Improvements in or connected with Rotary Electric Transformers.
Year: 1895

page_text: Date of Application, 13th Dec., 1895
Complete Specification Left. 19th Aug.. 1896-Accepted. 3rd Oct.. 1896
Date of Application, 13th Dec., 1893
Complete Specification Left. 19th Aug.. 1896-Accepted. 3rd Oct.. 1896
PROVISIONAL SPECIFICATION.
Improvements in or connected with Rotary Electric Transformers.
We, ALEXANDER BEWICKE BLACKBURN Manager of The Electric Construction
Company Limited of Wolverhampton in the County of Stafford and WILFRED
L. SPENCE of Dunluce Tettenhall Road, Wolverhampton aforesaid Civil Engineer
do hereby declare the nature of this invention to be as follows:-
This invention has reference more particularly to rotary transformers or motor
generators employed as balancing machines on a three wire or similar system of
electricity distribution (for the sake of clearness I will refer to it as a three wire
system) and it consists in a novel arrangement or combination of parts by means
of which the distribution of pressure is automatically varied to correspond directly
(instead of inversely as hitherto) with the load on the two circuits. According to
this invention this result is attained as follows.-
On a single armature core are carried the two main windings, one for each
circuit, the armature being common to both. Either one of these windings is
connected directly to its corresponding commutator, the other winding being passed
over a small subsidiary or regulating core before reaching its commutator.
The two armature cores are mounted a short distance apart on a single spindle
and rotate together in separate magnetic fields.
The main field is preferably excited as a shunt, and the regulating field is created
by a series coil connected on the one side to the junction between the two
commutators, which are in series across the outer wires, and on the other to the
third wire of the network, so that it carries in one direction or another, the
unbalanced current of the system. Calling the positive circuit with its armature (A)
and the negative circuit with its armature (B), the series coil is wound and
connected so that the action is as follows.—
If the circuit of A be overloaded then the armature of B will act as a motor
and the armature of A as a generator. Current will also pass from the middle
wire into the compensating field coil in such a sense as to reduce the counter
electro motive force of the circuit B thus raising the speed of the armatures and
augmenting the proportion of the electro motive force on the overloaded circuit.
If on the other hand the B circuit be overloaded then the armature of A will
act as a motor and the armature of B as a generator. The unbalanced current
will now flow in the reverse direction that is to say out into the middle wire, and
its effect through the compensating field, will be to increase the electro motive
force of the armature of B and therefore the proportion of the total electro
motive force on the corresponding side of the system.
Thus on whichever side the load is in excess that circuit will have its pressure
slightly augmented and the other circuit will get a somewhat lower electro motive
force.
In the foregoing description it is assumed that the armature of the B circuit
contains the regulating winding but it is immaterial which armature acts as the
special regulator so long as the series coil is connected to effect the appropriate
variation.
Dated this 18th day of December 1905
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: improvements in or connected with Rotary Electric Transformers.
We ALEXANDER BEWICKE BLACKBURN, Manager of The Electric Construction
Company Limited of Wolverhampton in the County of Stafford and WILFRID
L. SPENCE, of Dunluce, Tettenhall Road, Wolverhampton, aforesaid, 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 :-
This invention has reference more particularly to the rotary transformers, or
motor generators, employed as balancing machines on a three-wire, or similar,
system of electricity distribution (for the sake of clearness we will refer to it as a
three wire system), and it consists in a novel arrangement, or combination of parts
by means of which the distribution of pressure is automatically varied to correspond
directly (instead of inversely as hitherto) with the load on the two circuits.
According to this invention this result is attained as follows:-
On a single armature core are carried the two main windings, one for each circuit,
the armature being common to both. Either of these windings is connected directly
to the corresponding commutator, the other winding being passed over a small
subsidiary, or regulating, or compensating, core before reaching its commutator.
The two armature cores are mounted a short distance apart on the same shaft,
or spindle, and rotate together in separate magnetic fields. The main field is
preferably excited as a shunt, and the regulating field is created by a series coil
connected on the one side to the junction between the two armature windings, and
on the other to the third, or neutral, wire of the system, or network, so that it
carries in one direction, or another, the unbalanced current of the system. Calling
the positive circuit, with its armature, "A," and the negative circuit, with its
armature, "B," the action may be stated as follows:-If the A circuit be over-
loaded, then the armature of B, will act as a motor, and the armature of A, as a
generator. The current passing, as indicated by the arrows, in the diagram
Figure 2 of the accompanying drawings, from the middle wire into the com-
pensating, or regulating, field coil, will be in such a sense as, by proper connection,
to reduce the counter electro-motive force of the B armature winding thus raising
the speed of rotation and augmenting the proportion of the electro-motive force on
the overloaded circuit.
If, on the other hand, the circuit B, be overloaded, then the armature of A, will
act as a motor and the armature of B, as a generator. The unbalanced current
will now flow in the reverse direction, that is to say :-out into the middle wire, as
shewn by the arrows in the diagram Figure 3, and its effect, through the com-
pensating field, will be to increase the electro-motive force of the armature of B
and therefore the proportion of the total electro-motive force on the corresponding
side of the system.
Thus on whichever side the load is in excess that circuit will have its pressure
slightly augmented, and the other circuit will get a somewhat lower electro-motive
force. With the usual construction of balancing transformer the reverse effect
takes place, the side with heaviest load gets the least pressure, and, as a consequence,
such machines have had to be built much larger than is necessary in the arrangement
according to this invention to secure even better regulation.
C
Figure 1 of the accompanying drawings is a part section and part elevation of
the preferred arrangement according to this invention. The main and regulating
armature cores a and b are mounted on the same shaft c and rotate together but in
independent magnetic fields, the core a enveloped by both windings, in the shunt,
or constantly excited, field, and the core 6 carrying one winding only, in the middle
wire series field. The details of construction may otherwise generally resemble

page_text: those which are described and shewn in the Complete Specification of Letters.
Patent No. 11153 of 6th June 1895 granted to us.
It will be understood that we do not confine ourselves to the actual disposition.
shewn in the drawings, for instance, the auxiliary field instead of being entirely
distinct from the main field may be shunted from it, at, or near, the pole pieces.
In certain cases, owing to peculiar local conditions, it may be necessary to
maintain permanently the electro-motive force on one side of the system higher
than on the other, but this in a varying degree. Such an effect can be obtained
by a shunt winding on the regulating field in addition to the series excitation, and
further the use of hand regulation in combination with either; or both of the
aforesaid windings will afford a means of varying the amount of automatic control.
In general, however, the simpler construction is preferred.
The principal application of the machine will be in sub-stations, at, or near, the
remote end of the larger feeders, and, to a lesser extent, in generating stations.
Its use will entirely obviate the necessity for expenditure on copper for the middle
wire of feeders, and, by enabling the generators and switch gear to be arranged
for the full voltage across the outer wires, will effect further economies, both in
first cost and in the expenses of superintendence and regulation.
We are
aware of what has been accomplished in the way of balancing
transformers, and our present invention is designed to combine the advantages of
each of the hitherto commonly used types with freedom from their objections..
The mechanical efficiency of the double wound single armature core machine
running in two bearings is retained, together with the superior electrical regulation
rendered possible by the use of two entirely separate dynamos coupled shaft to
shaft.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what we
clain is :-
:-
In rotary transformers, or motor generators, employed as balancing machines
on three wire, or similar, systems; an arrangement having main and regulating
armature cores on the same shaft or spindle, the main armature core carrying two
main windings one for each circuit and rotating in a field of constant excitation
and the regulating armature core carrying one of these windings only and rotating
in a field excited by a coil in series with the middle wire of the system so that the
distribution of electrical pressure is automatically varied to correspond directly
with the load on the two circuits; substantially as herein before described.
Dated this 19th day of August 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.