Improvements in Electricity Measuring Instruments.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electricity Measuring Instruments.
We, ARTHUR ANNESLEY VOYSEY, of the Wool Exchange, Basinghall Street, in
the City of London, Electrical Engineer, and REGINALD PAGE WILSON, of 68,
Victoria Street, in the City of Westminster, Consulting Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention relates to electricity meters wherein an instrument of the elec-
trostatic voltmeter type is employed, and consists in the adaptation of such an
instrument in conjunction with a transformer and switch mechanism to perform
alternatively the functions of an ampère-meter and of a volt-meter.
Heretofore instruments known as electrostatic volt meters have been con-
structed on the principle of the mutual attraction existing between oppositely
charged bodies, and employed in measuring the difference of potential between
two points in an electric circuit.
The present invention comprises means for rendering such an instrument, or
similarly operated instrument, capable of employment in an alternating current
circuit, either as a volt-meter or an am-meter.
In carrying out our invention, any suitable electrostatic instrument may be
used. For performing the function of a voltmeter, in the ordinary way, this
instrument is connected with the main conductors in the following manner:-The
spindle of the electrostat whereon the moveable plates are arranged is connected
by means of a wire with one of the main conductors of an electric circuit, while
the fixed plates are in electrical connection by means of a wire with the other
main conductor; the difference of potential between the two points of connection
with the main conductors being shown by a suitable indicator. In employing
the electrostat as an ammeter, a transformer is interposed between the voltmeter
and the main conductors; the "primary" of the transformer being connected in
series with the main conductor, while the terminals of the "secondary" are con-
nected the one to the spindle carrying the moveable plates and the other to the
stationary plates. The electrostat is thus influenced in proportion to the current
passing through the primary coil because the difference of potential at the ter-
minals of the secondary coil varies with the primary current. By constructing a
suitable scale to indicate the current flowing through the primary according to
the varying positions of the moveable plates in the electrostat, the instrument
becomes an ammeter.
In order to render the electrostat, connected with the main source of electrical
energy in the manner above described, available for performing alternatively the
several functions of a voltmeter and an ammeter, it is necessary to provide the
instrument with a special pointer and a distinct scale suitable for each function
performed, and with switch mechanism, whereby the particular connections may
be established for effecting the desired indication.
We would observe that the transformer herein referred to is one which has no

page_text: iron in the magnetic circuit and therefore one in which the induction is propor-
tional to the current in the primary. The current in the secondary will, for all
practical purposes, be negligible.
1071
1000
Improvements in Electricity Measuring Instruments.
We, ARTHUR ANNESLEY VOYSEY, of The Guildhall, formerly of the Wool
Exchange, Basinghall Street, in the City of London, Electrical Engineer, and
REGINALD PAGE WILSON, of 68, Victoria Street, in the City of Westminster, Con-
sulting 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:-
This invention relates to electricity meters wherein an instrument of the elec-
trostatic voltmeter type is employed, and consists in the adaptation of such an
instrument in conjunction with a transformer and switch mechanism to perform
alternatively the functions of an ampère-meter and of a volt-meter.
Heretofore instruments known
structed on the principle of the
charged bodies, and employed in
two points in an electric circuit.
as electrostatic volt-meters have been con-
mutual attraction existing between oppositely
measuring the difference of potential between
The present invention comprises means for rendering such an instrument, or
similarly operated instrument, capable of employment in an alternating current
circuit, either as a volt-meter or an am-meter.
The accompanying drawing is a diagrammatic view illustrating the method of
employing an electrostat as a volt-meter and an am-meter.
In carrying out our invention, any suitable electrostatic instrument may be
used. For performing the function of a volt-meter, in the ordinary way, this
instrument is connected with the main conductors in the following manner:-The
spindle a of the electrostat whercon the moveable plates al are arranged is con-
nected by means of the wire a² with the main conductor a³ of an electric circuit,
while the fixed plates 6 are in electrical connection by means of a wire bl with
the main conductor ; the difference of potential between the two points of
connection with the main conductors being shown by a suitable indicator, not
illustrated. In employing the electrostat as an am-meter, a transformer cc is
interposed between the volt-meter and the main conductors 3 and 62; the
primary c of the transformer being connected in series with the main con-
ductor, while the terminals of the "secondary" c¹ are connected the one to the
spindle a carrying the moveable plates a¹ and the other to the stationary plates b.
The electrostat is thus influenced in proportion to the current passing through
the primary coil because the difference of potential at the terminals of the secon-
dary coil varies with the primary current. By constructing a suitable scale to
indicate the current flowing through the primary according to the varying posi-
tions of the moveable plates a¹ in the electrostat, the instrument becomes an
.
am-meter.
"
In order to render the electrostat, connected with the main source of electrical
energy in the manner above described, available for performing alternatively the

page_text: functions of a volt-meter and of an am-meter respectively, we prefer to provide
the instrument with a special pointer and a distinct scale suitable for each
function performed, and with switch mechanism, whereby the particular connec-
tions may be established for effecting the desired indication.
We prefer to construct the transformer with an air core.
Our invention, so far as it concerns the use of a volt-meter as an indicator of
current, may be applied to volt-meters other than electrostatic.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we claim:-
In an instrument for measuring either ampères or volts, the use of a trans-
former arranged in such a manner that when required to indicate ampères its
primary" may be connected in series with the main circuit and its “ secondary"
with a volt-meter, substantially as herein described.
"
For the Applicants,
G. G. M. HARDINGHAM,
Chartered Patent Agent,
Clun House, Surrey Street, London, W.C.
OCOL
SLITA