IMPROVEMENTS IN ELECTRIC CURRENT METERS
Year: 1885

page_text: 1, JOSEPH WILSON SWAN of Lauriston, Bromley in the County of Kent,
Gentleman do hereby declare the nature of said Invention for " IMPROVEMENTS
IN ELECTRIC CURRENT METERS" to be as follows:-
My Invention relates to improved apparatus for registering the quantity of an
electric current passed through a circuit during a certain length of time. The
apparatus consists of a clock, a galvanometer and a train of registering wheels;
these three parts are so connected together that if a current is passing in the circuit
with which the meter is coupled, a periodic locking together takes place of the
index wheel of the galvanometer one of the clock wheels and one of the train of
registering wheels. This interlocking is maintained during a length of time
varying directly with the strength of the current passing at the instant the locking
action took place and is terminated when the index wheel of the galvanometer
which is carried round by the clock train, arrives at its zero position. Whereupon
an electrical contact is made which closes an auxilary circuit and causes an electro
magnet to effect the unlocking, and the movement of the registering wheels
therefore ceases until the next period of locking occurs.
A clock moved by weights or springs may be employed as the time recording
part of the apparatus but I prefer to employ an electric clock because of the facility
which it gives for long continued working without frequent attention being
required to keep it going. I also prefer that besides the ordinary wheels and
indices for marking the hours and minutes there should be additional wheels and
a dial to register the days up to 100.
The Galvanometer consists of a solenoid of very thick wire, with a core of soft
iron freely suspended within it by means of a spiral spring, the core having also
attached to it one end of a chain which is attached at its other end to a barrel or
wheel on the index axle. The interlocking takes place between this barrel or
wheel and two adjacent wheels on the same axle, the one connected with the
clock train and the other with the train of register wheels.
The chain which connects the core of the solenoid with the index axle is kept in
tension by a hair spring. When a current passes in the solenoid the core is drawn
down against the pull of the spiral spring which holds it in suspension and with it

page_text: the chain thus turning the index wheel of the galvanometer through an arc which
is in direct proportion to the strength of the current.
The action of locking and unlocking is effected by means of a pair of electro
magnets on opposite sides of a pivoted armature which moves towards one of the
electro magnets when its circuit is momentarily closed by the action of the clock.
The momentary closing of the circuit which effects the locking of the wheels occurs
invariably at regular intervals, preferably once in every hour and is followed after
a variable interval by the action of the opposite electro magnet which effects the
unlocking. The duration of the interval between locking and unlocking is
determined by the extent of the are through which the index. wheel of the
galvanometer was moved from its zero by the action of the current on the core at
the instant of locking as before explained.

page_text: I JOSEPH WILSON SWAN of Laureston Bromley in the County of Kent Gentleman
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 improved apparatus for registering the quantity of an
electric current passed through a circuit during a certain length of time. The.
apparatus consists of a clock or Galvanometer and a train of registering wheels.
These three parts are so connected together that if a current be passing in the
circuit with which the meter is coupled a periodic locking together takes place of
the index wheel of the Galvanometer one of the clock wheels and one of the train
of registering wheels This interlocking is maintained during a length of time
varying directly with the strength of the current passing at the instant the
locking action took place and is terminated when the index wheel of the galvanometer
which is carried round by the clock train arrives at its zero position, whereupon an
electrical contact is made which closes an auxiliary circuit and causes an electro-
magnet to effect the unlocking, and the movement of the registering wheels therefore
ceases until the next period of locking occurs.
A clock moved by weights or springs may he employed as the time recording
part of the apparatus but I prefer to employ an electric clock because of the
facility which it gives for long continued working without frequent attention being
required to keep it going I also prefer that besides the ordinary wheels and
indices for marking the hours and minutes there should be additional wheels and
a dial to register the days up to 100.
The galvanometer consists of a solenoid of very thick wire with a core of soft iron
freely suspended within it by means of a spiral spring the core having also attached
to it one end of a chain which is attached at its other end to a barrel or wheel on
the index axle The interlocking takes place between this barrel or wheel and two
adjacent wheels on the same axle the one connected with the clock train and the
other with the train of register wheels.
The chain which connects the core of the solenoid with the index axle is kept
in tension by a spring. When a current passes in the solenoid the core is drawn
down against the pull of the spiral spring which holds it in suspension and with
it the chain thus turning the index wheel of the galvanometer through an arc
which is in direct proportion to the strength of the current.
The action of locking and unlocking is effected by means of a pair of electro
magnets on opposite sides of a pivoted armature which moves towards one of the
electro magnets when its circuit is momentarily closed by the action of the clock.
The momentary closing of the circuit which effects the locking of the wheels occurs
invariably at regular intervals preferably once every hour and is followed after a
variable interval by the action of the opposite electro magnet which effects the
unlocking The duration of the interval between locking and unlocking is deter-
mined by the extent of the arc through which the index wheel of the galvanometer:

page_text: was moved from its zero by the action of the current on the core at the instant of
locking as before explained.
And in order that my said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the annexed sheet of drawings the same letters of reference
indicating corresponding parts in all the figures.
Figure 1 of my drawings is a front elevation and Figure 2 a side elevation of
an apparatus constructed according to my Invention. A is an electric clock
Ba
galvanometer and Ca train of gearing in connection with an index or counter D.
The galvanometer consists of a solenoid of thick wire E within which is suspended
freely from the spring F a soft iron core G having attached to it one end of a
chain H which passes over or round and is attached by its opposite end to a barrel
or wheel I fast on the axle K of the galvanometer needle E another chain M being
attached to and passing over another wheel N of less diameter than the wheel I
the opposite end of the said chain being attached to a spring O. The spring F in
its normal condition maintains the core G in its normal position and the needle L
at zero when no current is passing through the solenoid When however a current
is passing through the solenoid the core G will descend or be drawn down against
the pull of the spring F and through the chain H rotate the axle K causing the
needle to be deflected from zero more or less according to the strength of the
current. On the axle K of the galvanometer needle are mounted loosely two toothed
wheels P and Q the wheel P being in gear with the train of wheels C and the
wheel Qin gear with the clock work. Between these wheels and also between
the wheel P and the barrel I are springs R which when compressed as hereinafter
described cause the said wheels P and Q to be locked and rotate with the barrel I.
The periodical interlocking and unlocking herein before referred to are caused
to take place by preference once every hour and is effected by means of a pair of
electro magnets S. S¹ arranged on opposite sides of an armature T which is pivotted
at U and connected at its lower end to the axle K of the galvanometer needle.
These magnets are energized by an auxiliary circuit the current from which is
caused to pass through the magnet S for affecting the interlocking at the appointed
times by any suitable part of the clock work actuating a suitable contact maker or
switch, the unlocking being effected by switching the current from the magnet S
to the magnet S₁ by the galvanometer needle when at zero acting on suitable
mechanism for the purpose When the magnet S is energised the armature T is
attracted thereby, and caused to turn on the pivot U and as the lower end of the
armature is connected to the axle K the said axle will be moved longitudinally
forcing the wheels P and Q and the barrel I closer together and compressing the
springs R between them thereby creating sufficient friction between the said wheels
and barrel to cause them to rotate together by the clock mechanism.
This unlocking is maintained until the galvanometer needle is carried round to
its zero position by the clock work rotating the wheel Q during which time the
counting mechanism is rotated through the train of gearing C thereby indicating
on the dials of the counter the amount of.deflection imparted to the needle L.
When the needle is returned to its zero position the auxiliary current is shunted
by suitable switch mechanism to the magnet S¹ thereby causing the armature T to
be attracted in the opposite direction thus affecting the unlocking by moving the
axle K longitudinally so as to separate the wheels P and Q from the barrel I,
the wheel being then free to rotate independently of the barrel I and the wheel P
and the train of wheels C ceasing to operate the counting mechanism until the
locking at the next period takes place.
.
It will thus be seen that the deflections of the galvanometer needle and conse-
quently the strength of the currents passing through the circuit to which the meter
is attached will be periodically registered on the dials of the counter D.
In addition to the ordinary clock mechanism and dial for indicating hours and
minutes an additional dial and wheels are provided as at W for registering days
say up to 100,

page_text: 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 electric current meters the combination of a clock, a galvanometer and
registering wheels, connected and operating together substantially as hereinbefore
described so that under the influence of the current to be measured a periodical
engagement of the operating parts takes place and is maintained for a length of
time varying with the strength of the current when the said engagement takes
place substantially as hereinbefore described with reference to the accompanying
drawings.
Second. The general arrangement and combination of parts constituting the
electric current meter substantially as hereinbefore described and illustrated in
the accompanying drawings.