Improvements in Automatic Electric Switches, and in their Use for Distribution of Electricity.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Automatic Electric Switches, and in their Use for
Distribution of Electricity.
I, JOHN HOPKINSON F.R.S. of 5 Victoria Street London, S.W., Civil Engineer,
do hereby declare the uature of this invention to be as follows:-
My invention relates to the class of switch which forms the subject of my
Patent No. 22,876 of 1893, to which I hereby refer. It is addressed to rendering
switches more adequate for use for the distribution of electricity from central
Sources of supply. Parts of my invention are also applicable to other electrical
automatic devices.
In a switch which has to be actuated automatically it is desirable that the
pressure of the contacts shall be as light as is possible consistently with certainty
of contact and be known in amount. This I found it couvenient to secure by
making a contact piece in the form of a lever freely pivoted on a fulcrum carried
by a shaft which is forced up to its work by a spring or weight. This ensures that
the pressure on the two contacts shall have a definite value and be divided between
theni in a definite proportion.
n
According to my present invention for large currents I use a contact piece in
halves and I divide the pressure on the contact piece firstly between the halves,
secondly between the two contacts of each half.
When many switches are combined upon a switchboard it is more convenient to
ariange the contacts in line with each other instead of dial fashion. In this case
I make use of contact pieces in pairs forcing them up to each other by means
of springs, in this way realizing the same idea of equally dividing the pressure
between the different contacts and securing that there is an adequate pressure upon
each
In this case the contacts may be diawn along the bars by means of a chain
actuated by a sprocket wheel and the connections to the battery cau be made by
means of copper strips running perpendicular to the bais aud secured to sections of
the bars. The divided bar may have the form of a central rod on which are placed
an insulating tube or insulating thumbles and on this insulating tube or insulating
thimbles, metallic thimbles for making the several contacts to the battery.
In switches for charging batteries I find that it is better to make use of a small
and separate switch for the purpose of connecting the automatic apparatus to the
Buccessive cells of the battery instead of making the contacts of these successive
cells by meaus of the main switch.
According to my present invention I may make use of an electromagnet or
electromagnets the wire of which 18 connected to the terminals the difference
of potential between which determines the motion of the switch. I so construct the
electromagnet that its equilibrium when resting against a stop is essentially
unstable, that is so that when once it bogina to move it moves with considerable
energy to a position in which it makes a contact of considerable firmness in another
circuit, if used as a relay. If working direct it acts with considerable energy for
the purpose of releasing the brake and permitting the apparatus to move
Preset
the electromagnet by the movement of parts connected to the switch actuated by the

page_text: agency of the electromagnet. I either short circuit the electromagnet or break its
circuit or increase the resistance of its circuit if the electromagnet is to operate
when a rising pressure attains a standard value, or if the electromagnet is to
operate when a falling potential reaches a standard value I diminish the resistance
of the electromagnet circuit or in some way increase the current though it, also by
the movement of parts connected to the switch. In this way cause the switch to
move one step ouly and a complete step in the desired direction and reset the
electromagnet ready to take the next step when the proper time alives
circuit which is made by the action of the electromagnet may lead through
the armature of a dynamo machine oi may lead through an electromagnet which
releases a catch or brake and per inits the switch to move under the action of a weight
or spring.
The
In the case of the discharging switch it is necessary to secure that the two
electromagnets used for actuating the mechanisin shall not give contradictory
signals This I accomplish in one or other of two wayɛ. either interlock their
armatures mechanically so that both armatures cannot operate simultaneously or if
the electromagnets are of the nature of relays I may take the current made by one
round the other electromagnet in such wise as by mcreasing or diminishing its
attiaction to prevent its armatures from operating Instruments of the class herein
described are peculiarly sensitive to vibration. I avoid the effect of mechanical
vibration by attaching to the insti unients a suitable weight and carrying the whole
upon springs.
I find that in some cases it is beneficial to carry the armatures of the electro-
maguets upon geometrical supports for example I dehne three degrees of constraint
by allowing a cone to rest upon a point, two more degices of constraint by a groove
resting upon a point, a sixth degree of constraint by a surface resting upon a point.
In the case when the electromagnet acts mechanically and not as a relay I cause the
atmature on lifting through a certam defimte space to come in contact with an aim
which takes off the bike and allows the apparatus to move As the apparatus
moves a cam lifts the arm through a further space and removes it from contact with
the armature.
The methods herein indicated for actuating automatic switches for batteries are
capable of wide application They may be used for determining the motion of
cai bons in arc lamps, for the resistance coils introduced into the magnets of
continuous and alternating current machines for the purpose of giving a constant
current on constant potential.
Dated the 10th dox of Nov 1805
Improvements in Automatic Electric Switches, and in their Use for
Distribution of Electricity.
I, JOHN HOPKINSON, F.R.S., of Westminster Chambers, 5 Victoria Street,
London, S. 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 :-
My invention relates to the class of switch which forms the subject of my
Patents Nos. 22,876 of 1893 and 2064 of 1895 to which I hereby refer. It is
addressed to rendering the switches more adequate for use for the distribution of
electricity from central sources of supply. Parts of my invention are also
applicable to other electrical automatic devices.
In a switch which has to be actuated automatically, it is desirable that the
pressure of the contacts shall be as light as is possible consistently with certainty

page_text: of contact and be known in amount. This found it couvenient to secure by
making a contact piece in the form of a levet freely pivoted on a fulcrum carried
by a shaft which is forced up to its work by a spring or weight. This ensures that
the pressure on the two contacts shall have a definite value and be divided between
them in a definite proportion.
According to my piesent invention for large currents I use a contact piece in
halves and I divide the pressure on the contact piece firstly between the halves,
secondly between the two contacts of each half.
When many switches are combined upon a switchboard it is more convenient to
In this case
arrange the contacts in line with each other instead of dial fashion.
I make use of contact pieces in pairs forcing them up to each other by means
of springs, in this way realizing the same idea of equally dividing the pressure
between the different contacts and securing that there is an adequate pressure upon
each. In this case the contacts may be diawn along the bats by means of a chain
actuated by a sprocket wheel and the connections to the battery can be made by
means of copper stups running perpendicular to the bars and securel to sections of
the bars The divided bar may have the form of a central iod on which are placed
an insulating tubo or insulating thimbles and on this insulating tube or insulating
thumbles, metallic thumbles for making the several contacts to the battery.
In switches for charging batteries I find that it is better to make use of a small
and separate switch for the purpose of connecting the automatic apparatus to the
successive cells of the battery instead of making the contacts of these successive
cells by means of the main switch.
According to my present invention I may make use of au electromagnet or
electromagnets the wire of which 18 connected to the terminals the difference
of potential between which detei mines the motion of the switch
I leget
I so construct the
electromagnet that its equilibrium when resting against a stop is essentially
unstable, that 19, 80 that when once it begins to move it moves with considerable
energy to a position in which it makes a contact of considerable firmness in anothe
circuit, if used as a relay If working direct it acts with considerable energy for
the purpose of releasing the brake and permitting the apparatus to move
the electromagnet by the movement of paits connected to the switch actuated by the
agency of the electromagnet. 1 cither short circuit the electromagnet or bicak its
circuit o melease the resistance of its cn cut if the electromaguet is to operate
when a rising pressure attains a standard value, or if the electiomagnet is to
operate when a falling potential reaches a standard value I diminish the resistance
of the electromagnet circuit or in some way increase the curent through it, also
by the movement of paits connected to the switch In this way I cause tho switch
to move one step only and one complete step in the desired duection and reset the
electromagnet ready to take the next step when the proper time arrives
circuit which is made by the action of the electromagnet may lead through
an electromagnet which ieleases a catch or brake and permits the switch to move
under the action of a weight or spring.
The
In the case of the discharging switch it is necessary to secure that the two
electromagnets used for actuating the mechanism shall not give contradictory
signals This accomplish in one or other of two ways. I either interlock thei
armatmes mechanically so that both aimatues cannot operate simultaneously or if
the electromagnets are of the nature of clays I may take the current made by one
1ound the other electromagnet in such wise as by increasing or diminishing
its attraction to prevent its armature from operating. Instruments of the class
herein described ate peculiarly sensitive to vibration. I avoid the effect of
mechameal vibration by attaching to the instruments a suitable weight and carrying
the whole upon springs
I find that in some cases it is beneficial to carry the armatue of the electio-
magnets upon geometrical supports, for example I define three degrees of coustiaint
by allowing a cone to rest upon a point, two more degrees of constraint by a groove
resting upon a point, a sixth degree of constraint by a surface resting upon a point.

page_text: In the case when the electromagnet acts mechanically and not as a clay I cause
the armature on lifting through a certain definite space to come in contact with an
arm which takes off the brake and allows the apparatus to move As the apparatus
moves a cam lifts the arm through a further space and removes it from contact with
the armature The methods herem described for actuating automatic switches for
batteries are capable of wide application They may be used for determining the
motion of carbons in are lamps, for the resistance coils introduced into the magnets
of continuous and alternating current machines for the purpose of giving a constant
current or constant potential.
Figs. 1, 2, 3, 4, 5 & 6 illustrate my invention as applied to a charging switch for
large culents The contact piece or arm A is made in two parts which are
carried heely upon a spindle B from a crosshead C which is in turn carried by a
pin D passing loosely through a head E securely attached to the shaft F. The
pressure of the two parts of the arms A up in the contact pieces 1, 1, 2, 2*, &c. and
upon the ring 17 is obtained by a spung G and is adjustable by nuts II. By the
above arrangement I am able to secme that the pressure of the four ends of the
arms A upon the contact pieces shall be equal and determinato tu amount
The shaft F cartes a wheel through which the switch is actuated by a weight.
Upon the shaft F is a spur wheel K which drives though a pinion La shaft M
upon which is a spur wheel N diving through a pinion O a shaft, l' On the
shalt M is a wheel R in the periphery of which is a slot X and upon the shaft P
12 a brake wheel Q The armature T of the electromagnet S (Fig. 4) operates
upon one arm of a bell crank lever U whose other aim cairies a brake block W
and detent Y
In switches for charging batteries I find it is better to make use of a small and
separate switch for the purpose of connecting the automatic apparatus to the
successive cells instead of making the contacts of these successive cells by means
of the main switch.
The
In Figs 2 & 3 have shewn a subsidiary switch consisting of two insulated
alms 34 & 35 carried from the shaft and making contact with a series of contact
pieces 18, 19. 20 &c. connected to the end cells which are being changed
arms are attached to insulated ungs 36, 37, in contact with which are two bushes
connected to terminals 38, 39 which are in turn connected to the magnet S Figs 4
& 5 or to a clay
The operation 18 as follows,-When the cell connected between the contact
pieces upon which the arms 34, 35 rest is fully changed the magnet S attracts the
armature T and through the crauk U V draws the brake block W from the
wheel Q and the detent Y from the slot X of the wheel R thus allowing the weight
to move the aims A to cut out the cell To ensure that the arms shall not rest in
an intermediate position the brake W can only act on the wheel Q when the
detent Y has entered the slot X and thus can only ocem when the aims are in
proper position.
A secondary contact arm A' of considerable resistance is connected to the arm A
to prevent the cells being short cncuted as the am A passes from one contact
piece to the next and to maintain a path for the current during such movement
The regulation of the switch is shewn in Fig: 4 & 5 The end of the bell
cranh lever V 15 indicated by U S is an electiomagnet carted on a sping or
springs for the purpose of preventing the action of the electromagnet from being
disturbed by mechanical vibiation The armature T of the electromagnet iests
when not in action against three pointed screws 41, 12 & 43, the aimatie being
provided with a cone and a V shaped lot and a plane surface as shown in Fig. 6
for the points of the said screws to bear øgainst The cone rests on the point of
one of the screws, the slot rests against the point of another of the screws, whilst a
plane sui face also on the underside of the aimature rests against the point of the
third scien. Three suitably arranged V shaped slots will also answer In this
way secure that the armature when not in operation shall always occupy the
same position in relation to the magnets The coils of the electiomagnets are

page_text: connected to the springs 38 & 39 (Figs. 2 & 3) and so to the cell of the battery
which is to be next out out. It will be observed that the armature T when not in
action does not touch the end U of the bell cıank lever.
The action of the instrument is as follows -Suppose the battery consists of
sixty cells and that the charging machine is connected directly to the first cell and
through the switch to the 55th. Thus 55 cells will be undergoing charge and the
55th cell will be the next to be cut out The two arms 34 & 35 of the small
switch will be connected respectively to the junctions of the 55th & 56th colls.
Thus the electromagnet will be excited by the potential of the 56th cell. The
screws 41, 42 & 43 and the resistance of the electromagnet circuit are so adjusted
that when the potential of the electromagnet reaches, let us say, 2.6 volts, the
force of the magnet becomes equal to the weight of the amature. The armature
then uses.
At first it moves absolutely freely and the force of the magnet
increases on account of the approach of the armature to its poles. The armature
theu impinges on the end U of the bell crank lever and lifts the biake block W off
the brake wheel Q and moves the projection Y from the recess X The weight
on the chain passing over the wheel K now turns the switch and the cam wheel R
prevents the brake from stopping the movement until the step 19 completed when
the projection Y enters the recess X or next succeeding recess The small switch
Fig. 3 as it moves breaks the circuit of the electromagnet and allows the armature T
to drop and so resets the aimature ready to operate to cut out the next cell when
its potential in tuu reaches 2'6 volts When the step of the main switch 14 com-
pleted the point Y of the lever V drops into the recess X and allows the biake.
block W to operate on the biake wheel Q and stop further motion
It is clear that my invention may be applied in other ways by varying the minori
details. For example, instead of diving the switch by a weight it may be driven
by a small dynamo machine the armature of which is either upon the shaft Po
geared therewith. In this case the lever V U mstead of carrying a biake block
makes a contact and causes a current to pass through the amature of the small
machine when the lover V U is operated by the action of the electromagnet S In
this case it is possible if preferred to dispense with the cam wheel R and to rely
upon the momentum of the small dynamo armature to carry the switch over the
point where the circuit of the electromaguet is broken.
In Fig 7 I have shown an arrangement of electromagnets suitable for a
discharging switch actuated by an electromotor. The points A, B, represent
terminals between which the potential is to be regulated. The electromagnet C
determines the action of the switch when uumber of cells is to be increased, on
account of the potential of the battery becoming too low. The electromagnet D
deteimmes the action of the switch when the number of cells is to be decreased on.
account of the potential of the battery becoming too high.
Refering to the electromagnet Cit is clear that when the attraction of the
imagnet diminishes to a pomt at which the armature leaves points of support that
the attraction of the magnet for the armature will greatly diminish as the armature
becomes more moved from the magnet and that therefore when the amature drops
down upon the contact screws it will make a good electrical contact between
the two screws
The screws H 1 are connected with the armnature of the motor
machine and with one or more cells of a battery Q in such wise that when contact
is made between them, the armature of the electromotor will revolve in one dnec-
tion. The conesponding screws II of the other electromagnet are connected with
the armature of the motor and with other cells R of the battery in such wise that
when contact is made between them the armature will revolve in the other direction.
Que of these two chcuits say that of the electromagnet C 18 carried round the other
electromagnet by a supplementary coil S so that if the electromagnet C operates
the magnetism of the electiomagnet D 1 diminished by a current circulating
though the supplementary coil S and it is thereby secured that if the electro-
magnet C is operating the electromaguet D cannot operate until the operation of
the electromagnet C is completed.

page_text: The main coils of the electromagnets C & D are normally connected to the
terminals of the main conductors of supply A & B, but they are so connected
through the switch K which inoves with the main switch which it is the intention
of the apparatus to opeinto. This switch K has bearing upon it three contacts L
M N and in turning it moves through a complete period of its changes when the
main switch advances by a complete step The shaded parts of the switch K
indicate insulating material, the non-shaded parts indicate conducting material
If the main switch moves in a direction to diminish the number of cells connected,
the switch K moves in the direction indicated by the arrow.
When the number of cells becomes too great, the armature F of the electro-
inagnet D will rise, will make contact between the screws II and the main switch
will move in a duection to diminish the number of cells When its motion is
nearly completed the conducting parit O short circuits the contact pieces M N the
electromagnet D will thus be short circuited and the amature F will drop into its
normal position ready to give or refuse to give a further signal as may be required.
On the other hand if the number of cells becomes too few, the armature F of the
electromagnet C will fall and will make contact between the screws II and II: a
current will then pass and will cause the main switch to operate Near the end of
the time of its operation the contact pieces L M of the switch K will be short
circuited and will so short circuit the resistance rand increase the current through
the coils of the electromagnet C thereby causing the armate F of this electio-
magnet to be raised into its normal position.
It is obvious that the details of this apparatus may be vailed. The conducting
part may be replaced by an insulating part which shall have the effect of
breaking the cn cut of the electromagnet D instead of short cu cuiting it.
The electromagnets C & D are freely suspended by springs 7 and are made with
massive yokes whereby being insensitive to mechanical vibration.
Figs. 8 & 9 show an alternative mangement of the electiomagnets. The
armatures F of the electromagnets C & D nie carried on arms A & J and the
relays are interlocked by a part of the aim J overlapping part of the aim A
thereby cusuring that the amature of the magnet C shall not fall unless the
armature of the magnet D has also fallen.
In Figs. 10, 11, 12, 13 14 I have shewn switches made with contact bars
arranged vertically
The batteries are connected to copper strips A which are in turn connected to
tuetallic thimbles B forming a divided bai. The thimbles are insulated from each
other and are caned upon insulating thimbles or iods C from a metal bar D
supported in brackets E. The contact pieces are arranged in pairs FF and aro
pressed against the divided bar and the contact bai G by spings II the pressure
being adjustable by nuts I. Each contact piece thus has a fulcium at the point of
application of the force of the spring. A pan of subsidiary contact pieces J
connects the divided bai to a metal bai K between which and the bar Ga
resistance is inter posed thereby preventing the circuit being opened on the cell
being short cucuited, as the contact pieces FF pass from one thimble to the next.
The contact pieces are attached to, but insulated from a cham M, passing
round a sprocket wheel N. In the airangement shown in Figures 10 & 11 the
sprocket wheel N is driven by an electric motor O the arrangement being suitable
for a discharging switch. Although in the figures the bars are shown vertically
they may be arranged horizontally.
The switches may be placed side by side the corresponding thunbles of the
several switches being connected to one copper stup A.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim 18
1st. A switch of lial form in which the pressure of a swindle is firstly divided

page_text: between two contact pieces and then again divided between the two contacts of
each contact piece substantially as and for the purpose herein before described.
2nd. A straight switch in which tho movable contact pieces or levers F Fare
aLanged on opposite sides of the bars B G and are forced towards each other by a
spring, the contact pieces or levers F F having their fulcrum at the point of
application of the sping nirauged substantially as and for the purpose hereinbefore
descubed.
3rd. In an automatic battery charging switch the use of an auxiliary switch for
making connection with the successive cells of the battery substantially as described
with reference to Fig 3.
4th. In a discharging switch the means horen described for preventing the two
relays from signalling simultaneously viz. (a) by mechanically interlocking the
armatures substantially as in Figs. 8 & 9 or (b) by electrical control of one
electromaguet on the other substantially as shewn in Fig 7.
5th. A regulating electromagnet cairied on springs substantially as shewn in
Figs. 5 & 7.
6th. A regulating electromagnet the armature of which is carried on a
geometrical support defining its precise position in relation to the electromagnet
substantially as described with reference to Fig. 6.
Dated this 29th day of January 1896.
J. HOPKINSON.