An Improved Apparatus for the Measurement of Electrical Energy.
Year: 1890

page_text: Date of Application, 5th Aug., 1890-Accepted, 29th Nov., 1890
COMPLETE SPECIFICATION.
[Communicated from abroad by EDWARD WESTON, of Newark, New Jersey, United
States of America, Electrician.]
An Improved Apparatus for the Measurement of Electrical Energy.
I, HENRY HARRIS LAKE of the firm of Haseltine, Lake & Co. Patent Agents,
45 Southampton Buildings in the County of Middlesex 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 :-
The invention consists in an electrical measuring instrument intended chiefly for
use as an electrodynamometer for the measurement of alternating currents of
electricity. The instrument embodies a fixed or stationary coil in the field of force of
which is pivoted a vibrating coil, the said coils being electrically connected. The
movable coil on the passage of a current through the circuit including both coils,
assumes an angular position, depending upon the difference of potential between the
terminals of the circuit, and the extent of angular displacement of the movable coil' is
shown by an index or pointer on a suitable scale.
In the accompanying drawings, Fig. 1 is a plan view, Fig. 2 a section on the
line XX of Fig. 1, and Fig. 3 a section on the line Y Y, Fig. 2. Similar letters and
numbers of reference indicate like parts.
1 is the base of the instrument suitably recessed to receive the two bobbins or
spools, 2 and 3, which are placed end to end, and surrounded by coils of fine, insulated
wire connected in series. The bodies of the spools 2 and 3 are made of rubber or
other insulating material, and they are hollowed out to form a spherical cavity, 4,
Fig. 3. 5 is a circular frame of insulating material, such as shellacked paper, on
which is wound a coil of fine wire, the terminals of which are connected to the pivot
pins 6 and 7, which pins are secured to said frame. The said pins are therefore
journaled in the bodies of the spools 2 and 3, and have their bearings in adjustable
steps 8 and 9, which are supported upon the metal arms 10 and 11. The arms 10
and 11 are secured to an outer cover 12, which extends over the outer face of the
spool 2, by means of screws 13. Surrounding the pivot pins 6 and 7 are spiral
springs 14 and 15, the inner ends of said springs being connected to said pivot pins,
and the outer ends of said springs being connected to arms 16 and 17,-which are
pivoted at the extremities of said arms 10 and 11. By turning the arms 16 and 17 on
their pivots, the springs 14 and 15 may be contracted or expanded. Supported on the
upper pivot pin is a light metallic disk, which carries an indicating needle 18. The
covering plate 19 on the face of spool 3, carries a horizontal plate 20, to which is
secured a scale plate 21. Also to the plate 19 is fastened by screws 22, a cross-piece,
and through this cross-piece extend screws 23, which enter the base 1. By removing
these screws 23 the spools 2 and 3 and associated parts can be separated from the base.
Within the ring 5 and filling the space included in it, is a sheet of mica 24. This
sheet passes through an opening in a diaphragm 25 of rubber or other non-conducting
material, which is held between the spools 2 and 3, and extends diametrically across
the spherical opening or chamber 4. 26 is an ordinary resistance coil, supported in a
recess on the base in any suitable manner. 27 and 28 (dotted lines), are two contact
springs, the spring 28 being in electrical contact with the binding post A.
29 is a
push button passing through a sleeve 30 which surrounds an opening in the base
plate 1, which button, when depressed, moves the springs 27 and 28 into contact, and
so closes the circuit.
The circuit in the instrument proceeds as follows: From the binding post B by
wire a to one of the terminals of the coils on the spools 2 and 3 and through said coils,
the other terminal of which is connected to the lower spring 15, the current then
passes by the pivot. 7 to and through the movable coil on the frame 5, and thence to

page_text: the pivot 6 and upper bracket 10, thence by the wire b through the resistance
coil 26, to the contact plate 27 by wire c, to contact plate 28 and so to binding
post A.
It is intended to use this instrument to measure the electromotive force of
alternating currents; or in other words, as the several coils are all connected in series,
and as the resistance coil 26 is made of high resistance, to measure the difference of
potential between the binding posts A and B. Inasmuch as the movable coil
suspended within the fixed coil on the spools 2 and 3 is connected in circuit with the
latter, it follows that a reversal of the current in one coil will occur simultaneously
with the reversal of the current in the other; and hence the needle will always be
deflected in the same direction, regardless of the alternations of the current. Of
course, the normal or zero position of the frame 5, when no current is passing through
the instrument, is in a plane passing through, the longitudinal axis of the coils on the
spools 2 and 3, as shown in the drawing, Figs. 2 and 3; and the needle is adjusted
so as to mark zero on the scale when the movable coil is in this position.
of
The object of the mica diaphragm 24 is to deaden the vibrations of the coil upon
the frame 5 through its action as a fan; and this effect is increased by the presence
the diaphragm 25, between which and the movable diaphragm 24, the air becomes
somewhat compressed during the movement of the frame, and hence offers still greater
resistance to the motion of the latter.
The presence of the diaphragms 24 and 25, is not, however, essential. So also I
may arrange the instrument so that the movable coil surrounds the fixed coil, and
instead of connecting the movable and fixed coils in series, I may connect them in
multiple arc. In the latter case, I may use a copper strip or other conductor of
low resistance on the fixed spools, and thus adapt the instrument for measuring
strength of current.
Having now fully described and ascertained the nature of the said invention, and
in what manner the same is to be performed, as communicated to me by my foreign
correspondent I declare that what I claim is :-
An electrical measuring instrument, for the measurement of alternating currents of
electricity constructed and arranged substantially as hereinbefore set forth.
Dated this 5th day of Act 1800
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant