Year: 1899

page_text: Date of Application (in United Kingdom), 1st June, 1899
Complete Specification Left, 1st Mar., 1900-Accepted, 7th Apr., 1900
I, CHARLES FELTON SCOTT, of 6214, Sellers Street, Pittsburgh, in the County
of Allegheny, State of Pennsylvania, United States of North America, Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to systems of electrical distribution, and has for its object
to provide an arrangement whereby two pairs of leads carrying alternating
currents in quadrature supplied by a polyphase generator may be
connected to three wires in such a manner that the currents circulating in said
three wires will be proper three-phase currents, that is to say, they will have
equal electro-motive forces, and will differ in phase by 120°.
In the accompanying drawing
Figure 1 is a diagram shewing a two-phase generator connected to three wires
in accordance with my invention, with single-phase, two-phase, and three-phase
translating devices connected to said three wires.
Figure 2 is a diagram of the electro-motive forces of the generator and distri-
buting circuit.
Referring to Figure 1, I is a two-phase generator having a closed coil armature
winding 2, the field-magnet winding 3 being energised by a suitable exciter 4.
Two terminals 5 and 6 of the armature winding of the generator, corresponding
to one phase of current, are connected respectively to the line conductors 7 and 8,
and two terminals, 9 and 10, taking a current having a phase angle difference of
90° from the first named current, are connected respectively to the terminals 11
and 12 of the winding 13 of a transformer 14. The secondary winding 15 of the
transformer 14 is connected to the terminal 12 of the primary, and therefore
to the terminal 10 of the generator armature, and the other terminal 16 of the
secondary. 15 is connected to the third line conductor 17 of the system.
-
The transformer 14 is so proportioned that the electro-motive force generated
by the secondary winding is that necessary for producing a proper three-phase
relation in the three line conductors. This relation will be preferably such that
the currents of the three phases will differ from each other by an angle of
approximately 120°.
In order to secure such relation it will be readily understood that the secondary
electromotive force of the transformer will be approximately 36.7 per cent. of
the normal electromotive force of the two-phase machine, and also of the three-
phase circuit.

page_text: I have shewn, by way of example, four varieties of translating devices supplied
from the three wires 7, 8, and 17, the devices 18 and 19 being three-phase
motors, 20 a two-phase motor and 21 single-phase translating devices such as
lamps for example. These devices are connected either direct to the wires 7,
S. 17 where the voltages are such as will properly operate the devices, or, as shewn
in the drawing, may be connected through the agency of transformers. These
methods of connecting one, two, and three-phase translating devices being well
known in the art, it is not necessary to describe them, and it will be understood
that I do not limit myself to the precise methods shewn in the diagram for con-
necting such translating devices.
In Figure 2 the line .....
represents the electro-motive force between
the terminals 5-6 of the generator, and therefore between the terminals of the
line circuit 7-8, and the line c.
7, the electro-motive force between
e,
the terminals 9-10 of the generator and consequently between the terminals of
the primary 13 of the transformer 14, the relative position of these lines indicat-
ing the phase angle relation between these currents and electro-motive forces.
The line.
e represents the electro-motive forces between the terminals
of the secondary 15 of the transformer, and consequently the lines a
b and b
e represent respectively the electro-motive forces
between the line conductors 7-17, and 7-8, and 8-17 The relative angular
position of these lines shews that the currents of the three-phase circuit are
separated by phase angles of 120°, as is desired in property balanced three-
phase circuits."
Improvements in Systems of Electrical Distribution.
I, CHARLES FELTON SCOTT, of 6214, Sellers Street, Pittsburgh, in the County
of Allegheny, State of Pennsylvania, United States of North America, Electrical
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 systems of electrical distribution, and has for its object
to provide an arrangement whereby two pairs of leads carrying alternating
currents in quadrature supplied by
be
polyphase generator may
al
connected to three wires in such a manner that the currents circulating in said
three wires will be proper three-phase currents, that is to say, they will have
equal electro-motive forces, and will differ in phase by 120°.
In the drawing left with my Provisional Specification,
Figure 1 is a diagram shewing a two-phase generator connected to three wires
in accordance with my invention, with single-phase, two-phase, and three-phase
translating devices connected to said three wires.
Figure 2 is a diagram of the electro-motive forces of the generator and distri-
buting circuit.
Referring to Figure 1, 1 is a two-phase generator having a closed coil armature
winding 2, the field-magnet winding being energised by a suitable exciter 4.
Two terminals 5 and 6 of the armature winding of the generator, corresponding
to one phase of current, are connected respectively to the line conductors i and S.
and two terminals, 9 and 10, taking a current having a phase angle difference of

page_text: 90° from the first named current, are connected respectively to the terminals 11
and 12 of the winding 13 of a transformer 14. The secondary winding 15 of the
transformer 14 is connected to the terminal 12 of the primary, and therefore
to the terminal 10 of the generator armature, and the other terminal 16 of the
secondary 15 is connected to the third line conductor 17 of the system.
The transformer 14 is so proportioned that the electro-motive force generated
by the secondary winding is that necessary for producing a proper three-phase
relation in the three line conductors. This relation will be preferably such that
the currents of the three phases will differ from each other by an angle of
approximately 120°.
In order to secure such relation it will be readily understood that the secondary
electromotive force of the transformer will be approximately 36.7 per cent. of
the normal electromotive force of the two-phase machine, and also of the three-
phase circuit.
I have shewn, by way of example, four varieties of translating devices supplied
from the three wires 7, 8, and 17. the devices 18 and 19 being three-phase
motors. 20 a two-phase motor and 21 single-phase translating devices such as
lamps for example. These devices are connected either direct to the wires 7,
8, 17 where the voltages are such as will properly operate the devices, or, as shewn
in the drawing, may be connected through the agency of transformers. These
methods of connecting one, two, and three-phase translating devices being well
known in the art, it is not necessary to describe them, and it will be understood
that I do not limit myself to the precise methods shown in the diagram for con-
necting such translating devices.
In Figure 2 the line a
represents the electro-motive force between
the terminals 5-6 of the generator, and therefore between the terminals of the
line circuit 7-8, and the line c.
d, the electro-motive force between
e,
the terminals 9-10 of the generator and consequently between the terminals of
the primary 13 of the transformer 14, the relative position of these lines indicat-
ing the phase angle relation between these currents and electro-motive forces.
The line
e represents the electro-motive forces between the terminals
of the secondary 15 of the transformer, and consequently the lines a
b and b
e represents respectively the electro-motive forces
between the line conductors 7-17, and 7-8, and 8-17 The relative angular
position of these lines shews that the currents of the three-phase circuit are
separated by phase angles of 120°, as is desired in properly balanced three-
phase circuits.
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:
The arrangement for supplying three wires with three-phase currents from two
pairs of leads supplied with alternating currents in quadrature from a polyphase
generator substantially as described with reference to the accompanying drawing.
Dated the 1st day of March 1000
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham.