AN ELECTRIC METER
Year: 1884

page_text: COMPLETE SPECIFICATION.
I, ALEXANDER PELHAM TROTTER, of No 7 Furnivals Inn, in the County of
Middlesex, Engineer, do hereby declare the nature of my invention for "AN
ELECTRIC METER" 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 apparatus for measuring the electricity passed through
a circuit in a given time. In this apparatus, clockwork causes a slotted lever to
reciprocate. The pin of a connecting rod nearly at right angles to the lever, is
drawn along the slot of the lever nearer to its fulcrum by a spring and is drawn
farther from the fulcrum by the core of a solenoid through the coil of which passes
the current that is to be measured or a known fraction thereof. The connecting
rod works, by means of a pawl and ratchet, or silent foed, the gear of a counter,
giving greater movement thereto at each stroke of the lever the farther its pin is
drawn from the fulcrum by the attraction of the solenoid in opposition to the
spring.
In order to dispense with attendance for winding up the clockwork, I effect this
by automatic electric remontoir apparatus of the following kind. On the spindle
of the barrel moved by the weight or spring of the clock I fix a lever from which
is suspended the core of a solenoid, and on the lever I mount a tumbling weight
which works a contact. When the spindle of the barrel has turned to a certain
extent, moving the clockwork, the lever is raised to such an attitude that the
tumbling weight falls over, making contact, whereby an electrical current is.passed
through the coil of the solenoid. This current, exciting the solenoid, causes it to
attract its core, drawing back the lever and so winding partly up the clock barrel,
and the lever having been thus drawn back, its tumbling weight falls over breaking
contact for the solenoid.
The accompanying drawing is a front view of the apparatus, the front of the case
being removed to shew the mechanism behind A is a disc fixed on the arbor of the
minute band of the clock, and having a number of equidistant studs projecting
from it, so that as A revolves, these studs act successively at equal intervals on the
curved inclines b of a lever B which is suspended from a fulcrum C. In the lever B
there is a slot extending a certain distance from its fulcrum, and having engaged in
it the pin H of a connecting rod K. The pin H is also engaged in the slot of an
arm projecting from a vertically sliding rod L that is attached to the core M of a

page_text: solenoid N. This solenoid has its coil connected in the circuit conductors D E or
in a branch of the circuit, the current through which is to be measured. The
core M is urged upwards by a counterweight or adjustable spring, not shewn.
The connecting rod K. works pawls acting on a finely toothed ratchet wheel O
geared with a counter P. The greater the attractive power of the solenoid N on
its core M, the farther is the pin H moved from the fulcrum C of the lever B, and
consequently the greater is the movement given to the pawls k, and to tho
counter P. A scale X serves to indicate the attractive force acting on M. In the
remontoir apparatus, R is the spindle of the weight or spring barrel, on which is
fixed the lever S connected to the core t of a solenoid T. On the lever S is
mounted the tumbling weight U on an arm V, which can oscillate freely between
adjustable screw stops. When the lever is in the position shewn, the tail v makes
electrical contact with a spring, causing an electrical current to be transmitted from
a shunt D'E' of the main circuit through the coil T which attracts its core t
downwards, moving the lever S and so turning partly round the spindle R and
thereby partly winding up the clock work. When the lever S has thus been moved
a certain distance, the weight U tumbles over to the right breaking contact at v.
The movement of the clock may be regulated by a balance or pendulum. When
a pendulum is employed, I prefer to apply to it a known arrangement for calling
attention to an accidental stoppage or for interrupting the current when a stoppage
occurs. 1 hang by a wire from the pendulum a light vane over a little mercury
contained in a vessel below.. While the pendulum swings, this vane is deflected by
the resistance of the air that so as not to touch the mercury, but when the pendulum
stops, the vane langs vertically down so as to touch the mercury making an
electrical contact by which a bell may be rung to give notice of the stoppage,
or by which a switch may be worked to open the main circuit or to introduce
a considerable resistance.
Having now particularly described and ascertained the nature of my i invention,
and in what manner the same is to be performed, I declare that what I claim is.:-
1. The construction of electric meter, wherein a lever, caused to oscillate by
clockwork, moves a counter by a connecting rod which is made to act at a greater
or less distance from the fulcrum of the oscillating lever by the greater or less
attraction of a solenoid having its coil in the circuit to which the meter is applied,
substantially as described.
2. In an electric meter of the kind referred to in the preceding claim, the use of
electric remontoir apparatus constructed and operating substantially as described.
Dated this 15th day of November 1884
ABEL & IMRAY,
Agents for the Applicant,
28, Southampton Buildings, 40
London, W.C.