Apparatus for Regulating or Measuring Electric Currents.
Year: 1895

page_text: Date of Application, 17th July, 1895--Accepted, 17th July, 1896
Apparatus for Regulating or Measuring Electric Currents.
I, HENRI PIEPER (fils) Rue des Bayards, Liège, 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 apparatus forming the subject of the present invention is based upon the
principle of the expansion of a metal wire heated by the passage of an electric
current and is used for regulating or measuring electric currents.
If an electric current is allowed to pass through a metal wire this latter is heated
and commences to expand; in order however to obtain any considerable extension
a very long wire has hitherto had to be used and subjected to the action of an
exaggerated degree of heat.
a
The present invention consists of an apparatus by the aid of which the extension
of a metal wire can be multiplied within very large areas. In this way by using
wire of small length and by moderately heating it the extension of the said wire
caused by the passage of the electric current-can be used either for measuring
the current running through it or for regulating any desired apparatus.
This apparatus is shown carried out in several ways in the accompanying
drawing.
In the arrangement or form shown in Fig. 1 a metal lever A is pivoted or placed
so as to rotate around the axle B a metal wire D is joined to the end C of this lever
its other end being made fast to the screw nut or connection E. The entire system
forms a triangle the points of which lie at B C and E. If an electric current is
transmitted through the wire D and the lever A the wire gets heated and expands
whilst the lever-which is of a large size in cross section thus offering but little
resistance to the electric current-does not get heated.
It the apparatus is placed so that the weight of the lever continually tightens
the wire D the lever will then fall and thus for instance occupy the position shown
by the dotted lines in Fig. 1. If the electric current no longer passes through the
wire this latter then begins to cool down and contract and the lever A again takes
up its former position.
It may easily be seen from Fig. 1 that even with a very slight expansion of the
wire D very considerable displacements of the point C can be effected. These
displacements become all the larger in ratio to the expansion of the wire D according
as the distance between the points E and B is made smaller.
To further increase the motion thus obtained without having to approach the
points E and B too close to one another several levers can be arranged as per the
method or arrangement shown in Fig. 2, in which one end of the wire D is made
fast at the fixed point E and the other end joined to the end C of the lever A
pivoted at B while a second wire I joined to the said end C of lever A. is at its other
end joined to the end H of the lever F pivoted or adapted to rotate at G; so that
not only is movement caused to the lever F by the expansion and contraction of
the wire but the latter in addition is itself bodily moved by the expansion and
contraction of the wire D acting on the end of lever A.
From this figure it can easily be seen that the movement is very considerable.
This apparatus can be used either for regulating any desired electrical apparatus
as for instance with arc lamps the said movement of the lever being used for
moving nearer or taking away the carbons-or for measuring electric currents
(i.e. showing the strength of electric currents).

page_text: Fig. 3 shows the apparatus as adapted for the measurement of electric currents.
For this purpose a plate A of metal or other suitable material is fastened to an
insulation plate B upon the latter is pivoted or there rotates around the point Ca
metal lever D the other end H of which is joined to the expanding wire E and this
latter is connected with the circuit wires by means of the ordinary connecting
screw F. The fixed end of the lever D is connected with the ordinary connecting
screw G hy means of a slack wire the free end H of the lever D is connected with
a wire which encircles or partly encircles and is fixed to the reel I. The reel I is
pivoted or rotates on the axle K and carries a hand or pointer J which travels
over a sheet of paper provided with a graduated scale or other suitable index and
thus shows the strength of the current passing through the wire E. The current
enters through the connection-F-and-passes-through the wire E and the lever D.
The apparatus is regulated or formed in such a way that the hand normally stands
at "0" when no current is passing through the wire.
If a current is allowed to pass through the wire E and the lever D the wire gets
hot whilst the lever-which is of a large size in cross section-does not get hot.
The lever D owing to the heating and expansion of the wire E takes up the
position shown by the dots and this movement of the lever is transmitted to the
reel I and the hand J as explained.
In this way a large sweep of the index finger J can be made with a very slight
expansion of the wire E.
In order to protect the readings of the apparatus from being affected by the
outside temperature I have employed the following methods.
The object of the first method see Fig. 4 is to keep constant or uniform the
length E D of the expanding wire E in spite of the changes in the temperature the
expansion of the said wire being opposed by the displacement of the end of a
highly-expansive metal bar Z. To this end the wire E runs over a reel v and is
secured to the end S of the lever Z but insulated therefrom and is connected by
means of a loose wire with the current intersector H and is separated from the
bar Z by means of an insulation plate of zinc or other metal. The other end of
the bar Z is slotted and geared into a screw nut by the aid of which the bar is
fastened transversely on the prolongation of the plate B; or this slot can be
dispensed with the bar Z being screwed directly on to the plate B if desired.
The second method (see Fig. 5) is based on the supposition that the point B is
immutably fixed upon a sole-plate a and that the point E is located on a flat bar Bb
or on a very expansive sheet of metal the regulation of this bar can be effected by
providing it with a slot in which is fastened the head 6 of an arm bE made of some
material of low expansive degree. Hereby the point of fixture E of the expansive
wire is displaced owing to the change of temperature in the direction of 6 E as
the bar E is only fastened at b.
This arrangement corrects the effects of exterior change of temperature upon the
jointed triangle EC B. The corrections due to the expansion of the other parts of
the apparatus are eliminated if the bearings or supports of the fixed points of the
movable system are made of the same or equal material a wire being used as
suspensors which is just as expansive as the bearing plate.
In order to use the apparatus as a volt measure (volt meter) a resistance is run
into the wire E a very fine thin wire being used.
In order to prevent the metal wire from fusing or injury if too powerful a
current is passed through the apparatus the following method is employed:-
The screw nut F (Fig. 3) is connected by means of a wire with the insulated
portion L of the plate A. When too powerful a current passes through the
wire E the lever D sinks so far until its end H touches the part L. As the nut F
is connected with the part L by a wire of very low resistance the current takes.
this latter course and the wire E is thus relieved and protected.
Fig. 6 shows the apparatus as adapted for regulating electrical apparatus :—
The movement of the indicator K is clearly to be seen from the drawing. As
this figure shows the indicator K not only indicates the manner in which the:

page_text: alteration of the current takes place but by help of a contact block is able to
create or remove resistance. In the position shown in the drawing the current
from the battery E is able to pass over 1, 2 indicator K, contact 4, con-
ductors 5, 6. 7, 8 to the battery. If now the indicator K be moved so as to reach
one of the contact blocks connected together by means of the resistance R more or
less resistance R is created in the circuit and the current compelled to pass through
this resistance.
The battery El may be the same as that shown in Fig. 3 in which case the
electrical connection must be so arranged that the current cannot directly pass over
the wire E to the arm D but must first pass through the indicator K and the
conductors 1, 2, 3, 4, 5, 6, 7, 8. The turning point I of the indicator K is then
connected by any suitable conductor with the wire E which is tben insulated from
the arm D whilst the latter is brought into connection with the conductor 5. The
indicator K is able to execute any mechanical movement which may be made
use of to actuate an electrical regulating apparatus of any suitable kind. This
indicator as already set forth in the specification can therefore for instance
operate the carbon rod of an electrical arc lamp and so by the altered strength
of the current affect the distance of the two carbon pieces that is the length of the
arc light.
In the method above described the levers can be replaced by pliable metat
tongues or blades in the form of springs and are thus always endeavouring to
tighten or span the wire. The current could also be sent only through the wire
instead of through the wire and the lever or the pliable tongues of metal.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In an apparatus for regulating or measuring electric currents-the com-
bination with a pivoted lever of a fine wire connected to the free end of said lever
at an acute angle thereto in the form of a triangle in such manner that when
the said wire is expanded by heat induced by its resistance to the current passing
therethrough thereby said lever receives relatively a very large movement.
2. In an apparatus for regulating or measuring electric currents-the com-
bination with a pivoted lever of a fine wire connected to the free end of said lever
at an acute angle thereto in the form of a triangle in such manner that when the
said wire is expanded by heat induced by its resistance to the current passing
therethrough thereby said lever receives relatively a very large movement substan-
tially in the manner and for the purposes hereiubefore described.
3. The arrangement and construction of apparatus substantially in the manner
and for the purposes herein before described with reference to Fig. 1 of the drawings
hereunto annexed.
4. The arrangement and construction of apparatus substantially in the manner
and for the purposes herein before described with reference to Fig. 2 of the drawings
hereunto annexed.
5. The arrangement and construction of apparatus substantially in the manner
and for the purposes hereinbefore described with reference to Fig. 3 of the drawings
hereunto annexed.
6. The arrangement and construction of apparatus substantially in the manner
and for the purposes herein before described with reference to Fig. 4 of the drawings
hereunto annexed.
7. The arrangement and construction of apparatus substantially in the manner
and for the purposes hereinbefore described with reference to Fig. 5 of the drawings
hereunto annexed.
8. A safety arrangement for preventing over heating of the wires in apparatus
such as described consisting of a current-intersector such as L Fig. 3 so disposed
that when the wire is heated to a certain degree it automatically permits the current

page_text: to pass through another circuit and so relieves the fine wire substantially in the
manner and for the purposes hereinbefore set forth.
9. The improved apparatus arranged constructed combined and acting substan
tially in the manner and for the purposes herein before set forth.
Dated this 17th day of July 1895.
TONGUE & BIRKBECK,
Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.
TONGUE & BIRKBECK,
Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.