Year: 1887

page_text: Date of Application, 15th Jan., 1887
Complete Left, 17th Oct., 1887
Complete Accepted, 14th Jan., 1888
I, SEBASTIAN ZIANI DE FERRANTI of 5 Stanwick Road, West Kensington, in the
County of Middlesex, Electrician, do hereby declare the nature of this invention to be
as follows:-
:-
My improvements relate to electrical meters of that kind in which the current to
be measured is made to pass through a bath of mercury in a magnetic field so disposed
as to put the mercury into continuous movement whenever a current passes and in
which the movement of the mercury is recorded by causing it to impart a revolving
motion to an axis whose revolutions are recorded by a counter or in which the
movement of the mercury is recorded in other convenient way. An electrical meter
of this kind is described in the Specification of a former patent granted to me
No. 5926 in the year 1883. In these meters as heretofore constructed there has been
a pole piece of cast iron which retained a certain amount of residual magnetism and
this served to assist in causing rotation of the mercury whenever a feeble current was
passing and helped to start the meter.
An electric meter of this kind can be used advantageously for recording the passage
of a continuous current but for an alternating current it would be inadmissible to use
heavy blocks of magnetic metal the polarity of which would be constantly reversing.
I therefore in meters which are to be or which may be used for recording alternate
currents use pole pieces which do not retain residual magnetism and to effect the
object previously attained by the residual magnetism I use an additional coil or coils
of an insulated conductor around the pole pieces of the magnets. The current passed
through these additional coils forms no part of the circuit the current through which
is to be measured but is a branch circuit direct from the main conductor from the
dynamo to earth or to the return conductor. The same improvement is applicable to
all motor meters-that is meters in which the movement is obtained from the current
to be measured.
D
1008
CARPMAEL & Co.,
Agents for the Applicant.

page_text: DIECIFICATION.
Improvements in Electrical Meters.
I, SEBASTIAN ZIANI DE FERRANTI of 5 Stanwick Road, West Kensington, in the
County of Middlesex, Electrician, do hereby declare the nature of this invention
and in what manner the same is to bo performed to be particularly described and
ascertained in and by the following statement :-
My improvements relate to electrical meters of that kind in which the current to
be measured is made to pass through a bath of mercury in a magnetic field so
disposed as to put the mercury into continuous movement whenever a current passes
and in which the movement of the mercury is recorded by causing it to impart a
revolving motion to an axis whose rovolutions are recorded by a counter or in which
the movement of the mercury is recorded in other convenient way. An electrical
meter of this kind is described in the Specification of a former patent granted to me
No. 5926 in the year 1883. In these meters as heretofore constructed there has been
a pole piece of cast iron which retained a certain amount of residual magnetism and
this served to assist in causing rotation of the mercury whenever a feeble current was
passing and helped to start the meter.
An electric meter of this kind can be used advantageously for recording the passage
of a continuous current but for an alternating current it would be inadmissible to use
heavy blocks of magnetic metal the polarity of which would be constantly reversing.
I therefore in meters which are to be or which may be used for recording alternate
currents use pole pieces which do not retain residual magnetism and to effect the
object previously attained by the residual magnetism I use an additional coil or coils
of an insulated conductor around the pole pieces of the magnets. The current passed
through these additional coils forms no part of the circuit the current through which
is to be measured but is a branch circuit direct from the main conductor from the
dynamo to earth or to the return conductor. The same improvement is applicable to
all motor meters-that is meters in which the movement is obtained from the current
to be measured.
In the drawings annexed I have shewn examples of meters constructed as above
described.
Figure 1 is a vertical section and
Figure 2 a horizontal section of one form of meter.
Figure 3 is a vertical section and
Figure 4 a horizontal section of another form of meter-and Figures 5 and 6 are
diagram views to shew the way in which a branch circuit from the main conductors
is carried through the additional coil of the meters.
In Figures 1 and 2 A is a tubular stem with a disc B surrounding its upper end-
below this are radially slotted iron discs C with insulating material between them—
below these the tubular stem has thin iron coiled around it with insulating material
between succeeding layers-this coil D is held in place by a disc E secured to the
end of the stem A. Around the iron coil D is the additional coil F of fine insulated

page_text: wire and also the insulated coil G through which the current to be measured has
to pass.
- -
Below this is a brass metal ring H insulated from the disc E and iron coils-The
bottom of the central hole of the ring is closed by a plate I held firmly up against
tlio bottom of the ring with insulating material placed between the two. The upper
surface of the plato is enamelled and forms the bottom of the mercury bath of the
méter. J is a metallic stud passing through the centre of the plate I the upper
surface of this stud is uninsulated. The lower end of the stud is secured to a plate K
which carries one of the terminals as shown. Laro slotted iron discs placed between
the plates I and K. M are concentric cylinders of thin iron connecting the iron
discs C with the iron-discs-L. Each cylinder has a slot formed longitudinally
through it which in addition to preventing currents being set up in the cylinders also
allows of wire connections being carried through to the insulated wire coils. N is a
metallic plate placed below the iron discs L and insulated from them and from the
plate K. The plates K and N rest on the bottom of a tray. O. The tray is secured
within the outer casing P by means of sulphur poured when melted into semicircular
recesses formed along two opposite sides of the tray and corresponding recesses
formed on the interior of the casing as shown.
Beforo pouring. in the sulphur to secure the tray it is forcibly pressed towards the
upper end of the casing to clamp together the several parts above described and
whilst the parts are so clamped and held the sulphur is poured in and the tray thereby
securely held.
R is the central spindle of the meter with arms projecting from its lower end in
the mercury bath and at its upper end giving movement to a train of recording
wheels as described in the Specification of my former Patent.
The current from the mains enters the meter say at the terminal K passes to the
centre of the bath through the stud J and from the circumference of the bath to the
metallic ring H and from it to the inner end of the insulated wire coil G and fram
the outer end of this coil to the terminal N. The ends of the additional coil Faro as
before stated so coupled to the mains that a current passes through it continuously
without passing through the mercury bath.
The way
in which these connections may be made is illustrated in Figures 5 and 6.
In these figures W represents a dynamo ✗ conductors leading therefrom Y one of the
meters and Z Z a series of lamps.
In the meter shewn at Figures 3 and 4 A is a metallic cylinder closed at bottom
and filled with mercury, its interior is coated with shellac or other insulating material
except at the centre. B is a cylinder immersed in the mercury-it is formed of a
vertical stem of conducting metal with a collar projecting around it at the centre
and with insulated coils of thin sheet iron surrounding tho stem above and below the
collar. The lower end of the stem rests on a fixed pivot C which is in connection
with one terminal C₁ of the meter. The upper end of the stem or axis of the
cylinder B carries a weight D to keep the cylinder from floating in the mercury and
is also carried upwards and made to give motion to a train of recording wheels E
as shewn. F is a coil of insulated wire surrounding the cylinder A and through
which the current to be measured is passed and G is the additional coil of fine
insulated wire through which a branch circuit is conducted from the mains without
passing through the mercury bath of the meter.
The current to be measured enters the meter say at the terminal C¹ passes up
through the pivot C and radially outwards through the collar which surrounds it to
the cylinder A from this it passes to the inner end of the coil F and from the outer
end of the coil to the other terminal of the meter. The mercury set in rotation by
the passage of the current carries the cylinder B round with it and the axis of the
cylinder conveys movement to the axis of the first wheel of the train of recording
wheels.
I would remark that although in the drawings annexed I have only shown two
forms of meter having additional coils through which a branch circuit from the mains
is made to pass for the purpose above described I do not restrict my claim to the two

page_text: meters shown as my improvements can as before stated be applied to all motor meters
in which movement is obtained from the current to be measured.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is :-
1. The employment in electric motor meters of an additional coil of insulated
conductors through which a current not forming any part of the current to be
measured is passed continuously for the purpose herein before described.
2. Electric meters in which the pole pieces of the motor magnets are formed of
laminated wrought iron and are magnetized not only by the coil through which
the current to be measured passes but also by another coil or coils through which is
led a current that forms no part of the current to be measured.
3. The construction of electric meters substantially as herein before described and
illustrated at Figures 1 and 2.
4. The construction of electric meters substantially as herein before described and
illustrated at Figures 3 and 4.
CARPMAEL & Co.,
Agents for the Applicant.