.
As the inductors revolve they alternately open and close the magnetic circuit of
the iron blocks embracing the coils of insulated wire. There is thus set up a
variable magnetic flow through the coils inducing alternating currents in the
secondary or generating coils, the primary coil being at the same time excited by a
steady current. By using two series of inductors and a divided exciting coil, I
neutralise the inductive effects on the exciting circuit, one series of inductors are
for this purpose adjusted to induce equally and oppositely to the other. This I do
by mounting them on separate wheels and setting one series in advance of the
other, so that the one is on open magnetic circuit while the other is on closed
magnetic circuit.
If a frequency of 12 per revolution is required these twelve iron blocks are
placed round the rings of wire forming the generating and exciting coils. The
iron blocks are bound together in a circle and fixed in a cast iron frame the blocks
being spaced round the wire coils at equal distances from each other.
According to my invention as herein described there is only two exciting and
two generating coils in the dynamo electric generator however great may be the
required frequency of the alternations of current. And both exciting and generating
coils are stationary and fixed and the alternating current is produced by opening
and closing the magnetic circuit round the wire coils carrying the currents.
The primary or exciting coils are excited by a separate continuous current
machine or by any of the other well known methods.
In order that others skilled in the art to which my invention relates may clearly
understand the nature of my said invention and the manner in which it is carried
into practice, I have hereunto appended two sheets of explanatory drawings showing
views of dynamo electric machines constructed according to my said invention
In

page_text: these drawings the same reference letters are used to indicate corresponding parts
in all the figures where shown.
Figure 1 on Sheet 1 is an elevation of a dynamo electric generator as constructed
in accordance with one arrangement of my improvements, and in which are shown
six laminated fixed iron inductors B to correspond with the equal number of
laminated iron blocks A secured on the rotating armature.
Figure 2 is an elevation, partly in section corresponding to and at right angles to
the view shown in Figure 1.
Figure 3 shows a detached view of an exciting coil P, and an inner generating
coil S, and the six fixed laminated iron blocks B which embrace these coils; and
Figure 4 is an edge view of the coils P and S.
Figure 5 is a detached elevation, and Figure 6 an end view, of one of the fixed
iron blocks B, which is built together of thin E shaped stampings or plates;
and Figure 7 is a face view of the same block B showing the recesses C, C¹.
Figure 8 is a side elevation partly in section of another arrangement of dynamo
electric generator in which the laminated fixed blocks B, and the movable
inductors A are placed radially instead of being parallel to the axis as in the
arrangement shown in Figures 1 to 7.
Figure 9 is a transverse section broken away corresponding to and at right
angles to Figure 8, showing the radial blocks B and the coils P and S.
Figure 10 is a section broken away as taken through one of the blocks B and
coils P, and S.
Figures 11 and 12 on Sheet 2 are an elevation and plan respectively of another
arrangement of dynamo electric generator in which the fixed blocks B, and movable
blocks A, are placed circumferentially, and are laminated at right angles to the
driving shaft W².
Referring to Figures 1 to 7 of these drawings, the iron blocks B are bound into
the cast iron frame F, as seen in Figures 1 and 2 and carry in their recesses the
generating and exciting wire coils S and P, as is clearly shown in Figures 3 and 4.
The wheels W, W', keyed to the shaft W2, carry the laminated inductors A.
These wheels W, W₁, have a channeled brass or manganese, steel rim into which
the laminated inductors A, are fixed by screw bolts A', as shown in Figure 1.
These wheels W, W', are mounted on the horizontal shaft W*, Figures 1 and 2,
and carry the inductors A, round in front of the iron blocks B, thus closing and
opening their magnetic circuit alternately.
In Figure 3 the terminals of the exciting coils P are shown at T, T, and the
terminals of the generating coils S at T¹, T. In cases where the generating
coils S, are used separately, the generating coil on the opposite side from that
shown in Figure 3 is connected to another pair of terminals.
To obtain an ordinary single alternating current from the machine and neutralise
the induction from the exciting coils P, the two exciting coils are connected in
series and so also are the two generating coils S, and the inductors A, on one
wheel W, are set opposite the spaces between the inductors A, on the other
wheel W, so that the iron blocks are on closed magnetic circuit one one side and
on open magnetic circuit on the other side, and at the same instant the current
generated in the one coil is opposite to that generated in the other coil, but they
are in same phase so may be coupled in series or parallel. And the induction in
the one exciting coil P, is opposite to that in the other exciting coil P, and as
they are coupled together in series so that the induction in the one is at any instant
exactly opposite to the induction of the other, both inductions are thereby
neutralised and the exciting current is steady and the generating coils are coupled
in series so that one end of S at any instant + while the end of the other
coil S connected to said end is
The exciting coils P, P, are coupled in series so that the two ends joined
together would be of same sign + or - at same instant under the induction.
Alternating currents of any desired difference of phase can be obtained from the
dynamo electric machine according to my invention by adjusting relative positions

page_text: of the inductors. This can be done by making the wheels W, or W₁, movable on
the shaft W2 and fixing them with pinching pins at any desired position, for instance
by fixing the one wheel so that its inductors are opposite the spaces between the
inductors on the other wheel. The alternating currents induced in coils are of
same phase again but of exactly opposite sign so that they may be coupled in series
or in parallel or used separately, by fixing the wheels so that the inductors are
midway between the two foregoing described positions. The current in one pair of
coils is in quadrature with the current in the other pair of coils.
The machine when used with the two currents in series or parallel or separately
and in same phase is according to my improvements worked with the inductors on
one wheel opposite the spaces between the inductors on the other wheel so that the
neutralising effects of induction are obtained in the exciting coils.
According to my invention there is no reversal of magnetism in the iron
magnetic circuits, and two machines are combined on one shaft for the purpose of
obtaining two alternating currents in quadrature and still have no inductive effects
in the exciting circuits.
Referring to Figures 8, 9 and 10;-In this arrangement the inductors A, Figure 8,
are secured radially in gun metal rings R, R₁, fixed to the driving shaft W², and
the fixed laminated blocks B, are carried radially in a cast iron split ring R², the
coils S, P, being let into the recesses C, C¹, as shown in Figures 9 and 10. The
movable inductors A, in the one wheel are fixed so that the magnetic circuit of the
blocks B is closed at the same instant that the inductors A in the other ring
are in complete open magnetic circuit. In other respects this arrangement is
analogous to that shown in Figures 1 to 7, and may be operated in the same
manner.
These
In the modification of the dynamo electric generator shown in Figures 11 and 12
the two pairs of coils P and S are set into the laminated iron fixed blocks B,
which are formed of E shaped stampings or plates. The blocks B are fixed on a
frame F, and present curved polar faces to the rotating inductors A.
rotating inductors A, are fixed by bolts A', passing through lugs and are
bolted between two steel discs W, carried on a spindle W2, revolving between
bearings W"
The exciting coils P are shown as thick wire, one in section and the other in end
view.
The generating coils S, are shown in section and in elevation as fine wire.
This machine operates in a precisely similar manner to that described for the
other forms Figures 1 to 10, and the exciting coils P are coupled in series so
that any inductive effects in the one are neutralised by that in the other.
The generating coils S are coupled either in parallel or in series.
The inductors A are made equal in number to the required frequency per
revolution. If four alternations per revolution are required then four inductors A,
are fixed in the wheel W, as shown in Figure 11. Of course more than
two E shaped blocks B carrying coils S and P, may be fixed around the inductors A.
In the machine illustrated there may be other two blocks B on a diameter at right
angles to the two shown. And by placing these blocks B at various other angles
to each other, currents of different phases may be obtained from the machine; and
for example if a pair of blocks B carrying coils S and P, similar to those shown
in thick lines Figure 11, be placed on a diameter, as shown dotted in in Figure 11,
making an angle of 67 degrees with the diameter 1-1 on which the block B,
shown in Figure 11 are placed, then two currents in quadrature phase would be
obtained one from each pair of blocks and coils.
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 :-
First. In a dynamo electric generator, the method of generating an alternating
current of any frequency in one or more coils of wire by placing iron blocks round

page_text: the coil or coils, exciting magnetism in said blocks by another coil or coils and
moving inductors near said blocks to open and close their magnetic circuit without
reversal of their magnetic poles thereby generating currents alternating at a
frequency per revolution equal to the number of blocks on the coil or coils, sub-
stantially as and for the purposes herein described in reference to and by way of
application shown in the accompanying drawings.
Second. In a dynamo electric generator wherein there is no reversal of magnetic
flow or poles, the use of exciting and generating coils fixed in laminated iron blocks,
in combination with movable laminated iron inductors which alternately open and
close the magnetic circuits around the coils, substantially as and for the purposes
herein described in reference to and by way of application shown in the accompanying
drawings.
Third. In a dynamo electric generator wherein there is no reversal of magnetic
flow or poles, the combination comprising generating and exciting coils in pairs,
with a separate series of inductors for each pair, the exciting coils of one pair
being connected in series with the exciting coils of the other pair, for the purpose of
neutralising inductive effects in said coils, the inductors acting on the one pair being
on open magnetic circuit at the instant the other pair are on closed magnetic circuit,
substantially as and for the purposes herein described, in reference to and by way
of application shown in the accompanying drawings.
Fourth. In a dynamo electric generator wherein there is no reversal of magnetic
flow or poles, the combination comprising laminated iron fixed blocks in which are
placed pairs of coils, with laminated iron inductors carried on the circumference of
a wheel, the magnetic circuit of said blocks being opened and closed by said
inductors to produce alternating currents in the generating coils, having the same
phase but opposite in sign in opposite coils on the same diameter, and having the
exciting coils coupled in series so that the inductive effects in said exciting coils
oppose each other, substantially as and for the purposes herein described, in
reference to and by way of application shown in the accompanying drawings.
Fifth. In a dynamo electric generator wherein there is no reversal of magnetic
flow or poles the combination comprising two or more pairs of coils on fixed
laminated iron blocks with two or more sets of movable inductors, the one set being
adjusted at an angle in advance of the other set for the purpose of producing
alternating currents of different phase, substantially as and for the purposes
herein described in reference to and by way of application shown in the accom-
panying drawings.
The 1th Wahmane 1000
W. R. M. THOMSON & Co.,
96, Buchanan Street, Glasgow, Agents.