Year: 1887

page_text: [Communicated from abroad by GEORGE WESTINGHOUSE, Junior, of Pittsburg, County
of Alleghany, State of Pennsylvania, United States of America, Engineer.]
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, and 6 Bank Street, Manchester, both in the
County of Lancaster, and 323 High Holborn, in the County of Middlesex, Civil
Engineer, 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 relates to the class of apparatus employed for measuring electric
currents.
The object of the invention is to provide means for securing as great an amplitude
of movement of an indicating device as possible from a given variation in the electro-
motive force of the current traversing the same, and to reduce to a small fraction the
error due to the change in resistance of a metallic coil.
One or more electric lamps are introduced in the circuit, in series with the coil of
the indicator. These serve to increase the effect due to any variation, by reason of the
change which occurs in their own resistance under the influence of an increase or
decrease in the electro-motive force of a current traversing the indicator coil.
The accompanying drawings illustrate the general organization of apparatus
embodying the features of the invention :-
Referring to Figure 1, L2 represents a circuit traversed by currents, the variations of
which it is desired to measure, and a² represents the coil of the electric meter. This
coil is provided with a core 6 suspended upon a pivoted lever or beam B supported
at b. It is provided with a suitable counterpoise 6. The beam B carries an
indicator c moving over a scale C. In series with the coil A which is of small resist-
ance there are inserted one or more incandescent electric lights d', d', d¹. Whatever
variation in the current occurs, causes the indicator c to respond accordingly, but this
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page_text: variation is augmented by the presence of the lamps, for the reason that as the electro-
motive force increases, the resistance of the lamps decreases proportionately, and
vice versa.
The small resistance of the coil relative to the entire resistance of the
circuit in which it is included will, it is evident, reduce to a minimum the error due to
the change produced by the heating of the conductor. It is designed that the meter
shall be included in multiple-arc circuit with the translating devices which are being
supplied.
It is preferred to divide the conductor into branches L1 and L2, as shown in Figure 2.
These unite in the line L³. In the branch L' there is included the coil a¹ of the
indicating device. The other branch L², includes the second coil a² of this instrument.
The two coils are respectively provided with cores and 2 suspended from the cross
arm or scale beam B.
The branch L contains the incandescent electric lights d' d¹. A resistance R',
equivalent to the resistance of the lights when operating at normal brilliancy, is con-
tained in the line L'. An adjustable resistance R' may be added to the resistance R¹
in the branch L', to render the balance more perfect.
The resistance device in the branch L' should be different from that in the line
branch L, thus if the latter is carbon, the former may be metallic. The two will
therefore be differently affected by the heat developed by the currents traversing the
branches.
Any increase in the current traversing the lines L and L³, will correspondingly
increase the current traversing the branches. L' and L2, but the relative current in
these two lines will vary with reference to each other, by reason of the variation.
produced in the artificial resistance R¹ with reference to that in the lamps, by the
increase of the current. This will in turn affect the current traversing the
coils a¹ and a², and disturb the equilibrium of the indicator c and this will be indicated
upon the scale C.
In this manner the attendant will be able to note any variation in the work done in
the external circuit, and adjust the current supply accordingly.
There may be some disadvantages, in some instances, in having the coils a¹, a² upon
opposite sides of the axis b, for they tend to increase the pressure of the cross-arm B
upon the axis or bearing. To avoid this the arrangement shown in Figure 3 may be
adopted. In this instance a weight e takes the place of the core 2 upon one side of
the axis, and the coil a² is transferred to the opposite side, and tends to lift the core b³,
in opposition to the action of the coil a¹ upon the core b¹.
A still more perfect balance may be obtained by the arrangement illustrated in
Figure 4. In this instance four coils are employed. The coil a¹ is included in the
line L', together with a second coil a and the coil a³ is supplemented by a coil a' in the
line L. The coils a¹ and a³ act upon these cores in the same manner as indicated in
Figure 1, but the coils a³ and a act upon the cores 63, 6*, extending upon opposite
sides of the support E, and this lessens the pressure upon the bearing. The operation
of this device is similar to that of the other two already described.
In Figure 5 another arrangement is illustrated. This consists in placing the coils at
an angle with reference to each other, and in extending a curved core into both as
shown at 6, 6. In this instance the pointer or index c extends downward from the
support b.
.
In each of the Figures 2, 3, 4, and 5, one or more lamps d are included in the
conductor L or L for reducing the current through the conductors and rendering the
error due to changes in the resistance of the coils less.
Having now particularly 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 :-
1. In an electric meter, the combination with the coil of the meter, having a com-
paratively low resistance, of a series of incandescent electric lamps having a relatively
high resistance and connected in series therewith, and reducing the error due to the
change in the resistance of the coil.

page_text: 2. The combination in an electric meter, of the indicating device, the coil for
actuating the same, connected in multiple arc with the translating devices, and one
or more incandescent electric lamps of relatively high resistance connected in series
therewith, reducing the error due to the change in the resistance of the coil.
3. The combination of a conductor, two branch circuits, two coils respectively
included therein, an indicator acted upon by said coils in opposite directions, a carbon
resistance in one of said branches varied as to its value by the current traversing the
same, and an incandescent electric lamp in the conductor.
4. The combination with a main line and translating devices included in the main
line varying the amount of current traversing the same, of an electrical indicator
included in multiple-arc circuit with the translating devices, consisting of opposing
coils, an index acted upon thereby, branch circuits respectively including said coils, a
variable resistance included in one branch circuit, and a carbon resistance in series
with the indicator.
5. The combination with a conductor and two branch circuits, of a volt-meter con-
sisting of an indicator, two coils respectively included in the branch circuits of said
conductor, cores therefor carried by the support of said indicator, and means for
counterbalancing the weight of said cores.
6. The combination with a conductor and two branch circuits, of a volt-meter
consisting of a resistance included in one branch and one or more translating devices
in the other branch, and two coils in each branch respectively provided with cores, the
two coils in one branch acting in opposition to the two coils in the other branch, sub-
stantially as described.
7. The combination substantially as described, of a main line having two branches, a
resistance in one branch, a translating device in the other branch, two coils
respectively included in said branches, and placed at an angle to each other, a core
extending into both of said coils, and a central support for said core.
Dated this fith day of July 1001.
WM. P. THOMPSON & Co.,
Agents for the Applicant.
WM. P. THOMPSON & Co.,
Agents for the Applicant.