Improvements in Electricity Meters for Alternating or Interrupted Currents.
Year: 1890

page_text: Date of Application, 21st Aug., 1890
Complete Specification Left, 19th June, 1891-Accepted, 21st Aug., 1891
PROVISIONAL
SPECIFICATION.
Improvements in Electricity Meters for Alternating or Interrupted
Currents.
I GEORGE HOOKHAм of Nos. 7 & 8 New Bartholomew Street Birmingham,
Manufacturer do hereby declare the nature of this invention to be as follows: -
My invention relates to improvements in that class of electro-motors in which
motion is communicated to a metallic disc, or other solid of revolution, commonly
called an armature, by the reaction of currents induced in the disc, the circuits of
such currents being completed within the disc, and in the combination of such a
motor with an electric brake similar to that described in the Complete Specifi-
cations of Letters Patent granted to me, & numbered 4225/87 and 17502/87
respectively.
My invention has for its object, first to produce a motor of the class indicated in
which the driving force shall be directly proportional to the current or energy to
be metered. I may obtain this proportionality in one of several ways. If a screen
is used as in the experiments of Elihu Thomson, I may obtain proportionality by
movements of the screen, such movements being regulated by the current (or energy)
to be metered. In this case the primary current inducing currents in the disc may
either be proportional to the current to be metered, or to the E.M.F. of the
supply, the movements of the screen in each case being regulated accordingly. For
the present purpose the E.M.F. of the supply may be assumed constant.
Or I may obtain proportionality by the movements of iron in the field, such
movements being so regulated by the current to be metered as to give proportional
driving; or the iron in the field may be stationary, but its magnetic state regulated
by the current to be metered.
Or, finally, I may place a conductor or conductors carrying the current to be
metered (or a current derived from & proportional to it) in proximity to those
parts of the disc in which induced currents are being generated in such a way that
the two sets of currents may re-act the one on the other. The conductor carrying
the current to be metered is preferably wound in such a manner as to lie in part
under the poles of the shunt-magnet.
The motor may have a bobbir.-shaped armature, the edges of the discs forming
the sides of the bobbin dipping into mercury; thus forming a closed circuit at the
point where they dip. One pole of a laminated bar-magnet is introduced between
the discs at this point to such an extent that the repulsion is just counterbalanced
by the initial friction.
Either to the disc of the motor or to another disc on the same spindle I apply a
permanent magnet forming an electric brake as described in my before-mentioned
Specifications, together with a counting-gear.
Dated this 10th day of A 1000
GEORGE HOOKHAM.
COMPLETE SPECIFICATION.
Improvements in Electricity Meters for Alternating or Interrupted
Currents.
I GEORGE HOOKHAM of Nos. 7 and 8 New Bartholomew Street Birmingham
Manufacturer 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 :-
My invention relates to improvements in electricity meters for measuring

page_text: alternating currents and also for measuring interrupted or intermittent currents.
The class of meter to which my improvements are applicable consists of an electro
motor in which the current to be measured communicates rotary motion to a metallic
dise or other solid of revolution commonly called an armature the rotation of the
said disc being produced by the reaction of currents induced in the said disc the
circuits of the said currents being completed within the said disc. My invention
further consists in coinbining with a. motor of the kind referred to a brake of the
kind described in the Complete Specifications of Letters Patent granted to me
No. 4225 dated 21st March 1887 and No. 17502 dated 20th December 1887.
My invention has for its principal object to produce a motor of the class indicated
in which the driving force shall be directly proportional to the current or energy to
be measured.
I obtain this proportionality in several ways. If a screen is used as in the
experiments of Elihu Thomson I obtain proportionality by movements of the screen
such movements being regulated by the current or energy to be measured. In this
case the primary current inducing currents in the disc may be proportional either
to the current to be measured or to the electro-motive force of the supply the
movements of the screen in each case being regulated accordingly. I will assume
the electro-motive force of the supply to be constant.
Or I obtain proportionality by the movements of iron in the field such movements
being so regulated by the current to be measured as to give proportional driving
force; or the iron in the field may be stationary and its magnetic state regulated
by the current to be measured.
Or I place a conductor or conductors carrying the current to be measured or a
current derived from and proportional to it in proximity to those parts of the disc
in which induced currents are being generated in such a way that the two sets of
currents react the one on the other. The conductor carrying the current to be
measured is preferably wound in such a manner as to lie in part under the poles of
the shunt magnet.
To the disc of the motor or to another disc on the same spindle I apply a
permanent magnet which by the currents it induces in the rotating disc_constitutes
an electric brake as described in my before mentioned Specifications. In order to
indicate the rotations of the disc I employ counting mechanism of the ordinary
kind.
Figure 1 of the accompanying drawing represents in side elevation Figure 2 in
plan and Figure 3 in front elevation a meter constructed according to my invention
for measuring alternating or intermittent electrical currents. Figure 4 represents a
modification of the meter represented in Figures 1, 2 and 3.
The same letters of reference indicate the same parts in Figures 1, 2 and 3.
a is the disc or armature (made preferably of aluminium) by the rate of rotation
of which the strength of the current to be measured is indicated; a worm b on the
spindle c of the disc a transmits motion to the counting or indicating mechanism
at d (see Figure 2). As this counting or indicating mechanism constitutes no part
of my invention I do not consider it necessary to represent it in detail; e is an
electro magnet the core of which consists of a series of plates of sheet iron excited
by a coil connected across the mains or a shunt on the mains. f is the
conducting wire of the shunted current which wire is coiled around the core of the
electro magnet e. One part of the disc a is situated between the poles of the electro
magnet e and in a practically constant field. The part of the disc opposite to that
between the poles of the electro magnet e is situated between the poles of a permanent
steel magnet g that is in a constant magnetic field.
The current to be measured enters and passes out of the meter by the con-
nections hi the said current circulating through the four vertical flat coils k k k¹ k
fixed partially between the poles of the electro magnet e and on either side. of
the disc a in the manner which will be understood by reference to the drawing..
The current to. be metered in passing through the meter is divided as will be
understood by an examination of Figures 1 and 2 one part of the current circulating

page_text: through the two upper flat coils k k and the other part circulating through the two
lower flat coils k¹k. The current however need not be divided as represented as
the said current may be passed through the four coils kkkk¹ in series instead of
being divided and each part circulating through a pair only of the said coils. When
the current to be measured is passed through the meter by connections at h² 2 the
disc a is made to rotate at a rate directly proportional to the strength of the
current.
Figure 4 illustrates an arrangement of my invention in which a movable screen
made preferably of copper employed.
a is the disc c the spindle e is a horse shoe laminated iron core which is magnetised
by the current passing through the wire hi; r is the movable screen or mass of
iron carried on a lever pivoted at y; the other end of the lever carries a laminated
iron core w.
The current to be measured enters the wire hi at hand leaves it at i
circulating through the coils t and u; s is a light spring which is extended as the
current through the coil t increases the core w being drawn further into the coil t
and the screen more and more withdrawn from between the poles of the
electro magnet e.
A. permanent magnet is applied to the disc a as in Figures 1, 2
and 3. The magnet e may be excited by a shunt current in which case the direction
of movement of the screen by the current to be measured is reversed. The shape
size and position of the screen may be adjusted by trial for each meter so as to
cause the rate of rotation of the disc to be proportional to the current over
long ranges.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that I claim as
my invention of "Improvements in electricity meters for alternating or interrupted
currents
:-
First-In meters for alternating or intermittent currents in which the rotation
of a disc or other solid of revolution is produced by the reaction of currents induced
in the said disc the juxtaposition of a coil or coils carrying the current to be
measured or a current proportional to it and a coil or coils constituting a shunt
circuit in such a way that the field or fields produced by the series coils lies or lie
partly under the poles of the shunt magnet substantially as and for the purpose set
forth and illustrated by Figures 1. 2. and 3 of the accompanying drawing.
Secondly-In meters for alternating or intermittent currents in which the
rotation of a disc or other solid of revolution is produced by the reaction of currents
induced in the said disc or by the distortion of a field producing such currents the
regulation of the driving force by the movement of a screen or of a mass of iron
in the magnetic field in the manner and for the purpose set forth and illustrated in
Figure 4 of the accompanying drawing.
Dated this 10th day of June 1901
W. T. WHITEMAN,
Agent for the Applicant.