improvements in Electrical Resistances.
Year: 1899

page_text: improvements in Electrical Resistances.
I, MAX LEVY, Electrician, of 2A, Chaussee Strasse, Berlin, in the Empire of
Germany, do hereby declare the nature of this invention to be as follows:-
The arrangement hitherto adopted in electrical resistances in which resistance
wires, strips, bands, etc., are attached to and insulated from a metallic support-
5 ing plate by means of enamel glass, insulating cement or the like has the great
disadvantage that, in the event of any defect arising, for example in a wire, or
band, at a particular spot whether through overcharging or physical injury,
repair is generally impossible and the apparatus rendered unserviceable. Hence
the charging in these larger surfaces must not be so heavy, as the enamel
easily flies in pieces in those spots where the parts of the resistance which are
out of circuit and those which are heated under the current come into contact
with one another. Finally large enamel surfaces are difficult to produce.
All these disadvantages are obviated by the present invention, according to
which, instead of the resistance being secured to a large supporting plate a
number of small elements, sections, or strips are employed, which can be arranged
in a special frame so as to be put together at will.
In carrying out the invention I provide a cast-iron frame, in which the several
elements, preferably furnished with ribs on account of the giving off of heat, are
inserted adjoining one another and held firm by means of a common stay, so
that they can expand or contract according to the degree to which they are heated.
The elements which, likewise, are preferably made of cast-iron, or sheet iron,
carry at the back the resistances, which are firmly connected with, yet insulated
from the metal foundation or support by means of enamel or other suitable
nsulating material. Every element constitutes a resistance in itself. Those
with fused in connecting wires serve as a connection with insulated contact pieces
rranged on the cast iron frame, on which contact pieces the contact spring of
he regulating lever can be moved to and fro. The changing of an element is
ffected by loosening screws holding the common or mutual stay, and then break-
g the connection between the changeable element and the corresponding con-
cts.
In a modified form of construction the several elements are combined together in
circular frame and somewhat like a fan. In this case, the regulating contacts
n be arranged on the elements themselves.
Where the regulation needs to be very precise, the regulating contact may also
de directly on the resistance bands embedded edgeways in enamel. In this case :
regulation from coil to coil is possible. This arrangement is desirable for
tance, in arc lamps and shunt current resistances (dynamo field resistance).
This novel arrangement of the resistances has the further advantage that the
eral elements can be produced separately from one another, and with a mould
the size of the iron frame the resistance elements for diff
[Price 1

page_text: put together at will and changed or interchanged without any disturbance of the
other elements.
The fixing of the several elements can also be effected, as a matter of course,
in many other ways. They can also be inserted one behind the other or parallel
to one another.
With the improved resistance a more powerful charge can be used than has
hitherto been possible with equal cross section of the resistance material and
equal radiating surface, thereby effecting economy of space and weight, and
further any damage at a particular spot only renders a small part of the par-
.ticular resistance unserviceable, not the whole, and this can be taken out and
changed by any unskilled person..
Dated this 12th day of May 1899
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.
Improvements in Electrical Resistances.
I, MAX LEVY, Electrician, of 2A, Chaussee Strasse, Berlin, in the Empire of
Germany, 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 arrangement hitherto adopted in electrical resistances in which resistance
wires, strips, bands, and the like, are attached to and insulated from a metallie
supporting plate by means of enamel, glass, insulating cement or the like has
the great disadvantage that, in the event of any defect arising, for example in
a wire, or band, at a particular spot whether through excess of pressure or physical
injury, repair is generally impossible and the apparatus rendered unserviceable.
Hence the pressure of the current in these larger surfaces must not be so great,
as the enamel easily flies in pieces especially in those spots where the parts of
the resistance which are out of circuit and those which are heated under the
current come into contact with one another. Finally large enamel surfaces are
difficult to produce.
All these disadvantages are obviated by the present invention, according to
which, instead of the resistance being secured to a large supporting plate a
number of small elements, sections, or strips etc., are employed, which can be
arranged in a special manner so as to be put together at will.
In the accompanying sheet of illustrative drawings: Fig. 1 comprises a plan,
cross sections at right angles, and a detail view of a single element, of a resistance
constructed according to this invention, Fig. 2 is a plan and sectional elevation
of a resistance of modified construction. Figs. 3, 4, and 5 show further modified
forms of resistance.
In carrying out this invention Fig. 1 shows for instance a cast-iron frame r
in which the several elements e preferably furnished with ribs on account of the
giving off of heat. are inserted adjoining one another and held firm by means
of a common stays, so that they can expand or contract according to the degree
to which they are heated.
The elements e which, likewise, are preferably made of cast-iron or sheet iron,
carry at the back the resistances which are firmly connected with, yet in-
sulated from the metal foundation or support by means of enamel or other suitable
insulating material. Every element constitutes a resistance in itself. The con.

page_text: ecting wires, serve as a connection with insulated contact pieces e arranged
on the cast iron frame, on which contact pieces the contact spring f of the regu-
lating lever can be moved to and fro. The changing of an element is effected
by loosening screws a', a² holding the common or mutual stays and then break-
ing the connection between the changeable element and the corresponding
contacts .
'
In a modified form of construction Fig. 2 the several elements are combined
together in a circular frame and somewhat like a fan.
regulating contacts can be arranged on the elements e themselves.
In this case, the
Fig. 3 represents separate resistance elements e¹, e² arranged concentrically to
one another. This figure shows at the same time a new kind of regulating
arrangement and one which is especially delicate, shown more clearly in Fig. 4
in which the regulating contact g slides directly on
embedded edgeways in enamel. In this case a regulation from coil to coil is
the resistance bands h
possible. This arrangement is desirable for instance in shunt current resistances
(dynamo field resistances) and in are lamps.
The fixing of the several elements can also be effected, as a matter of course,
in many other ways. They can also be inserted one behind the other.
Fig. 5 for example represents a carriage resistance for electric railways, etc.
The elements are of equal size arranged simply one behind the other. In this
resistance the contacts are dispensed with as the regulating is effected at the
controller.
°
With the improved resistance a more powerful current can be used than has
hitherto been possible with equal cross section of the resistance material and
equal radiating surface, thereby effecting economy of space and weight and
further any damage at a particular spot only renders a small part of the par-
ticular resistance unserviceable, not the whole, and this can be taken out and
changed easily.
Having now particularly described and ascertained the nature of my said
nvention and in what manner the same is to be performed, I declare that what
claim is:
1. In electrical resistances in which the resistance wires or the like are
ttached to but insulated from a metallic support, constructing the resistance of
number of separate elements each consisting of a separate resistance and sup-
ort, the several elements being arranged in a metal frame and each element
aving a contact so connected and working in conjunction with a contact lever
ounted on the frame that the element can be brought into circuit.
2. The improved electrical resistance substantially as described with reference
Fig. 1, or to Fig. 2, or to Fig. 3, or to Fig. 4 or to Fig. 5 of the drawings.
Dated this 12th day of February 1900.
WHEATLEY & MACKENZIE.
40, Chancery Lane, London, W.C., Agents.