Improvements in Electric Meters.
Year: 1893

page_text: Date of Application, 5th Dec., 1893
Complete Specification Left, 8th Aug., 1894-Accepted, 22nd Sept., 1894
Improvements in Electric Meters.
HENRY CAPEL LOFFT HOLDEN Major, Royal Artillery Royal Arsenal
Woolwich S.E. do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in electric meters, whereby they are
rendered more compact in form more accurate in their indications, and more
convenient in use.
My invention further relates to instruments, which depend for their principle of
working, on the extension or increase of length which takes place in a wire or
wires through which an electric current is passing, whereby they are heated; the
extent of the extension thus produced being proportional to the heat.
In my instrument the working wire is wound round and round two pulleys
supported on a frame with arms at each end of it.
The pulleys are a short distance apart, generally not more than nine inches, but
I do not in any way confine myself to this length, which may be greater or less
according to the particular circumstances of the case.
According as the instrument is to be used as an ampère meter or a voltmeter the
pulleys are made of conducting or non-conducting material.
The two ends of the wire or wires wound round the pulleys as above described
are fixed to separate and insulated supports, which supports are intended to be in
connection with the source of electrical supply.
The two pulleys above described are free to move around their axis pins.
An arbor carrying a lever arm, weighted or strained by a spring, and also
carrying a pointer for the purpose of indicating its position, is situate either above
or below the centre of the lower, or it may be in some cases the upper, set of wires,
and keeps these wires in tension by means of a small roller which is attached to
the lever by a connecting link, which same roller bears on the wires.
When the wires are heated by the current and extend, the roller and lever
connected with it move, under the influence of the weight or spring, and take up
the sag produced by the extension of the wires, while the pointer fixed to the
arbor carrying the lever and roller moves also, and indicates by the extent of its
movement the strength of the current passing.
The sag in this case is that due not only to the extension of the set of wires on
which the roller bears on one side of the pulley, but in addition to this to the
extension of those on the other side of the pulley. A far greater angular movement
is thus communicated to the arbor through the lever arm and so to the pointer than
would be the case if this combination of pulleys and wires, arranged as above
described, were not adopted.
Compensation for temperature is obtained by means of a wire of the same
material as the working wire or one having the same coefficient of expansion.
This compensating wire is attached to the two arms of the frame carrying the
pulleys, one arm being hinged and arranged so that the length of the working
wire between its pulleys increases or decreases at the same time and to the same
extent as the compensating wire.
The instrument can also be made self-registering or recording by allowing the
pointer to travel over a moving surface at right angles or nearly so to the direction
of movement of the latter, at the same time providing the pointer with a means
of marking the moving surface either with pen pencil or analogous contrivance.
Dated this Fourth day of December 1893.

page_text: Improvements in Electric Meters.
1 HENRY CAPEL LOFFT HOLDEN Major, Royal Artillery Royal Arsenal
Woolwich 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 that class of electric meters which depend for their
principle of working on the extension or increase in length which takes place in a
wire or wires through which an electric current is passing, which current heats and
raises the temperature of the aforesaid wire or wires; the amount of such extension
being proportional to the temperature to which the wire or wires in the circuit are
raised.
My invention is applicable both to ammeters and voltmeters by suitably
arranging the wires or returns of wire as hereinafter described.
Referring now to the accompanying drawing for the purpose of more clearly
explaining my invention and the manner in which it may be carried into effect.
The working wire V is wound round and round the pulleys P P, supported on
the frame E with arms, A A, at each end of it.
One of the arms A. is hinged at H.
The pulleys P P are a short distance apart generally speaking not more than
nine inches, but the distance may be greater or less according to circumstances.
The pulleys P. P are free to move around their arbors, and may themselves be
made of either nonconducting or conducting material according to whether the
instrument is required to be of high resistance or low resistance or to be employed
as a voltmeter or as an ammeter, they are grooved to retain the wire in position.
The two ends of the wire V are fixed to insulated supports S S. or in some cases it
may be preferable to fix them to the frame itself in which case the frame would be
divided, the one portion being electrically insulated from the other. The insulated
supports S S or the two-portions of the frame, as the case may be, are connected
by one of the usual and well known methods with the source of electrical supply.
An arbor X carries a lever arm C and also a pointer R the object of which is to
render visible the movement of rotation of the said arbor X.
The arbor X also carries a second lever arm to which the weight W, whose
position on the arm is preferably adjustable, is attached; the function of this
weight is to keep a strain on the wire V in all positions of the pointer R; if
preferred, however, this same function may be equally well discharged by a spring
acting in the same manner but instead of the weight.
There is also attached to the arbor X an arm C which is connected to the arbor
of the small grooved roller B by a link. This causes the roller B to bear upon the
lower returns of the wire V.
When the returns of wire are heated by the current and extend this roller B
and the lever C connected with it and the arbor X move under the influence of
the weight or spring and so take up the slack or sag produced by the extension of
the wire V, whilst the arbor X rotates carrying with it the pointer R which latter
moving over a scale indicates the extent of the movement and thereby the current
passing.
The sag in the case of this instrument is that due not only to the extension of
the returns of wire V on which the roller B bears, in this case on the lower side
of the pulleys P P, but in addition to this to the extension of those returns on the
other side, in this case the upper side, of the pulleys P. P., which increases the
effective length of the wire between the pulleys P P under the roller B. Thus a
far greater angular movement is communicated to the arbor X through the lever

page_text: arm to the pointer R than would otherwise be the case if this combination of
pulleys and wire arranged as above described were not adopted.
Compensation for temperature is obtained by means of a wire T. of the same
material as the working wire or else of a material having a similar coefficient of
expansion; this compensating wire T is attached to the two arms A. A of the
frame E in such a manner that the current cannot pass through the wire; one of
the arms A being hinged at H and the wire being kept in a state of strain by the
spring K acting on this arm A and continually tending to force this arm outwards
in such a manner that the length of the working wire V between its pulleys PP
increases or decreases at the same time and to the same extent as the compensating
wire T.
The instrument can also be made self-registering or recording by allowing the
pointer R to travel over a surface of paper or other material moving at right
angles or nearly so to the direction of the movement of the pointer itself, at the
same time providing the pointer with a means of marking the moving surface
either with a pen pencil or analogous contrivance for effecting the same object.
.
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 ;
In electric meters;
The combination of wires, frame, levers pulleys and roller substantially as above
described and for the purpose or purposes set forth.
H. C. L. HOLDEN, Major R.A.