Improvements in Apparatus Employed in Regulating Electro Motive Force in Alternating Current Circuits for Theatre Lighting or other Useful Purposes.
Year: 1895

page_text: Date of Application, 9th Oct. 1895
Complete Specification Left, 3rd July, 1996-4ccepted, 8th Aug., 1896
PROVISIONAL SPECIFICATION.
Improvements in Apparatus Employed in Regulating Electro Motive
Force in Alternating Current Circuits for Theatre Lighting or
other Useful Purposes.
We, ISAAC PROBERT, of 25 Union Road, Claphum, in the County of Surrey,
Electrical Engineer, and ERNEST FRANCIS MOY, of 20 Loraine Road, Holloway,
in the County of London, Electrical Engineer, do hereby declare the nature of
this invention to be as follows:-
Our invention relates to improvements in apparatus employed in regulating the
electro motive force in alternating current circuits, for controlling the lighting of
theatres, and for other useful purposes.
In the first part of our invention we employ choking coils, but instead of the
coil winding (series) being continuous, in the usual manner, each coil is divided
into sections, and each section connected to a separate contact terminal of a
regulating switch, preferably of the circular or rotating type. Upon the axle of
the regulating switch, or regulator, is secured a bridge piece, one end bearing
continuously upon a central disc plate which forms one terminal, while the other
end during its rotary movement bears upon the successive contact terminals of the
aforesaid sections of the choking coil, and of the general terminal of the main
circuit which cuts them all out. Consequently, the regulator is adapted to switch
the choking coil int or out of circuit gradually, the amount of graduation possible
being governed by the number of sections into which the coil is divided. In
addition to the bridge piece, an ebonite or other insulating dich, carrying a
pulley, is secured to the axle, and turns with it. A brass strip is attached at one
end to the pulley in such a manner that in turning the axle of the regulator in one
direction, the brass strip is wound upon the pulley, while in turning it in the
other direction, the brass strip is unwound. At the other end of the strip the iron
core of the choking coil is suspended, so that while turning the axle and the bridge
piece over the aforesaid sectional contacts, the iron core is simultaneously raise t
into or lowered out of the interior of the choking coil. It is important to note,
however, that at the beginning of the movement which puts the first section of the
choking coil into circuit, the core is so suspended as to be out of the coil a short
distance, and it only enters the coil after one or more of the sections have been
put in circuit. By this means the potential is gradually reduced, so that a sudden
drop in the voltage or electro motive force, in the alternating current circuit under
control, is entirely avoided; thus differing from the methods hitherto employed.
Conversely, in turning the regulator in the opposite direction to unwind the strip
and lower the core, the electro motive force is gradually increased in the circuit, so
that any sudden variation in the light-so objectionable in theatres-is prevented.
The regulator is conveniently placed on the top of a choking coil, the latter
forming a base of support for it.
Several regulators with their respective coils are usually employed in the
lighting of a theatre, each controlling a separate circuit. As it is frequently
desirable to regulate two or more circuits simultaneously, while reserving the power
to regulate each circuit separately, an arrangement called a check wheel is used for
each circuit, and several check wheels, corresponding to the number of circuits to

page_text: be regulated, are mounted together upon a regulating board. Each check wheel
is secured upon one end of a short axle arranged to work horizontally in a suitable
bracket bearing, the other end having also secured to it a sanill mitre wheel.
A spring plunger pin is fitted to pass through a socket bored in the check wheel
near its periphery, and a metal dise is mounted immediately behind this so as to be
free to turn freely upon the axle. On the face of the dise, next to the check wheel,
a series of holes are drilled closely together ar.and its face to coincide in position
and diameter with the end of the spring plunger pin. so that the latter can be
sprung into the hole in line with the piu, in order to lock the two together and
communicate motion from one to the other. The periphery of the dise is cut as a
worm wheel, and it is driven by a worm mounted or eut upon a long horizontal
shaft which also carries ther driving worms to actuate a line of similar chock
wheels. By means of a handle at the end of this long shaft all the dises are
turned simultaneously, and with them all the check wheels which are connected to
the discs by means of their respective sprig plunger pins. But if any one of these
pins is disconnected from its corresponding check wheel, its circuit is unaffected by
be general regulation of the others when the long horizontal shaft is turned.
Moreover, the sand circuit may then be separately controlled by its own check
wheel, which is disconnected from the dise, in the following manner.
וי
The small mite wheel on the small axle of the check wheel gears into a err
sponding one secured upon a vertical or other shalt working in the bracket alrealy
referred to, and connected in the same or an equivalent manner to the axle of the
regulating switel. Consequently, any movement of the check wheel aforesaid is
transmitted by the gearing asl shafts to the regulator, (wherever it may be
convenient to place it), which is turned to ent in or out of action the several
sections of the choking coil, and to wind up or lower the ere, as the case may be.
In the same manner all the check wheels, which are commeted with their respective
metal dises, are caused to move simultaneously by turning the long horizontal shaft
at the regulating board; and thus the circuits controlled by them are regulatel
simultaneously. If all the lights of the theatre are arranged, for example, in
three divisions either of colour or of position in the house and all the circuits
in each division are arranged at the regulating board to be worked from one long
horizontal shaft, then the three shafts of the three divisions may be connected
together by suitable gearing and worked by one movement simultaneously.
Consequently, all the lights in the house may be raised or lowered gradually at
the same time, except those which are on circuits disconnected at the check
wheels.
We sometimes insert sectional resistances between the sueressive coatnet
terminals of the regulating switch or regulator, in which case the choking coil is
wound continously. The resistances are preferably arranged to in rease in
degree, and the switch so connected across the terminals that when the sections of
the resistances are all cut out, the choking coil is short circuited; so that
practically no current passes through it. As the sections of the resistance are
successively switched inte circuit, the current is increasingly diverted through the
coil until the resistance reaches its utmost value, when the circuit through it can
be broken and all the current passed through the choking cil; the core, mean-
while, being won d into the coil, as in the former example. The resistance should
be suitably proportioned to the coil, so that any sudden drop in the potential
difference across the circuit which is to be controlled, is avoided.
In combination with either of the foregoing arrangements, when it is desirable
to fix the core, we use an adjustable non-magnetic tabe or screen over the core, to
produce the same impedance effect that is otherwise produced by moving the core
into the coil; the uncovering of the core by the movement of the screen being
equivalent to the insertion of the core in the coil. The tube is slotted to avoid
excessive henting; and the movement of the screen is produced in the same manner
as that of moving the core, the action, however, being reversed.

page_text: The term choking coil is in common use, but it is to be understood as meaning
impedance coil.
Dated this 9th day of October 1895.
FAIRFAX & WETTER,
433 Strand, London, Agents for the Applicants.
Improvements in Apparatus Employed in Regulating Electro Motive
Force in Alternating Current Circuits for Theatre Lighting or
other Useful Purposes.
We, ISAAC PROBERT, of 25, Union Road Clapham, in the County of Surrey,
Electrical Engineer, and ERNEST FRANCIS MOY, of 20 Loraine Road, Holloway,
in the County of London, Electrical Engineer, 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:-
Our invention relates to improvements in apparatus employed in regulating the
electro motive force in alternating current circuits, for controlling the lighting of
theatres, and for other useful purposes.
In the further description of this invention, reference is made to the necom-
panying drawings, in which Fig. 1 is a representation, partly in diagram, of one
form of our apparatus for regulating the electro motive force in an alternating
current circuit for theatre lighting, in which the choking coil is divided in sections
which are successively put in or cut out of circuit by actuating the switch shown;
Fig. 2 is the same, hit the sectional arrangement of the choking coil is dispensed
with and resistaures are interposed in the lamp circuit insteal; Fig. 3 represents
a front elevation of the means of regulating the electro motive force of a circuit
with the communicating gear between the regulating board and a choking coil,
and Fig. 4 is a side elevation of the same. Fig. 5 is a front elevation of part of a
regulating board showing an assemblage of circuits with the mears of regulating
them singly or in combination; and Figs. 6 and 7 are enlarged detail views of
parts of the aforesaid apparatus.
In the first part of our invention, shown in Fig. 1, we employ choking coils a,
but instead of the series coil winding being continuous, as usual, each coil is divided
into sections connected to a separate contact terminal b', of a regulating switch c,
preferably of the circular or rotating type, as shown. Upon the axle of the
regulating switch or regulator c, is secured a bridge piece el, one end bearing
continuously upon a central disc plate or concentric segment which forms one
terminal, while the other end during its rotary movement bears upon the successive
contact terminals of the aforesaid sections of the choking coil a, and of the
general terminal 2 of the main circuit which cuts them all out. Consequently,
the regulator is adapted to switch the choking coil a into or out of circuit
gradually, the amount of graduation possible being governed by the number of
sections into which the coil is divided. In addition to the bridge piece c' an
ebonite or other insulating disc or bush & carrying a pulley d' is securel to the
axle, and turns with it as indicated in Figs. 4 and 6. A brass strip d² is attached
at one end to the pulley in such a manner that in turning the axle of the regulator
in one direction, the brass strip is wound upon the pulley d', while in turning it in
the other direction, the brass trip is unwound. At the other end of the strip the
iron core a of the choking coil a is suspended, so that while turning the axle and
the bridge piece cover the aforesaid sectional contacts, the iron core is simul-
taneously raised into or lowered out of the interior of the choking coil. It is

page_text: important to note, however, that at the beginning of the movement which puts the
first section of the choking coil into circuit, the core al is so suspended as to be out
of the coil a short distance, and it only enters the coil after one or more of the
sections have been put in circuit. By this means the potential is gradually
reduced, so that a sudden drop in the voltage or electro motive force, in the
alternating current circuit under control, is entirely avoided; thus differing from
the methods hitherto employed. Conversely in turning the regulator in the
opposite direction to unwind the strip and lower the core, the electro motive force
is gradually increased in the circuit, so that any sudden variation in the light-so
objectionable in theatres-is prevented. The regulator is conveniently placed on
the top of a choking coil, the latter forming a base of support for it, as shown in
Figs. 3, 4 and 6.
.
Several regulators with their respective e ils are employed in the lighting of a
theatre, each controlling a separate circuit. As it is frequently desirable to
regulate two or more circuits simultaneously, while reserving the power to regulate
each circuit separately, an arrangement called a check wheel is used for each
eirenit, and several check wheels, corresponding to the number of circuits to be
regulated, are mounted together upon a regulating board, as shown in Fig. 5.
Each check wheel is secured upon one end of a short axle arranged to work
horizontally in a suitable bearing, the other end having also secured to it a small
mitre wheel as shown in Fig. 7. A spring plonger pin is fitted to pass thro agh
a socket bored in the check wheel near its periphery, and a metal disc is mounted
immediately behind this so as to be free to turn freely upon the axle. On the lace
of the dise next to the check wheel, a series of holes is drilled closely together
around its face to coincide in position and diameter with the end of the spring
plunger pin (as shown in the per part of Fig. 3; that the latter can be
spring into the hole in line with the pin, in order to lock the two together and
cmmunicate motion from une to the other. The periphery of the dise is cut as
a worm wheel, and it is driven by a worm e mounted or cut upon a long horizontal
shalt (Figs. 3 and 4, which also carries other driving worms to actuate a line of
similar check wheels. By means of a handwheel or handle, at the end of this
long shaft, all the dises' connected therewith are turned simultaneously, and
with them all the check wheels which are connected to the dises by meaus
of their respective spring plunger pins e. But if any one of the pins e is
disconnected from its corresponding check wheel e, its circuit is unaffected by
the general regulation of the others when the long horizontal shaft is turned.
Moreover, the said circuit may then be separately controlled by its own check
wheel, which is disconnected from the disc, in the following manner.
The small mitre wheel (Fig. 7) on the axle of the check wheel gears into a
corresponding one secured upon a vertical or other shalt working in the bracket
bearings already referred to, and connected in the same or an equivalent manner
to the axle of the regulating switch c. Consequently, any movement of the
check wheel aforesaid is transmitted by the gearing, and shafts to the
regulator (wherever it may be convenient to place it), which is turned to cut in
or out of action the several sections of the choking coil as already explained,
and to wind up or lower the core, as the case may be; a wheel and suitable
counterbalance, assisting the operation. In the same manner all the check
wheels, which are connected with their respective metal discs, are caused to move
simultaneously by turning the long horizontal shaft at the regulating board; and
thus the circuits controlled by them are regulated simultaneously. If all the light
circuits of the theatre are arranged, for example, in three divisions-either of
colour, or of position in the house-(ns indicated in Fig. 5), and all the circuits in
each division are arranged at the regulating board to be worked on the plat
form from one long horizontal shalt e, then each of the three shafts of the
three divisions may be separately worked by its hand wheel e, as shown, or they
may be connected together by suitable gearing, (not shown) and worked by one
movement simultaneously from the working platform i, Fig. 5. Thus all the

page_text: lights in the use may be raised or lowered gealnally at the same tim³, or each
division separately, except such circuits as may be disconnected at the check
wheel. A chce wheel e, and a regulating switch may, however, be combine 1,
as indicate in Fig. 2.
We
'e sometimes insert sectional resistances between the successive contact
terminals of the regulating witch or regalator, in which case the choking coil a
is wound continuously as indicated in Fig. 2. The resistances are preferably
arranged to increase in degree as shown, and the switch so connected across the
terminals that when the sections o the resistances are all cat out, the choking
coil is shit ritenited; so that practically no current passes through it. As the
sections of the re-ist ince are successively switchel into cir nit, the current is
increasingly diverted through the coil until the resistance reaches its utmost
value, when the circuit through it can be broken and all the current pass at
through the choking coil a; the core a', meanwhile being woun1 into the coil, as
in the former example. The resistance should be suitably proportioned to the
coil, so that any sudden drop in the potential difference across the circuit which
is to be controlled, is avoided.
In combination with either of the foregoing arrangements, when it is desirable
to fix the core we use an adjustable non-magnetic tube or screen over the core
(not shown), to produce the same impe lance effect that is otherwise produced by
moving the core into the coil; the uncovering of the core by the invement of
the screen being equivalent to the insertion of the core in the coil. The tube is
sletted to avoid excessive heating; and the movement of the screen is prolucel
in the same manner as that of moving the core, the action, however, being
reversed.
The term choking coil is in common use, but it is to be understood as meaning
impedance coil.
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 :-
1. The herein described apparatus for regulating the electro motive force in
alternating current circuits substantially as and for the purpose specified and shown
in the drawings.
2. In an apparatus for regulating the potential or electro motive force in a
alternating current circuit, the combination of a choking coil having its winding
divided into sections, a regulating switch arranged and operating to cut the said
sections in or out of circuit, and an adjustable core movable in or out of the said
choking coil concurrently by or with the movement of the said switch, substantially
as and for the purpose herein described and shown by the drawings.
3. In an apparatus for regulating the potential or electro motive force in an
alternating current circuit, the combination of a choking coil with an adjustable
core, a regulating switch with means to operate the said adjustable core, and
graduated re-istances arranged and operating to vary the flow of current through
the coil by the movement of the regulating switch, substantially as and for the
purpose herein described and shown by the drawings.
4. In an apparatus for regulating the potential or electro motive force in an
alternating current circuit, the combination of a choking coil, a regulating switch
and pulley insulated from the said switch, a core suspended from the said pulley
and movable in or out of the said choking coil by the movement of the switch, and
a check wheel and communicating gear for working the atoresaid switch, sub-
tantially as and for the purpose herein described and shown by the drawings.
5. In an apparatus for regulating the potential or electro motive force in an
alternating current circuit, a check wheel e, provided with a spring plunger pin e,
and combined with a metal disc formed as a worm wheel and having a series of
hules upon its face coinciding in position and diameter with the end of the sai
spring plunger pin, combined with a shaft e, and worm e engaging with and

page_text: adapted to drive the said metal disc, substantially as and for the purpose herei i
described and shown by the drawings.
Dated this 2nd day of July 1896.
FAIRFAX & WETTER,
433 Strand, London, Agents for the Applicants.