Improvements in Meters for Recording the Consumption of Electrical Energy Supplied at Differential Rates.
Year: 1894

page_text: Date of Application, 28rd July, 1894
Complete Specification Left, 22nd Apr., 1895-Accepted, 23rd July. 1895
PROVISIONAL SPECIFICATION.
Improvements in Meters for Recording the Consumption of
Electrical Energy Supplied at Differential Rates.
We, ALFRED GEORGE COOPER, of 43, George Lane, Lewisham, Kent,
Electrician, and THE BRITISH THOMSON-HOUSTON, LIMITED, of 38, Parliament
Street, in the City of Westminster, Electrical Engineers, do hereby declare the
nature of this invention to be as follows:-
To use a divided or separate winding in the meter to register currents which are
charged at different rates, so as to do away with a second meter, where lighting for
instance & power are charged at different rates.
The whole being registered on one dial & no connections will be necessary as
they will be performed by the meter.
Improvements in Meters for Recording the Consumption of
Electrical Energy Supplied at Differential Rates.
We, ALFRED GEORGE COOPER, of "Fair Home," Bexley Heath, in the
County of Kent, Electrician, and THE BRITISH THOMSON-HOUSTON, LIMITED,
of 38, Parliament Street, in the City of Westminster, Electrical Engineers, 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:—
This invention relates to means adapted for use in recording the supply of
electrical energy when applied to lighting, motive power and other services, and
charged to the consumer at different rates; the object of the invention being to
enable the consumption for such various uses and at such differential rates to be
recorded on a single instrument.
In order to encourage consumers of electricity to use it for motive power and
heating purposes, it is a common practice to supply current for such uses at a lower
rate, usually half that charged for lighting. This necessitates the employment of
two meters, one for measuring the current used in lighting, and the other for
measuring that applied to other services.
In order that our invention and the mode of carrying the same into effect may be
readily understood, we will proceed to describe the same with reference to the
accompanying illustrative diagrams; it being presumed that the current employed
for lighting is to be charged at double the rate charged for current supplied for
motive power and other purposes. In diagram Fig. 1, D represents the dynamo or

page_text: other source of electrical energy. M M' are the main leads. E is the meter for
lighting and E' the meter for motive power and other purposes; these being
respectively provided with main bobbins S S', wound in series with their respective
circuits, and with armatures a s¹ arranged as shunt circuits. 13³ aro lamps and
P an electric-motor.
In the Thomson-Watt meter, as in many others, a bobbin wound in series carries
the main current and acts inductively on an armature arranged on a shunt circuit.
Assuming that the main bobbin has twenty series turns producing a magnetic field
calculated to cause the armature to register 10,000 watts per hour or 10 Board of
Trade units, when 100 ampères are passing through the meter, and that the rate
chargeable is 8d. per B.T. unit, the consumption indicated on the register will be
equivalent to 6s. 8d. If these 10 B.T. units had been applied to motive power or
other purposes (for which 4d. per unit is to be charged), to admit of the consumption
being registered on the same meter, it would be necessary to cause only 5 units to
be registered in order that the charge may be assessed at 3s. 4d. or half that
applicable to current employed for lighting purposes.
With this object, we may employ a separate winding contained in the same meter
for the power circuit, as illustrated in diagram Fig. 2. D represents the dynamo,
M M the main leads, S S' the bobbins pertaining to the lighting and power
circuits respectively, and s the armature, common to both those circuits, arranged
as a shunt.
The bobbin S¹ has half as many turns as are comprised in the bobbin S,
so that a current flowing through the bobbin S₁ produces half as much effect on
the meter-armature and consequently on the indicator, as a current of equal
intensity flowing through the bobbin S. An arrangement of an equivalent
character is illustrated in diagram Fig. 3, where the current flowing through the
motor traverses only one half the turns in the main winding.
Should it be desired to charge differential rates proportioned otherwise than in
the ratio of 2 to 1, the number of turns allotted to the respective circuits must be
apportioned accordingly.
In a similar manner, charges at three or more different rates may be provided
for and indicated by means of a single meter, the currents of lower selling value
being led through a reduced number of turns of the main bobbin proportionate in
each case to the rate chargeable.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we claim :-
1. The improved means applicable for use in measuring, and recording upon a
single meter-indicator, electric currents or electric energy applied to different
services and chargeable to the consumer at differential rates, substantially as herein
described.
2. In apparatus for measuring, and recording upon a single meter-indicator,
electric currents supplied at differential rates, causing the current or currents to be
supplied at a reduced rate or rates to traverse a number of turns of the main
winding of the meter, reduced in proportion to the rate or rates chargeable.
Dated the 20th day of April 1895.