Improvements in Electric Meter Systems.
Year: 1898

page_text: Date of Application, 6th Oct., 1898-Accepted, 6th Dec., 1899
Improvements in Electric Meter Systems.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street.
in the City of London, Electrical Engineers, do hereby declare the nature of
this invention (which has been communicated to us from abroad by Edwin W.
Rice, Jr., residing at Schenectady, County of Schenectady, State of New York,
United States of America, Electrical Engineer) 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 electric meter systems, and particularly to what are
known as 66 demand" or <<
maximum" systems, and consists in certain improve-
ments in the construction and operation of the meter and in other details herein-
after more fully described and claimed.
The cost of supplying energy to a consumer may be divided into two portions,
one corresponding to the amount of plant which it is necessary to provide to
meet the customers' maximum requirements, and called fixed expenses, and
another portion to the amount of coal, oil, etc., required to supply the energy
actually supplied to the customer, and called the operating expenses. It is
obvious that a customer who uses on an average 10 amperes 24 hours per day is
far more profitable to the station than one who uses 240 amperes for one hour
per day. It is therefore considered advisable to record not only the total energy
used by the subscriber during a certain definite period, as, for example, for one
month, but also to record the maximum load which he puts upon the station
during that time.
To this end there provided in each consumers circuit an integrating Watt or
Ampere meter, and also an indicating device of novel construction, for showing
or recording the maximum strength of current used at any time in the consump-
tion circuit.
In the drawings attached to this specification, Fig. 1 is a general view of the
improved maximum meter, while Fig. 2 is a view of a subscriber's system with
its connections to the mains. Referring more particularly to Fig. 1, A, B are
terminals of the instrument, between which terminals is inserted the coil C,
carried in the iron box D) and acting on the core E. This core is suspended
by a link F from the indicating arm G which, in turn, is pivoted at the end
of the fixed arm H, whch is shown as formed in one piece with the cover of the
box D. The arm G carries on its end a stylus pencil or pen J, playing over a
piece of paper or other material K, which is fastened by means of spring
clips L, L and a guide L¹ to the base board M of the instrument. The lever G
is retracted by the spring N which is capable of adjustment by a proper regulation
of the nut N¹.
A dash-pot piston P may be hung by the link P¹ from the point P² on the
lever G.
Referring to Fig. 2, a, b, are the mains of the system. To these mains are
connected the subscribers lines c, d, one of which is shown as including the
current coils e, e of the recording Watt meter Q and also the coil C of the
maximum meter shown in Fig. 1. The armature f of the Watt meter is, as usual,
Price RI

page_text: placed in shunt to the mains through the resistance g. The operation of the
system thus arranged is as follows:-
Current passes through the main a through the current coil e of the Watt-
meter Q, and causes the total amount of energy consumed during the month to
be accurately registered on the dial of the recording Watt meter. At the same
time the passage of this current through the coil C of the maximum instrument
causes the core E to be attracted, and causes the pen or pencil J to trace a line
upon the paper, or other material, which is preferably provided with a scale
marking, as shown. As the load gradually rises the line will become longer
and longer, while, when the current falls to a lower value, the pencil will simply
retrace the path which it has before followed. It results from this, that by an
inspection of the paper K, it is possible to tell what the maximum load on the
mains c, d, has been since the last inspection. The dial h will give the total
energy consumed in the usual way.
The dashpot P serves to prevent an accidental and merely instantaneous short-
circuit, occurring in the subscribers system, from recording an excessive amount
upon the maximum instrument. It will be seen that the paper records K may
be easily removed and referred for future reference, being held in place simply
by spring clips as shown.
It is true that the form of instrument shown is inaccurate when used as an
indicating instrument, since the ascending and descending values of the curve of
magnetization of ordinary iron are not coincident, but in this use, in which only
the maximum readings are important, it is possible to calibrate the instrument
with great accuracy.
In this specification and in the claims thereto attached the term stylus has
been used to indicate a pen or pencil, or any other instrument capable of making
a mark, though ordinarily it is preferred to use a pencil. It is obvious for
example, that a bristle moving over smoked glass will also serve. In addition it
will be noted that we have spoken of paper, or similar material meaning by
that term to include any substance capable of receiving and preserving an im-
pression from any of the devices mentioned above.
Having now particularly described and ascertained the nature of our said
invention (as communicated to us from abroad) and in what manner the same
is to be performed, we declare that what we claim is:-
1 In an electric meter system the combination with a stylus, whose motion
is a function of the current to be measured, with a fixed material capable of
receiving an impression from the stylus, whereby the stylus will trace on the
material a line whose length indicates the maximum value desired.
2-In an electric meter system, the combination with a recording, integrating
instrument, of a maximum indicating instrument, composed of a solenoid coil
acting on a core and moving a stylus, in series therewith.
3 In an electric meter system the combination with a solenoid and an iron
core, of an arm moved by said solenoid, a stylus on said arm, and a fixed sheet
of paper or other material, over which the stylus moves.
4 In an electric meter system the combination of a stylus, a sheet of paper
in operative relation therewith, and clips for detachably securing said paper to a
proper support.
Dated this 4th day of October 1898.
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