Improvements in Electric Meters.
Year: 1899

page_text: Date of Applicatio n, 17th Oct., 1899-Accepted, 3rd Feb., 1900
Improvements in Electric Meters.
We, THE BRITISH THOMSON-HOUSTON COMPANY LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of our
said invention (which has been communicated to us from abroad by Elihu
Thomson, of Swampscott, in the County of Essex, State of Massachusetts, United
States of America, Electrical Engineer), 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 electric meters, and more particularly to those which
are used with alternating current and operated by induced currents, the armature
having no direct connection with the mains. It has for its object to provide a
simple meter of reasonable accuracy, which will be easily and cheaply made.
The essential features of the meter consist of a current coil and a potential coil.
each acting upon its own armature, the two armatures being so arranged as to
impart motion to a single shaft, and having their windings displaced relatively
to one another, or the fields being so displaced and the coils of the armatures
being parallel; it being manifest that this would be a substantially equivalent
arrangement. The coils on the armatures are electrically connected. We may,
if preferred, increase the inherent displacement of phase between the currents in
the shunt and series coils by any well known device. Any suitable counting
device or register and damping mechanism may be employed.
The accompanying drawings show our invention. Fig. 1 is a diagrammatic
elevation showing the meter connected in circuit; Figs. 2 and 3 are side eleva-
tions showing two different arrangements operating on substantially the same
principles; Figs. 4 and 5 show alternative methods of winding the armatures.
In Fig. 1 the current coil C is connected in one of the mains a, b; the potential
coil B, of fine wire and many turns, is connected across the mains, and in series
with it we prefer to place an inductive coil I serving to further displace the
phase between the current in the shunt coil and that in the main circuit. A
starting coil K is connected in parallel across the mains, and is arranged to be
substantially coincident in plane with the current coil. The starting is of just
sufficient effect to counter-balance the friction of the meter, and thus increase
its accuracy on small loads, where friction is not neglible. Lamps L represent
any form of translating device. A disc D of copper or other good conducting
metal revolves as a damping mechanism between the magnets M, M; other
equivalent forms of damper might be used.
A', A are the armatures of the meter, located upon the shaft S. They might
be geared to the shaft without departing from our invention, and many different
mechanical arrangements to this end might be made these expedients are well
known in meter construction, and need not be illustrated or more fully described.
The windings of the two armatures are illustrated in Figs. 4 and 5. These
windings are interconnected, the wires passing near the shaft as shown in the
figure, and forming what might be called a polyphase transmission between
the armatures. In Fig. 4 the arrangement is shown as consisting of coils c¹, c², c².
39

page_text: The coils in Fig. 4 are wound in parallel planes, but are so interconnected that
they are electrically displaced from one another, that is, the plane of the coil c
on armature A is displaced from the plane of the coil con armature A2 by an
angle 60 degrees or by an angle. of 120 degrees, depending upon the direction
in which the angle is measured.
The arrangement in Fig. 5 might also be adopted, where two phases only are
employed, and this is in some respects simpler than that shown in Fig. 1. In
this case the coils are displaced from one another 45 degrees in plane."
In Figs. 2 and 3, we show the mechanical disposition of the field magnet coils
and armatures, Fig. 2 showing the arrangement of Fig. 4. In this figure the
parts are lettered as before, the field coils C and B being in parallel planes, and
the displacement of the armature being effected by the connection of the windings,
as in Fig. 4. As an alternative construction we may adopt that shown in Fig. 3,
in which the field coils C and B are displaced in plane so that their flux cuts the
armatures at different angles. In this case, as already intimated, the armatures
themselves may, if desired, be wound with their coils in parallel planes.
The operation of the meter is as follows: if the armature A¹ be in its plane of
maximum induction, that is, parallel with the current coil C, the armature A²
will have its coils at an angle with the field coil B. In this case the current in C
induces in A¹ an electro-motive force which sends current through the closed
circuit of the two armatures, they being closed-circuited through each other;
the coils on A2, being at an angle with the plane of the coils B, tend to move.
When the coils A' are by this rotation turned out of inductive relation to the
coil C, the coils on A² have come into position of greatest induction with the
coils B, sending current through the winding of A¹, causing it to rotate; this
rotation of the shaft S is communicated to the counting device R, giving a
substantial indication of the power or watts derived from the mains a, b.
Having now particularly described and ascertained the nature of our said
invention (as communicated from abroad) and in what manner the same is to be
performed, we declare that what we claim is:-
1-An induction watt-hour meter for alternating currents, comprising a
current coil, a potential coil of phase displaced from that of the current coil,
and two armatures upon the same shaft coacting to impart torque thereto and
respectively within the fields of the current and potential coils.
2 An induction watt-hour meter for alternating current circuits, comprising
a current coil in series in the work circuit, a potential coil in, shunt to the work
circuit, and two armatures upon the same shaft having windings electrically
connected, but displaced relatively to one another.
3-An induction watt-hour meter for alternating current circuits, comprising
a current coil in series in the work circuit, a ✓otential coil in shunt across the
work circuit, with means for increasing the displacement of phase between the
electro motive force and current, and a pair of armatures disposed respectively
within the fields of the current and potential coils and coacting to impart torque
to the shaft.
4 An induction watt-hour meter, for alternating current circuits, comprising
a current coil, a potential coil of phase displaced from the current coil, and two
armatures respectively within the field of the current and shunt coils, the wind-
ings of the armatures electrically connected and angularly displaced from one
another.
5 In an electric watt-hour meter, the combination of current and potential
coils generating independent fields of force, with two armatures disposed upon
the same shaft and respectively situated in the fields of force of the two coils.
6 In an electric meter, the combination of a rotatable closed conductor, a
current coil and a potential coil with their magnetic axes in the same plane,
both coils being located in proximity to said conductor and arranged so that
when one coil acts inductively upon said conductor, the other acts dynamically

page_text: 7-An induction meter having an induced member, a current coil, a potential
coil and a starting coil, the magnetic axes of the current coil and potential coil
being in substantially the same plane.
8 In an electric meter, the combination of a rotatable closed conductor,
current and potential coils with their magnetic axes in substantially the same
plane, the closed conductor being located in proximity to said coils and so
arranged that the portions of the conductor acted upon by the respective coils
are angularly displaced from each other.
9 In an electric meter, the combination of a rotatable closed conductor,
and current and potential coils with their magnetic axes in substantially the
samne plane, and located in proximity to said closed conductor, the closed con-
ductor being provided with paths for current so arranged that current induced
by one of said coils is acted upon dynamically by another coil.
10 In an electric meter, the combination of a rotatable closed conductor,
and current and potential coils acting on said conductor and arranged so that the
respective magneto-motive forces produced thereby act upon the conductor
through paths substantially parallel with each other.
11 In an electric meter, the combination of a rotatable closed conductor,
and current and potential coils acting on said conductor and arranged so that the
respective magneto-motive forces produced thereby act upon the conductor
hrough paths substantially parallel with each other, while the currents induced
in said conductor are constrained to follow paths asymmetrical with respect to
said coils.
Dated this 17th day of October 1899.
THE BRITISH THOMSON-HOUSTON CO. LTD.,
ALFRED CLEMENTS,
Assistant Secretary.
J. J. MANHEIM,
W. MARTINDALE,
Directors.