Improvements in Apparatus for Indicating and Recording Electric Currents.
Year: 1894

page_text: Date of Application, 21st Dec, 1894
Complete Specification Left, 23rd Sept, 1895-Accepted, 26th Oct., 1895
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Indicating and Recording
Electric Currents.
I, ALEXANDER BEWICKE BLACKBURN of Bushbury Works, Wolverhampton
in the County of Stafford, Civil Engineer do hereby declare the nature of my
invention to be as follows:-
In instruments or apparatus for indicating and recording electric curients, such
as for instance voltmeters and ammeters, in which the indications are produced by
inductive action between electric curients and magnetic bodies one portion whereof
is movable the indications are liable to be objectionably affected by extraneous fields
produced by other currents or magnetic bodies in the neighbourhood. According
to our invention we employ two coils with a common axis and a small space
between them they being joined in series but wound so that the electric current
passes through them eveise directions. Movable magnetic bodies for the
respective coils are attached to a spindle common to both of the said coils the said
magnetic bodies being so disposed that whilst the magnetic body appertaining to
the one coil is attracted or repelled by that coil in the same direction as that in
which the magnetic body appertaining to the other coil is attracted or repelled
the polarities required by each of the said magnetic bodies are in different
directions and as the strength and direction of the extraneous fields on each half
of the instrument will be nearly uniform the disturbing effects on the readings of
the instrument are diminished. A stationary magnetic mass may also be inti oduced
with each coil in order to intensifying the effect of the currents through tho
coils
upon the aforesaid movable magnetic bodies.
Dated this 21st day of December 1894.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, Agents.
Improvements in Apparatus for Indicating and Recording
Electric Currents.
I, ALEXANDER BEWICKE BLACKBURN of Bushbury Works, Wolverhampton
in the County of Stafford, 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:-
In instruments or apparatus for indicating, and recording, electric currents,
such as for instance, voltmeters, and ammeters, in which the indications aro
produced by mductive action between electric currents and magnetic bodies, one
portion whereof is moveable, the indications are liable to be objectionably affected
by extraneous fields produced by other curients, or maguetic bodies, in the
neighbourhood. According to my invention employ two coils with a common
axis and a small space between them, they being joined in series, but wound so
that the electric cutient passes through them in resorse directions. Moveable
1707

page_text: magnetic bodies for the respective coils are attached to a spindle common to both
of the said coils and having attached to it the indicating pointer of recorder, the
said magnetic bodies being so disposed that whilst the magnetic body appertaining
to the one coil is attracted, or repelled, by that coil in the same duection as that
in which the magnetic body appertaining to the other coil is attracted, or repelled,
the polarities acquired by each of the said magnetic bodies are in different
directions, and as the strength and direction of the extraneous fields on each half
of the instrument will be nearly uniform the disturbing effects on the readings
of the instrument aic diminished. A stationary magnetic mass may also bo
introduced within each coil in order to intensity the effect of the currents through
the coils upon the aforesaid moveable magnetic bodies.
In the accompanying drawing 1 bave shewn in longitudinal and transverse
sections respectively in Figures 1 and 2 suficient of an instrument provided with
my invention to illustrate the same. Figure 3 is a plan of the arrangement within
the coils. AA are the two coils arranged and wound as berembefore described.
B is the pointer and C the spindle thereof and D. E are the magnetic bodies
couuected to the said spindle one being situated in each coil A as herembefore
described and FG. are statiouniy magnetic masses and h is an adjustable balance
weight. I do not linnt myself to the precise details shown in the drawing.
Having now particularly described and ascertained the nature of this inven
tion and what manner the same is to be performed, I declare that what I
claim is
1. In apparatus for indicating and recording elective currents the combination of
two coils joined in sees and wound so that the current passes in the one in the
leverse dnection to that in which it pisses in the other and magnetic bodies
arranged so as to have movement imparted to them in the same duection substan-
tially as her onbefore described.
2. An apparatus for indicating and recording electie curients aanged as
herembefore described and illustrated in the accompanying drawings.
Dated this 21st day of September 189 ›
JOHNSONS & WILLCOX,
47 Lincoln's Jun Fields, London, W.C., Agents for the Applicant.