Improvements in Switching Gear for Transformers, Reactance Coils, Storage Batteries, and the like.
Year: 1897

page_text: . Date of Application, 11th Nov, 1897-Accepted, 29th Jan., 1898
COMPLETE SPECIFICATION.
Improvements in Switching Gear for Transformers, Reactance Coils,
Storage Batteries, and the like.
We, THE BRITISH THOMSON-HOUSION COMPANY LIMITED, and HENRY METCALF
HOBART, all of 83, Cannon Street, in the City of London, Electrical Engineers,
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:
This invention has for its object to provide simple switching gear capable of
very fine adjustment and suitable for easily and accurately changing and varying
as required either the number of active turns in circuit in either of the coils of a
transformer or in a reactance coil, or the number of active cells of storage batteries.
By the use of this invention excessive flow of current during operation of the switch
gear is avoided owing to the use in combination of a stationary reactance coil or
resistance as the case may require. The invention lies in the means for effecting
the above objects and in the mechanical arrangement of the parts, and we will
now describe our improvements in reference to a transformer and to a battery;
its adaptability to other electrical apparatus will be readily understood by com-
petent electricians.
Fig. 1 is a diagram illustrative of our invention as applied to a transformer and
Fig. 2 to a storage battery and the remaining figures illustrate the mechanical ar-
rangement of a switch in which the invention is embodied. Fig. 3 is a front elevation,
Fig. 4 a side elevation, and Fig. 5 a cross section. Similar letters refer to similar
parts in all of the figures.
Referring to Fig. 1 in explanation of the invention the winding C of the trans-
former T or the like in which it is desired to vary the number of turns, or referring
to Fig. 2 the cells C of a battery B the number in circuit of which it is desired
to vary is or are connected by wires l, to main circuit L L'; each successive
turn or coil c c¹ and so on of the winding C or each cell or group of cells c c¹ of
the battery B is connected alternately to two sets of contact pieces a a¹ respectively..
In addition to the two said sets of contacts a a¹ is arranged a pair of contact
bars AA of copper or good conducting material; a pair of contact brushes P P
making double contact between said bars and said contacts respectively is mechani-
cally passed over the said lines of contacts a, a', and according to position determines
the number of turns or cells in circuit; the two sets of contacts a al are connected
in the case of a transformer, reactance coil and other alternate current apparatus
through a stationary reactance coil or resistance R at which the line connection /
terminates; for continuous current apparatus a resistance alone would be suitable.
Describing now the special construction of electrical switch-gear illustrated in
Figs. 2, 3 and 4 upon a bed E of insulating material are fixed preferably in two
straight parallel lines the copper bars A A¹ and the two sets of electrical contact
blocks aa which latter are respectively and alternately connected to each
successive turn or coil of the winding of the instrument or to the cells of the battery
the power of which it is desired to vary; and these blocks are suitably insulated from
each other. The two bars A A' are connected at one end to a stationary reactance

page_text: coil as diagrammatically shown at R or as above stated it may be an ordinary
resistance coil. Over the two lines A a and A a and in contact therewith are
arranged, the two travelling contact brushes P P mounted on springs and con-
structed as well shown in Figs. 2 and 3. The pair is fixed to and insulated from
a bridge piece D having a female nut d. The whole is travelled to and fro by a
screw S preferably with triple thread and carried in bearings ss and operated by
a hand wheel H as illustrated,or, otherwise, conveniently. As an additional safe
guard against accidental shocks to the operator an insulated coupling with ebonite
washers ii is shown as provided. It will be seen that the two bars A A¹ being
only in conductive connection with each other through the reactance or resistance R
the latter therefore serves to prevent short circuiting of the turn or coil or cell at
the recurring instants when both branches are in contact with the respective con-
tact pieces a a¹, and thus the flow of current at such moments is limited to any
desired amount by suitably proportioning the reactance or resistance. All details
are well shown in the figures..
-
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :-
1. The improved means for changing the number of active turns in either of
the coils of a tansformer or in a reactance coil or for varying the number of active
cells of a storage battery consisting in the arrangement and use in combination
with two lines of contacts each successively and alternately connected with the
turns of winding or cells of the battery in which variation is required and two
contact bars and two travelling contact brushes adapted to make contact between
same, of a stationary reactance or resistance connected to said contact bars and to
line, whereby excessive current is avoided during operation as set forth.
2. The arrangement and combination of parts embodying the invention referred
to in the preceding claim and constituting the improved switching gear described
in reference to and illustrated in Figs. 3, 4 and 5 of the accompanying drawings,
for the purpose set forth.
Dated the 11th day of November 1897.
For the Applicants,
J. C. CHAPMAN,
Chartered Patent Agent, 70, Chancery Lane, London, W.C.