Improvements in Electrical Switches.
Year: 1898

page_text: Improvements in Electrical Switches.
VERITYS LTD., Electrical Engineers, of Plume Works, Aston, Birmingham,
in the County of Warwick, and LOUIS JOIN STEELE, Electrical Engineer, of 14,
Clarendon Road, Holland Park, London, W., do hereby declare the nature of
this invention to be as follows:
"
In electric switches specially adapted for breaking high tension currents, it is
necessary that not only should the are be quickly and effectively broken to prevent
a continued passage of current, but also that the risk of personal contact with any
live part should be minimized as much as possible. Attempts have been made
to apply screens or shutters to switches for this purpose, but the systems hitherto
devised have proved complicated, expensive, and bulky. The switch according to
our invention is characterized by the use of one or more shutters or screens of
mcombustible non-conducting material caused to move in such a position by the
action of the switch, that the continued passage of current due to an are is pre-
vented, and the switch contacts protected. In some cases two shutters or screens
are caused to work in opposite directions in order to produce a still quicker
disruptive effect, and higher resistance. In one form of switch made according to
our invention we employ a quick break type, preferably operated by a spring, and
locked when in its on position, and provided with an adjustable stop or
trigger, the use of which is to release the switch at the right moment, to take up
any wear which may take place in the locking device, and also to act as a stop
to the switch when in its off" position. The contacts to which the circuit is
connected may be placed at either the back or front of the switch-board, or insulating
slab, on which the switch is mounted, or between the switchboard and insulating
slab. The switch arm may operate at the back or front of the slab; when placed
in front holes or slots may be provided in the slab to allow the switch arm to make
contact to the terminals by means of a metallic piece suitably insulated from the
switch arm and protected when in its position, means being also provided
for operating the above mentioned screen or shutter. According to one form of
our invention the switch arm is provided with an arrangement of radial arm and
links or levers or an equivalent device, such that the quick motion of the switch
arm is simultaneously imparted to the insulating screen or shutter. This may
be likewise placed at either the front or back of the slab or switchboard, its motion
if necessary checked by the use of a spring, dash-pot, or equivalent device. The
screen or shutter in some cases we provide with a weight or spring which is auto-
matically released by the action of the switch, causing the shutter to operate as
on

page_text: before stated. In some cases the insulated slab is mounted on a supporting frame
and so hinged that the parts at the back are accessible for inspection or cleaning.
Dated this 12th day of July 1898.
LOUIS J. STEELE.
VERITYS LIMITED,
GEO. H. VERITY,
Director,
improvements in Electrical Switches.
We, VERITYS LIMITED, Electrical Engineers, of Plume Works, Aston, in the
County of Warwick, and Louis JOHN STEELE, Electrical Engineer, of 14, Clarendon
Road, Holland Park, London, W., 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 relates to electrical switches, and particularly to those used in
circuits of high tension, and has for its object certain improvements hereinafter
described and claimed for quickly and effectively preventing the continued passage
of the current between the switch terminals when the said current has been broken
by the off operation of the switch, and for minimising as much as possible
the risk of personal contact with any live part in the circuit; the chief idea being
to obtain a quick disruptive effect.
"
"
The improvements according to this invention are characterised by the use in
connection with an electric switch of one or more movable shutters or screens of
incombustible non-conducting material, such as micanite which is, or are, caused
to move at right angles to the line of formation of are into such a position or
positions by the ordinary operation of a switch into an off position, so that the
continued passage of the current between the terminals and contacts due to an
are is prevented, any are formed broken or cut, and the said contacts terminals,
and switch board protected; the said shutter or shutters being again moved out
of their active position or positions by the action of operating the switch into an
on" position.
..
A high tension wall-switch of a quick-break type and constructed and fitted with
improvements according to this invention is illustrated in the accompanying sheet
of drawings; Fig. I being a front elevation thereof with the operating handle cut
away; Fig. 2 a back elevation; Fig. 3a vertical section with parts in elevation in
an on position; Fig. 4 a like vertical section in an "off" position, and Fig.
a diagramatic plan of the contact pieces of the switch and their carrying means.
In these figs. a single acting screen or shutter is used for producing the desired
disruptive effect, but in Fig. Ca method of applying two of such shutters or screens
to a switch is diagramatically shown.
The invention will now be particularly described in connection with the said figs.
In Figs. 1 to 4 a is the switch board or carrier upon which is hingedly mounted
at, by means of a suitable bracket, the switch arm c carrying the contact
pieces, the said pieces being arranged upon a non-conducting sheath carried
upon the switch arm's free end, so that they are insulated from the said arm. The

page_text: on
switch arm c is spring-controlled when breaking circuit, and is locked in an
position, and freed from that position, by well-known devices which are connected
with the said switch arm, switch board, and operating handle e; the said locking
and releasing devices having formed in conjunction therewith an adjustable stop di,
carried upon the operating handle e, by which the releasing of the switch arm
can be adjusted to the right moment and any wear in the lock device compensated
for.
The switch board or carrier a, which may be of any suitable material, has the
circuit terminals d, &, connected to its back face so that the yielding tips d' thereof
come opposite slots or openings formed through the switch board to admit of
the passage of the contact pieces * to engage the said tips when the switch is
65
on.
33
Working up and down against the back face of the switch board so as to disrupt
or cut any are vertically to its line of formation is a shutter or screen g of an
incombustible non-conducting material such as micanite, the said shutter being
of a sufficient length and breadth to embrace both openings in the switch board
when in position over them and to form a closure thereto. This shutter is carried by
means of a bracket 2 upon a guide rod rigidly connected to the switch board,
and slides up and down thereon so as to close and open the slots d' from the back
side when the switch is respectively "off" and "on," the movement of the said
shutter being controlled from the switch arm e by means of a link and a radial
arm, which are so connected that the latter moves through an opening in the
switch board and communicates the switch arm's movement to the said link. The
connection means between the shutter and the switch arm c is such that
the quick motion of the switch arm is at a determined time communicated to the
shutter, in a manner giving the said shutter sufficient movement to clear the
slots before the free ends of the contact pieces protrude when putting the
switch on," and also such that the said contact pieces move in advance of
the shutter when the switch flies "off," it being understood that the shutter is so
timed in its movement in respect of the contact pieces as to either close the slots,
as aforesaid, instantly the ends of the contact pieces are withdrawn from the slots
or after the arc has been somewhat drawn out, so that if such an arc is formed
between the terminals and the contact pieces it is at a predetermined time disrupted
or broken. From practice it is found best to draw out the are somewhat before
the shutter moves into position.
In Fig. 6 two over-lapping shutters or screens g, m, are employed, one moving
upwardly and the other downwardly, so as to close the slots d; their movement
being preferably controlled by the switch arm before described. In such an
arrangement the disruptive effect produced would be much quicker than were a
single shutter only is employed, as the slots in such a case would be fully closed
immediately the shutters moved half way across them.
In Fig. 7 a diagramatic view illustrates a shutter operated automatically from
the switch arm but rotating or turning in its movement instead of sliding. This
rotating shutter is timed in its movement in respect of the contact pieces in any
convenient manner, and its working is identical with the one previously described.
The rod connects it through the link to a part on the switch arm, not shown.
Fig. 8 shows two of such rotating shutters coupled so as to work together, and
it will be obvious from the slots o provided in them, and also in the shutter Fig. 7,
how an adjustment as to the throw for rotating them can be effected.
Instead of the shutters or screens being connected to the switch arm and
traversed by its actual movement they may be disconnected from the switch arm
and connected with spring or weights, which are arranged so as to operate them
at predetermined times, in which case a part upon the switch arm may be brought
into action as a means for releasing the said springs or weights so that they
become operative. For example, in the arrangement of shutter Figs. 1 to 4 a
compressed spring could be arranged at the back of the shutter g so as to, when
the shutter is free to move, traverse it into the position shown in Fig. 4, the said

page_text: shutter being held back against the power of the spring when in the position
shown in Fig. 3 by a short projection or equivalent device upon the switch arm
which would be arranged to engage it at a required time. In this case an inde-
pendent movement of the handle e in respect of the switch arm could, when the
switch is being put on, force back the shutter and compress the spring prior to the
contact pieces passing through the holes d'
In Fig. 3 is shown in dotted lines an arrangement of switch board in which the
terminals of the circuit are carried upon an insulating slab o, the switch board
being formed with sides o² and hinged to the said slab at o³, so that the switch,
minus the terminals, can be hinged away to obtain access to the parts at the back
for inspection or for cleaning purposes.
The movement of the shutters or screens may be steadied by the use of a dash
pot or similar cushioning device.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:-
First. In an electric switch, the use of a moving screen or shutter automatically
operated, either directly or indirectly by the movement of the quick break switch
arm, or its operating mechanism, so as to cut or break the arc at right angles to
its line of formation at a determined time in respect of the terminals and contact
pieces separating, and move into and out of position between the terminals of the
circuit and the contact pieces, substantially as described.
Second. In an electric switch, the combination of a switch board carrying circuit
terminals, a switch mounted thereon so that its contacts are adapted to engage the
said terminals, and a screen or shutter automatically operated by said switch
and carried upon the switch board, and which is adapted to be worked in con-
junction with the movement of the switch arm so as to cut any are formed between
the terminals and contact pieces vertically to its line of formation, substantially
as described.
Third. In an electric switch, the combination of a switch board a having open-
ings and within it, circuit terminals d, d, located and fixed at the back of
the said board, a quick-break switch arme carrying contact pieces and, in some
cases, fitted with locking and releasing mechanism, and a shutter or screen g
mounted on the switch board to open and close the holes, and which is worked
off the switch arm e by arms, links, and levers so as to disrupt any are at right
angles to its line of formation, substantially as described.
Fourth. In an electric switch, the general arrangement and combination of the
parts to operate in the manner described in Figs. 1 to 4.
Fifth. In an electric switch of the kind hercinbefore claimed, operating the
shutter or shutters by springs or weights, which are released by the action of
the switch arm substantially as described.
Sixth. The general arrangement and working of the compound shutter or
screen g, m, as set forth in Fig. 6.
W. P. THOMPSON & Co..
11, Burlington Chambers, New Street, Birmingham,
Patent Agents for the Applicants.