Improvements in Electrical Switch Apparatus.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electrical Switch Apparatus.
I, THOMAS HERBERT MINSHALL, of the Electric Light Station, Croydon, in the
County of Surrey, Electrical Engineer, do hereby declare the nature of this inven-
tion to be as follows:-
My invention relates to a construction of electrical switch apparatus, more parti-
cularly for currents of high potential, in which on the one hand a switch provided
with two contact plugs that are removed from both fixed contacts when the cir-
cuit has to be broken, is so arranged that it can either be turned on a pivot to
which it remains attached on breaking or closing the circuit, or it can be detached
from its pivot and be entirely removed when required. Secondly, I provide at
the fixed contact connected with the feeding circuit a shutter enclosing the said
contact when the switch plug is withdrawn, and which is so constructed that when
the switch is moved towards the contact it automatically opens the shutter so as
to allow the switch plug to enter the contact, instead of the shutter requiring to
be opened indirectly by levers or other means as is the case with shutter apparatus
of present construction.
For these purposes I construct the said switch apparatus as follows:-I construct
the moveable switch as a plate of vulcanite or other suitable insulating material
with a handle preferably of looped form at the back, and having at each end a
plug of conducting material fixed therein, the two plugs being preferably con-
nected by a strip of lead or other easily fusible metal, so that the switch also
operates as a safety fuse; they may however be connected by a permanent con-
ductor. The one plug of the switch has an enlargement on the outer side, to
which are fixed laterally projecting pivot pins, and immediately beyond the cor-
responding fixed contact is provided a double bracket having two slots into which
the pivot-pins of the switch can be slid, so that the bracket constitutes bearings
for the pivots of the switch, when turning this in one direction or the other for
causing its plugs either to enter the fixed contacts (which may be of any suitable
known construction) or to be withdrawn therefrom.
On the bracket is provided a sliding guard which is caused either by gravity
or by a spring to slide across the slots of the bracket, so as to retain the switch-
pivots therein when they have been inserted.
This slide is provided with inclines on its front side so that when the pivots are
pushed against them in being inserted into the slots, the slide will be automatically
moved from in front of the slots, so as to allow the pivots to pass in.
The slide also has on its inner side a shoulder projecting over the one pivot
pin of the switch when inserted in the slot, and the latter has its inner end made
somewhat wider in an upward direction than the diameter of the pivot.
Thus when it is desired to remove the switch entirely from its attachment, this
can be easily effected by slightly canting its one side upward, whereby the said
pivot pin, in bearing against the shoulder of the slide, will raise this up sufficiently
to allow the pivots to be withdrawn from the slots.

page_text: For enabling the other plug of the switch to effect the opening of the shutter
automatically on being inserted into its fixed contact as described, I construct a
shutter of a plate of vulcanite or other suitable insulating material, which is
pivcted to the base of the contact at a point some distance below the latter; and
it is so formed as to extend up in front of the contact so as to enclose the same
entirely when the switch plug is not inserted, the shutter being held in that
position by suitable springs or balance weights.
.
Projecting from the upper edge of the shutter, a downwardly curved lip pro-
jects forward to such an extent that when the switch is being turned into its clos-
ing position, the upper stud will bear against the said lip of the shutter in such
a manner as to turn this downward on its hinge so as to uncover the contact and
allow the plug to enter it.
Instead of arranging the shutter to open downward as described, it may also be
arranged to open in a lateral direction; also, instead of having only a single
shutter, this may be formed into two half shutters, meeting together with their
curved lips, and opening in opposite directions when the plug is inserted.
It will be obvious that the above construction of shutter may also be used with
contacts for plug switches arranged differently from that above described.
Dated this 15th day of February 1898.
ABEL & IMRAY,
Agents for the Applicant.
I, THOMAS HERBERT MINSHALL, of the Electric Light Station, Croydon, in the
County of Surrey, Electrical Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement:-
My invention relates to a construction of electrical switch apparatus, more parti-
cularly for currents of high potential, in which, on the one hand, a switch provided
with two contact plugs that are removed from both fixed contacts when the cir-
cuit has to be broken, is so arranged that it can either be turned on a pivot to
which it remains attached on breaking or closing the circuit, or it can be detached
from its pivot and be entirely removed when required. Secondly, I provide at
the fixed contact connected with the feeding circuit a shutter enclosing the said
contact when the switch plug is withdrawn, and which is so constructed that when
the switch is moved towards the contact it automatically opens the shutter so as
to allow the switch plug to enter the contact, instead of the shutter requiring to
be opened indirectly by levers or other. means as is the case with shutter apparatus
of present construction.
For these purposes I construct the said switch apparatus as I shall describe
referring to the accompanying drawings. Fig. 1 is a vertical section through the
middle, and Fig. 2 is a section at the side of the middle.
A is the moveable switch made of vulcanite or other suitable insulating materia!
preferably, as shewn with a handle of looped form at the back, and having fixed
at its ends plugs B and of conducting material, the two plugs being preferably
connected by a strip F of lead or other easily fusible metal, so that the switch
also operates as a safety fuse; the plugs may however be connected by a permanent
conductor.
The one plug C of the switch has an enlargement on the outer side, to which
are fixed laterally projecting pivot pins c, and immediately beyond the correspond.
14

page_text: ing fixed contact is provided a double bracket E having slots into
which the pivot pins c can be slid, so that the bracket E constitutes bearings
for the pivots c, when turning this in one direction or the other for causing its
plugs B and C either to enter the fixed contacts 1), (which may be of any suitable
known construction) or to be withdrawn therefrom.
On the bracket is provided a sliding guard G in the form of a yoke which is
caused either by gravity or by a spring to slide across the slots of the bracket E
so as to retain the pivots c therein when they have been inserted.
This slide is provided with inclines on its front side so that when the pivots c
are pushed against them, in being inserted into the slots, the slide is automatically
raised from fronting the slots and allows the pivots e to pass in.
The switch has pivotted on its lower part a piece a which in its normal position
meeting the base as shewn in full lines in Fig. 2 forms a stop preventing the
switch from being turned farther on its pivots c.
But on turning the piece on its pivot so as to stand at right angles as indicated
by the dotted lines a¹ the switch can be turned farther down.
By this farther movement the nose N of the switch plug C comes to act on the
slope g of the guard G and raises the guard so that it leaves the pivot to pass
out of the slots of E when the switch can be pulled quite away.
The upper contact D is in a chamber covered in front by a pivotted shutter $
urged by a pair of springs to close the front when the plug B is withdrawn. The
shutter S is made of vulcanite or other suitable insulating material with a curved
limb s projecting forwards and downwards, so that in pushing forward the plug B
its nose 6 acts on s pushing it down and opening the shutter for its admission.
The nose is faced with vulcanite or like material so that as it slides over the
face of s no metal streak is left thereon.
The shutter instead of being single as shewn might be made in two parts, one
pivotted below and the other pivotted above the front of the contact, or the two
parts might be pivotted at the sides, the nose b being suitably shaped to open them
apart when it is pushed in between inclined lips projecting from them.
The sides X, ends Y and back Z are mad of strong insulating material such for
instance as marble, or other stone or ceramic material.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed I declare that what I claim is:-
1. An electrical switch constructed and operating substantially as described
with reference to the drawings.
2. In combination with one of the contacts, a spring shutter having a curved
limb arranged in relation to the switch, so that the shutter is opened by the closing
movement of the switch, substantially as described.
Dated this 27th day of June 1898.
ABEL & IMRAY,
Agents for the Applicant.