IMPROVEMENTS IN RECORDING AND CONTROLLING A SUPPLY OF ELECTRICITY
Year: 1883

page_text: LETTERS PATENT to John Hopkinson, of Westminster Chambers, Westminster,
in the County of Middlesex, F.R.S. for an Invention of "IMPROVEMENTS
IN RECORDING AND CONTROLLING A SUPPLY OF ELECTRICITY"
PROVISIONAL SPECIFICATION left by the said John Hopkinson at the
Office of the Commissioners of Patents on the 13th July 1883.
JOHN HOPKINSON, of Westminster Chambers, Westminster, in the County of
Middlesex, F.R.S., "IMPROVEMENTS IN RECORDING AND CONTROLLING A SUPPLY
OF ELECTRICITY"
My improvements relate to measuring the quantity of electricity which has
passed through a given conductor in any time and to breaking the electric circuit
if the current passing should become too great, or if any part of the circuit should
be in electric connection with the earth.
When an electricity meter is used for measuring the electricity which passes into
an electric accumulator, it is sometimes useful to provide that the meter shall auto-
matically deduct the current which flows back from the accumulator when it is
discharging. This I effect in meters driven by a small dynamo machine by means
of an electro-magnet switch which reverses the connection of the armature when the
direction of the current changes, or by means of a gear like the back gear of a
lathe between the meter proper and the counting mechanism which is thrown in
and out of gear by an electro-magnet when the direction of the current changes.
It is also useful with accumulators to arrange that the meter should give a signal
or disconnect the circuit when the charge in the accumulator reaches a certain
amount; this I effect by the counting mechanism operating an alarum as a clerk
operates an alarum, or by causing the counting mechanism to make an electric
contact which shall sound the alarum or break the circuit. In order to give the
meter described in the Specification of my Letters Patent N° 49 of 1882 a longer
range I make use of two solenoids, one made of thick wire, the other compara-
tively thin, also of an electro-magnetic switch which causes the current to pass
through one or the other according to its amount, and at the same time to actuate
Price 671

page_text: a back gear similar to that already referred to excepting that it does not reverse
the direction of rotation,
"
When meters are used for measuring the supply to a consumer, it is important
that such consumer shall be disconnected if he takes too much current or if he has
an "earth on bis circuits. To effect this I have a tumbling piece in a position
approaching unstable equilibrium, so that when released it sharply jerks out of
connection a contact breaker. This tumbling piece is held by a trigger piece,
which is pulled back by an electro-magnet, or in some cases, by one or other of
two electro-magnets. The electro-magnet may be wound in the usual way, in
which case it does not specially release by an earth contact; or it may be wound
with two coils in opposite directions, in which case it releases, if there is a small
current to earth in one coil, or if there is a large current in the two coils. This
"cut-out" may be used with advantage for safety, without a meter. The contact
breaker may be mercurial, and the tumbling piece may be moved, when released,
either by gravity, or by a spring.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Hopkinson in the Patent Office on the 12th January 1884.
JOHN HOPKINSON of Westminster Chambers Westminster in the County of
Middlesex F.R.S. "IMPROVEMENTS IN RECORDING AND CONTROLLING A SUPPLY
OF ELECTRICITY
"
My Improvements relate to recording the quantity of electricity which has
passed through a given conductor in any time and to breaking the electric circuit
if the current passing should become too great or if any part of the circuit should
be in electric connection with the earth.
When an electricity meter is used for measuring the electricity which passes into
an electric accumulator it is sometimes useful to provide that the meter shall
automatically deduct the current which flows back from the accumulator when it
is discharging This I effect in metres driven by a small dynamo machine by
means of an electro magnetic switch which reverses the connection of the armature
when the direction of the current changes or by means of gear like the back gear
of a lathe which is situated between the meter proper and the counting mechanism
and which is thrown in and out of gear by an electro magnet when the direction
of the current changes It is also useful with accumulators to arrange that the
meter shall give a signal or disconnect the circuit when the charge in the accumu
lator reaches a certain amount. This I effect by the counting mechanism operating
an alarum as a clock operates an alarum or by causing the counting mechanism to
make an electric contact which shall sound the alarum or break the circuit. In
order to give meters (such for example as are described in the Specification of my
Letters Patent N° 49 of One thousand eight hundred and eighty two) a longer
range I make use of two solenoids one made of thick wire the other of compara-
tively thin wire also of an electro magnetic switch which causes the current to
pass through one or the other according to its amount and at the same time to
actuate a back gear similar to that already referred to excepting that it does not
reverse the direction of rotation.
When meters are used for measuring the supply to a consumer it is important
that such consumer shall be disconnected if he takes too much current or he has
an "earth"
on bis circuits. To effect this I have a tumbling piece in a position
approaching unstable equilibrium so that when released it sharply jerks out of
connection a contact piece. This tumbling piece is held by a trigger piece which
is pulled back by an electro magnet or in some cases by one or other of two electro
magnets. The electro magnet may be wound in the usual way in which case it
does not specially release by an earth contact, or it may be wound with two coils
in opposite directions in which case it releases if there is a small current to earth
in one coil or if there is a large current in the two coils This "cut-out" may be
used with advantage for safety without a meter. The contact breaker may be
mercurial and the tumbling piece may be moved when released either by gravity
or by a spring.
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 methods of arranging an electric meter for use with accumulators in such
wise that the dials will run backward when current returns from the accumulator
are shewn diagrammatically in Figures 1. 2. 3 and 4. The arrangement shewn in
Figures 1. and 2 is applicable to meters such as are described in the Specification
of my Patent No. 49 of One thousand, eight hundred. and eighty two and of my

page_text: Patent No 3576 of One thousand eight hundred and eighty two they being driven
by a small dynamo machine and the purpose of my Invention is automatically to
reverse the direction of rotation of the said small dynamo machine when the
direction of the current to be measured is reversed. Figure 1 represents the
electrical connections diagramatically-A A. B B are the main leads conveying
the current to be measured. C is the solenoid or electro magnet of a meter such
as that described in the Specifications of my before mentioned Patents-D E are
connecting terminals indicated by the same letters in Figure 2. F. G H I J. K.
LM are terminals for automatically reversing the direction in which the current
circulates in the arinature N of the small dynamo of which P represents
diagramatically the magnets The terminals F G. H. I. J. K (Figure 2) carry
contact springs which are brought into electrical connection by the pivoted
piece so that contact is made either between F and G and between J and K or
between G and H and between I and J according to the position of the said piece Q
which carries at the extremities of two of its arms pegs R which make contact with
the said springs. One of the arms of the pivotted piece Q carries a coil of fine wire T
which is connected to the terminals L M. A fixed coil of thick wire S is connected
to the terminals D and E and conveys (as does also the solenoid of the meter) the
whole of the current which passes to or from the accumulator and which it is
desired to measure.
The contact breaker of the meter is shewn diagramatically at
V Figure 1. The wires W and X are connected to the two main leads A and B
and have therefore the full difference of potential due to the dynamo or the battery.
The mode of action is as follows. A small current constantly circulates in the
moveable coil T making its iron core if such be used of constant polarity The
direction of the current in the fixed coil will depend on whether the current is
passing to or from the accumulator and on its direction will depend whether the
coil T is sucked into the coil S or repelled from. it and consequently whether
electrical connection is made by the piece Q between the springs G H and I. J or
between the springs F. G and J. K thereby determining the direction of the current
in the armature N-of the small dynamo. Hence, since the direction of, the current
in the magnet P of the small dynamo. is always the same a change of direction of
the current measured will change the direction of rotation of the meter. It is clear
that the details of this arrangement may be varied for example the direction of the
current in the magnet P might be reversed whilst that in the armature N remained
. constant ; the mechanical arrangement of the automatic reverser shewn in Figure 2
is also susceptible of variation within considerable limits without departing from the
nature of my Invention.
+
:
.
The arrangements shewn diagramatically in Figures 3 and 4 are also applicable
to the meters described in the Specification of my before mentioned Patents, but
it may be used with other meters. Referring to Figure 3 A is a shaft driven by
the meter proper. B is a shaft connected with the counting dials. On the shaft A
is a pinion gearing into a wheel D loose upon the shaft B. In one with or
fixed to the wheel D is a bevel wheel E gearing into a second wheel F carried by
a disc G which is loose upon the shaft B. The wheel F gears into a third bevel
wheel H fast upon the shaft B. The wheel D is only frictionally connected with
the disc G by means of a spring or its equivalent I. The disc G may either
revolve together with the wheel D in which case the whole system from D to B
revolves together or it may be stopped by the detent K in which case the wheel D
and shaft B will revolve with equal but opposite angular velocities. The detent K
is operated by an electro magnetic arrangement which is indicated diagramatically
at Land which may take a variety of forms. In that shewn in the diagram it
consists of a thick coil carrying the whole or a determinate portion of the current
to be, measured which attracts or repels either a permanent magnet or an electro
Inaguet excited by a coil of fine wire having its ends connected to the two poles/o
the battery or dynamo machine. Figure 4 shows a modification of the arrange
:inent shewn in Figure 3,in which modification the frictional connection I is replaced
by a method of driving through spur gear. In one piece with or fixed to .the

page_text: wheel D is a spur wheel M gearing into a pinion N on the same spindle with an
equal pinion P The said spindle is carried on a disc Q which is loose on the
shaft B. The pinion P gears into a wheel S which is fast on the shaft B. The
dise Qmay either be free or may be stopped by the detent T The detents K
and T are both operated by the electro magnetic arrangement L in such wise that
when the detent K leaves the disc G free the detent T shall stop the disc Q but
that when the detent K stops the disc G the detent T shall leave the disc Q free
The form of the detent K-and of the electro magnetic arrangement L together
with the mechanical connections between them may be varied as may be convenient.
In figure 4 the parts which correspond with those described with, reference to
Figure 3 are marked with the same letters of reference.
:
Electricity meters may be applied with advantage to accumulators for the purpose
of calling attention or of automatically disconnecting when a specified quantity of
electricity has passed into the accumulator. Figures and 6 show two ways of
accomplishing this-A and B (Figure 5) are discs of insulating material carried on
two of the shafts of the counting mechanism; each carries a metal contact piece
C and D which serve to connect contact springs E F and G. H and so complete
the circuit of an electric bell K. Where precision is not required a single contact
may be used the setting of the discs A and B can be accomplished in the same
way as in an ordinary alarum. Figure 6 shows a modification in which a bell
operated by a weight is used instead of an electric bell-A is a cam carried on one
of the shafts of the counting apparatus. This cam releases a lever B which in its
.turn disengages from a pin C on the drum D and permits a weight E to descend
It is clear that the arrangements shewn in Figures 5 and 6 may. be used to
actuate some signal other than a bell or to disconnect the accumulator from the
dynamo.
By using two coils one of thick wire and the other of thin wire in an electricity
meter the range of such meter may be vastly increased. When the current is
large it must circulate either entirely or principally in the thick coil; when the
current is small it must be entirely or principally operative in the thin coil.
Figures 8 and 10 show an electro magnetic arrangement for effecting the change.
The current passes through the thick coil shown diagramatically at A and then
through the thin coil B unless this is short circuited by the contact piece C (shown
as dipping into mercury cups) The current passes from B. to the solenoid D in
which is an iron core E suspended from one arm of the unstable balance F from
the other arm of which hangs the contact maker C. It will be seen that when the
current is great the piece C will dip into the mercury; when it is small it will be
lifted out of it. The balance F also actuates the detent G (Figure 7) or the
detents G and J (Figure 9) In Figure 7 is shown' a change speed gear which
enables a thick coil and a thin coil to indicate on the dials by the same scale. A
is-a shaft driven by the meter proper. B the first dial shaft C is a pinion on A
gearing into the spur wheel D loose on the shaft B. E is a pinion in one piece
with or connected to the wheel D and gearing into a wheel F which is carried on
the same spindle with the pinion I. The pinions F and I are carried on a spindle
mounted on a disc H loose upon the shaft B. The pinion I gears with the
.wheel K fixed upon the shaft B; there is a frictional connection L between the
wheel D and the disc H. If the disc H be held fixed by the detent G the shaft B
will revolve slower than the wheel D in any desired proportion, the relative
diameters of the wheels E FI K being suitably arranged. If the detent G release
the disc H the whole system from D to B will revolve together... Figure 9 shows.&
modification in which the frictional connection L is dispensed with in exactly the
same way as hereinbefore explained with reference to Figure 4 and its mode of
action will be clearly understood from the description of that Figure. Figure 11
shows a modification of the mode of connecting the thick and thin coil.
represents the thick coil and B the thin coil of the meter but the said coils are
arranged in divided circuit instead of in series and the contact piece C makes or
breaks the circuit of the coil A instead of short circuiting the coil B. It is obvious
A

page_text: that the arrangements shewn in Figures 7 to 11 may be applied to many forms of
meter but in Figure 12 I shew one way of arranging the coils in a meter
constructed according to the Specifications of my before mentioned Patents N° 49 of
One thousand eight hundred and eighty two and N° 3576 of One thousand eight
hundred and eighty two. It will be observed that two coils A and B (one of thick
wire and the other of thin wire) are fixed one above the other and that the
governor C has suspended from it two moveable armatures D and E This
application of my Invention will be readily understood from the description herein-
before given with reference to the diagrams in conjunction with the explanation of
'my meter
as given in the Specifications of my said prior Patents-The
arrangements of the coils of the solenoids may be varied to attain the same end
for example a number of equal coils may be used and these may be automatically
connected in series for small currents and in parallel circuit for large currents.
Figures 13, 14, 15 and 16 shew diagramatically automatic cut-outs arranged
according to my Invention the said cut-outs consisting of an electro magnet A. a
tumbling piece B placed in a position at or near that of unstable equilibrium and
a contact breaker C. The said electro magnet A attracts an armature D and when
'the strength of the magnet exceeds a certain amount draws it down and releases
the detent E (Figure 13) so that the tumbling piece B turns over with rapidly
accelerating velocity and jerks out the contact breaker C which should be connected
to the tumbling piece B by a somewhat slack string or thread F. Figure 14 shews
a convenient modification of the arrangement wherein when the armature D is
attracted the tumbling piece B is acted upon by the til end of the said
armature D. In the arrangements of cut out shewn in Figures 13 and 14 the
form of the electro magnet A may be greatly varied and the weight G upon the
tumbling piece B may be replaced by a spring provided always that the tumbling
piece B is in a position of or approaching one of unstable equilibrium. Figures 15
and 16 shew diagramatically the method of winding a solenoid or electro magnet
to operate a cut out when there is an earth connection on either of the two
conductors. The current on entering the house or other place passes round the
electro magnet and on returning passes round it an equal number of times in an
opposite direction When the currents entering and returning from the house or
other place are equal the electro magnet will be inoperative but if they are
unequal owing to any considerable leakage to earth the action of one coil will
preponderate above that of the other and will actuate the cut out. By winding
the entering and returning coils upon the two limbs of a horse-shoe magnet it is
possible to make the saine magnet operate the cut out either when the current is
excessive or when there is a smaller current passing to earth for when the current
is excessive the horse shoe will really act as two bar magnets of like polarity and
therefore be difficult to excité. On the other band when there is a small current
passing in one of the coils to earth it will easily excite the electro magnet as a
horse shoe magnet.
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the same. is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is:-
First In an electricity meter driven by a dynamo electric machine, reversing
the direction of rotation of the dynamo machine by means of an automatic electro
magnetic reverser, whenever the current to be measured is reversed, substantially
as herein described with reference to the illustrative diagrams Figures 1 and 2.
Second-In an electricity meter the combination of reversing gear between the
imeter and the dials, and an electro magnetic arrangement, substantially as
herein before described with reference to Figures 3 and 4.
Third The arrangements herein before described and illustrated in Figures 5
and 6 for operating a signal or breaking a circuit when a certain quantity of
electricity has passed, as applied to a mechanically working electricity meter:

page_text: Fourth In an electro magnetic electricity meter the use of more than one coil for
obtaining a long range, in combination with an automatic switch for varying the
connections of the said coils, and an automatically operated change speed gear
between the meter proper and the dial gear, substantially as herein described and
diagramatically illustrated by Figures 7. 8, 9, 10. 11 and 12.
Fifth In an electro magnetic cut out the use of the piece B, that is to say, a piece
in a position of, or approaching to a position of, unstable equilibrium, to operate
the cut-out when the said piece is released or slightly displaced by the electro
magnet, substantially as herein deseribed and illustrated by figures 13 and 14.
Sixth. In an electro-magnetic cut-out the use in the electro magnet of two opposing-
coils, one for the entering and one for the returning current, for the purpose of
operating the cut out when there is leakage to earth, substantially as herein
described and diagrammatically illustrated by Figures 15 and 16 of the
accompanying drawings.
•
In witness whereof I the said John Hopkinson have to this my Specification set
my hand and seal the ninth day of January One thousand eight hundred and
eighty four