Improvements in Connections or Couplings for Glow Lamps and the like which cannot be Interchanged.
Year: 1899

page_text: Date of Application, 5th July, 1899-Accepted, 30th Sept., 1899
Improvements in Connections or Couplings for Glow Lamps and the
like which cannot be Interchanged.
We, SIEMENS BROTHERS & Co: LIMITED, of 12, Queen Anne's Gate, West-
minster, S.W., Electrical Engineers, do hereby declare the nature of this inven-
tion (as communicated to us from abroad by Siemens & Halske Aktien Gesell-
schaft, of Markgrafen Strasse No. 94, Berlin, S.W.,, Electrical Engineers,) and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
In most electrical work safety devices are prescribed for installations where-
by the inadvertent use of safety fuses of two great strength is rendered impos-
sible. For those electrical works that supply electricity at a fixed charge the
problem requires to be solved' how to prevent the fradulent employment of lamps
that consune too much current.
.
Both for safety fuses and for glow lamps and their fittings arrangements have
consequently been provided which are intended to prevent the incorrect use of
interchangeable insertion pieces (safety stopper and glow lamps) in frames or
fittings which are only intended for a certain kind of insertion piece.
All arrangements heretofore proposed for the above purpose, however, suffer
from certain disadvantages. For instance some of the constructions suffer from
the disadvantage that the fittings are externally of varied form or size, and that
the construction does not admit of easily effected alterations, which is however
very desirable for various reasons.
According to the present invention the above problem is solved in such manner
that while a uniform method of constructing the main parts is strictly main-
tained the necessary variations of the separate parts is effected by the introduc-
tion of a single constructional device.
We will describe the invention with reference to the accompanying drawings,
from which it will be seen that the external screw contacts of the variously
formed glow lamp bases, and consequently also the fittings thereof, are all
identical in form while the inner contacts alone are made of varying diameters.
In the arrangement shewn at Figs. 1 to 3, the inner contact of the glow lamp
has a projecting pin 22, 23, of different thickness for different lamps, a lamp
of low candle power (Fig. 1) having a contact pin z', of smaller cross section
than that of the contact pin of a high candle power lamp (Fig. 3).
In the setting of the lamp there is a discs, 3, 3, either made of insulating
material or duly insulated with a central opening above the inner contact of the
setting of a size corresponding to the power of the lamp for which it is intended
so that when a lamp of too high candle power is inserted, the closing of the
circuit by the contact is prevented. This insulating disc may for example, be
cemented in the insulating block as shewn in Fig. 1, or it may be mounted on
two independent screws (Fig. 2) or it may be flanged and screwed on to the
insulating block (Fig. 3).
In the arrangement shewn at Figs. 4 to 7 the pins of different thicknesses m¹.
m2, m³, of the inner contact are placed in the setting and the bases of the glow

page_text: lamps have correspondingly deeply set contacts which are surrounded by the
projecting edges r, 2, 3, made of porcelain or the like and forming cavities of
different diameters corresponding to the size of contact m for which the lamp
is intended. Fig. 7 shews the lamp base of Fig. 4 applied to the setting of
Fig. 5, from which it will be seen how in the event of such a false application
being made the closing of the circuit is prevented.
In the arrangement shewn at Figs. 1 to 7 only a variation of the setting by
the addition or alteration of one constructional device have been considered:
It is desirable to apply the principle of the invention to interchangeable set-
tings, that is, to have safety plugs and glow lamps so constructed that fusible
plugs of different degrees of sensitiveness and glow lamps of different candle
power, (which however can be made to a standard pattern with similar contact
bases) may be used in frames or settings which are provided for particular
fittings.
Figs. 8 to 11 show a construction for this purpose which, like that shewn in
Figs. 1 to 3, permit of the use of glow lamps with the usual Edison screw base.
In Fig. 8 is shewn such a lamp base with a sheet metal cap fitted (soldered) on
its inner contact, which cap carries a projecting stud z¹.
Fig. 9 shews a series of such caps with studs 21, 22, 23, 24, for different candle
powers, such as 10; 16, 25, 32 Kefner-candles for which the diameters of the
projecting pins may be, for example 3, 5.5, 8, 10.5 mm.
Fig. 10 shows a corresponding series of insulating discs st, 2, 3, 4, having
openings of slightly wider diameters than those of the corresponding studs,
such as 3.5, 6, 8.5, 11 mm.
These insulating discs may be set in the bottom of the normal setting over
the inner contact and be kept in place in the screw shell either by projections v, v,
as at Fig. 11 or by spring tongues, notches or the like.
To facilitate the insertion of the lamp in the setting and to provide also for
the case in which the central pin of the lamp and the hole in the insulating
dise of the setting are not quite concentric the meeting edges of the pin z and
the discs may be suitably rounded.
The arrangements here described for glow lamps and settings are equally as
well applicable to other purposes where non-interchangeable circuit closing
contacts are desired, particularly to fusible plugs and the safety frames belonging
thereto.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
Circuit closing contacts having contact pins, studs, or devices of different
sizes so that a lamp or plug of high power cannot be fitted to a setting intended
for low power, the lamp or plug and their setting being constructed in the usual
manner, while the said contact pins, studs, or devices of varying sizes are
separately attached thereto, substantially as described.
Dated this 5th day of July 1899.