Improved System of Switching and Regulating Apparatus for Central Stations for the Generation and Distribution of Electrical Energy.
Year: 1894

page_text: Date of Application, 27th June, 1894
Complete Specification Left, 27th Apr., 1895-Accepted, 8th June, 1895
PROVISIONAL SPECIFICATION.
Improved System of Switching and Regulating Apparatus for
Central Stations for the Generation and Distribution of
Electrical Energy.
I, JOHN SMITH RAWORTH, of 49 Queen Victoria Street, in the City of
London, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention has reference to certain improvements in switching and regulating
apparatus and in their connection and combination to form a complete and improved
system.
Some of the details used in carrying out my invention constitute the subject
matter of former Letters Patent granted to me vis. Nos. 19,404 and 23,675 of 1892 ;
and 11,384 and 18,170 of 1893 the safety fuse hereinafter mentioned forming the
subject matter of Letters Patent No. 2703 of 1893 granted to D. Bates. The main
feature of my improved system is simplicity which is primarily obtained by the
parallel working of exciters and dynamos.
The following description applies in the first place to an alternate current system
and secondly to a continuous current system.
All the exciters feed a pair of omnibus conductors. No switchboards are used,
but opposite each exciter stands a cast-iron switch-pillar which automatically closes
the circuit when the E.M.F. of the exciter rises slightly above that of the omnibus
conductors. It also opens the circuit and cuts off the exciter whenever, either by
design or accident, the E.M.F. of the exciter falls below that of the conductors.
Thus the operations are performed at the right moment of minimum current and
are unaffected by the clumsiness or nervousness of the attendant.
A full description of switching apparatus of this kind is described in my former
Specification No. 23,675 of 1892.
I now come to the alternators. Again there is no switchboard, but opposite each
alternator stands a cast-iron switch-pillar, by means of which all the operations
necessary for putting that machine in or out of circuit are performed.
The pillars are fitted with three iron handles, which perform the following
functions:-
:-
The left handle closes the exciting circuit on to the field magnet.
The right handle puts on the synchronisér.
These two operations being performed, the middle handle, which operates the
main switch, is liberated and may be used to close the circuit.
The closing of the main switch locks the field switch and turning off the
synchroniser locks the main switch.
There is an independent trigger on the main switch, which is released by the
current attaining the normal voltage. A full description of this switching gear is
given in my former Specification No. 23,675 of 1892.
The object of all this interlocking is to prevent the attendant closing or opening
the switches in their wrong order, which in the past has been a fruitful source of
lisaster.
There is still one chance of accident left; the attendant may close the dynamo
ircuit when unsynchronised, but this is effectually prevented by a trigger which is
released only at the instant of complete synchronism. This device so far as I am
aware is novel and is not included in my previous Specifications.

page_text: Each alternator switch-pillar is provided with a rheostat for correcting the
temperature resistance of the field circuit, but it is not used for regulating
the E.M.F., nor for varying the load on the machine.
The leads from the switch-pillars are not coupled direct to omnibus bars or
conductors, but are taken direct to the distributing switch room, where they are
plugged into omnibus tables.
The advantages of this arrangement are:-
First The use of conductors of enormous section is avoided.
-
Second Any switch-pillar or any section of the station can be entirely isolated
by withdrawing the plugs from the omnibus tables.
The arrangement of the omnibus tables is a most important feature. There are
two complete sets, each representing one half of the total power of the station and
each set can be worked either with or without the other, so that repairs to either
set can be executed with perfect safety.
From the omnibus tables conductors are taken to the circuit or feeder switch-
pillars, which are constructed to perform several functions:-
:-
(a) To connect the circuit or to break it under full load in case of emergency.
(b) To regulate the E.M.F. of the circuit.
(c) To change the fuses.
(d) To cut itself out of circuit without interrupting the current.
The central handle operates the main switches; the cross shaft provided with
two hand wheels regulates the degree of augmentation of E.M.F. in the circuit;
the right handle changes the fuses; and the left handle cuts the pillar and all its
instruments out of circuit. The handles are interlocked to prevent improper use of
them.
In the event of a failure of the fuses, a new set can be inserted by a single turn
of the handle after opening the main switch.
I now come to the important questions of regulation.
First-The division of load between the several alternators.
Second The control of the E.M.F. of the whole station as measured at the
omnibus tables.
The first is effected by regulating the governor of each engine by hand whilst
running until each dynamo takes its equal share of load with the others. There is
no other way of producing this result. Any alteration of the field of one alternator
simply varies the lead or lag of that alternator as compared with the others, but its
speed remains unaffected and consequently its steam supply and energy remain
constant. There can therefore be no variation in relative load, except by relative
alteration in the steam supply as regulated by the governor.
The control of the E.M.F. of the whole station, as measured at the omnibus
tables, is effected by means of an electric circuit influencing the throttle valve
governors of the exciters. Each exciting engine has a solenoid arranged to act
upon the adjusting lever of the governor; the speed of the engine can therefore be
varied by varying the current in the solenoid. All the solenoids are in parallel on
a circuit, in which is placed a rheostat regulated by hand or automatic mechanism.
It is part of the system that the controlling solenoids shall be always in circuit, so
that no exciter can be started without being at the same time under control of the
switch-room.
The action of the regulating circuit is to increase the speed of the exciter, so that
in the event of the regulating circuit breaking down, the only effect would be that
the E.M.F. would fall and would have to be raised by hand adjustment of the
governors. A full description of the regulating apparatus is given in my former
Specification No. 11,384 1893.
From the above general description it will be seen that the system employed
reduces the possibility of accidental mistakes in switching to a minimum.
The dynamo attendant has nothing to do beyond putting his machines on or off
the circuit according to orders received from the switch-room. The switch-room
attendant regulates the E.M.F. of the several circuits as required, and the regulator

page_text: (automatic or otherwise) keeps the voltage steady according to requirement or
instructions. Any part of the system can be isolated for repairs; and extension
only necessitates repetition without reconstruction.
The next point to be considered is the arrangement of safety fuses.
The exciters have no fuses, but the automatic switch itself acts as a zero-cutout
to prevent the return of current on an exciter.
The alternators are provided with return current fuses, which cut the machine
out of circuit with a return current of about half the normal output.
A description of these fuses is given in my former Specification No. 19404, 1892.
The only other fuses in the system are on the inner conductors of the concentric
cables issuing from the circuit switch pillars.
The particular form of fuse I prefer to use is the invention of Mr. D. Bates, and
is as effective as it is simple and ingenious. The fuse wire enclosed in a strong
stoneware tube, open at both ends. When the fuse breaks, the explosive force of
the heated air blows the arc out at both ends of the tube. A full description of
this fuse is given in Specification No. 2703 of 1893.
Even with 2,000 volts and 250 amperes, with a length of only 8 inches, the
interruption of the circuit is certain and immediate on the melting of the fuse.
The fuses and all the switches are provided with my Patent contacts which
maintain their contact faces parallel under pressure. They have all the advantages
of laminated contacts and at the same time are stronger, cheaper and more
mechanical. A full description of these contacts is given in my prior Specification
No. 18,170 of 1893.
The main high-tension switches on the alternator and circuit pillars are immersed
in water. Although there is no necessity under normal conditions to break the
circuits under load, yet in case of emergency a thousand horse power can be
suddenly cut off with no worse result than a small momentary spark.
The above description of the switching arrangements for an alternate current
generating station apply equally to a low tension station with the following
exceptions. When shunt wound self exciting dynamos are used, the automatic
switch pillars are employed to connect the dynamos with the omnibus bars or
tables.
The circuit switch pillars regulate the E.M.F. in the circuit or feeder not by
augmentation but by reduction, the means used being resistance or counter E.M.F.
cells and the mechanism consisting principally of single tooth and star wheels which
produce a definite movement corresponding to a definite difference of resistance a
counter E.M.F. for each revolution of the handle and further assure the absolute
centralization of the contact pieces.
Dated this 27th day of June 1894.
Improved System of Switching and Regulating Apparatus for
Central Stations for the Generation and Distribution of
Electrical Energy.
I, JOHN SMITH RAWORTH, of 49 Queen Victoria Street, in the City of London,
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 :-
This invention has reference to certain improvements in switching and regulating

page_text: apparatus and in theft connection and combination to form a complete and improved
system.
Some of the details used in carrying out my invention constitute the subject
matter of former Letters granted to me vis. Nos. 19,404 and 23,675 of 1892; and
11,384 and 18,170 of 1893, the safety fuse hereinafter mentioned, forming the
subject matter of Letters Patent No. 2703 of 1893 granted to D. Bates.
The main feature of my improved system is simplicity which is obtained as I will
now proceed to explain by aid of the accompanying drawings the exciters and
dynamos working in parallel as well understood.
Fig. 1 (Sheet) is a diagram showing the general arrangement of my improved
system as applied to an alternate current system.
A, A2, A3, A4, A, and A represent six alternators which are excited in
parallel by four continuous current exciters with their steam engines, marked
respectively E', E2. E³, and E', which deliver their current into two main
conductors C and C2, which are respectively positive and negative.
No switchboards are used, but opposite each exciter stands a cast-iron switch-
pillar C which automatically connects the said exciter with the main exciting
conductors CC when the E.M.F. of the exciter rises slightly above that of the
said conductors. It also opens the circuit and cuts off the exciter whenever, either
by design or accident, the E.M.F. of the exciter falls below that of the
conductors. Thus the operations are performed at the right moment of minimum
current and are unaffected by the clumsiness or nervousness of the attendant. The
automatic exciter switch-pillars C* are shewn clearly in each case inserted in
the branch conductors E* on the left-hand side of the two exciters E' and E2, and
ou the right-hand side of the two exciters E³ and Et.
A description of switching apparatus of this kind, which, separately considered,
forms part of the subject matter of former Letters Patent granted to me No. 23675
of 1892, is hereinafter given.
The alternators A', A2, A3, A', A³, A have no switchboard, but opposite them
stand the cast-iron switch-pillars S¹, S2, S3, S4, S5 and Se respectively, by means of
which all the operations necessary for putting any one of the alternators in or out
of circuit are performed. These pillars are each fitted with three iron handles
which perform the following functions:-
The left handle closes the exciting circuit on to the field magnet.
The right handle puts on the synchroniser.
These two operations being performed, the middle handle, which operates the
main switch, is liberated and may be used to close the circuit.
The closing of the main switch, locks the field switch, and turning off the
synchroniser locks the main switch.
There is an independent trigger on the main switch, which is released by the
current on its attaining the normal voltage. A full description of this switching
gear, which, separately considered, forms part of the subject matter of the above
mentioned Letters Patent No. 23,675 of 1892, is hereinafter given.
The object of all this interlocking is to prevent the attendant closing or opening
the switches in their wrong order, which in the past has been a fruitful source of
disaster.
There is still one chance of accident left; the attendant may close the dynamo
circuit when unsynchronised, but this is effectually prevented by a novel
construction and arrangement of trigger device which is released only at the
instant of complete synchronism. This trigger device is also hereinafter more
particularly described.
Each alternator or main switch-pillar S¹ S². . . Se is provided with a rheostat
for correcting the temperature resistance of the field circuit, but it is not used for
regulating the E.M.F., nor for varying the load on the machine. The primary
alternating current leaving the alternators A1, A2, A3, A', A³, A passes through
the main switch-pillars, S1, S2, S3, S+, S³, and S, to concentric cables S*, which
instead of being coupled direct to omnibus bars or conductors as usual, are taken

page_text: direct to the distributing switch room where they are plugged into the main
omnibus tables O¹ and 0%, which are connected by main conductors and switches to
the distributing omnibus tables, O2 and 03, which, by means of the large switch S7,
may be connected or disconnected as required.
The advantages of this arrangement are:-First: --The use of conductors of
enormous section is avoided. Second :-Any switch-pillar S¹. . . . . S%, or any
section of the station, can be entirely isolated by withdrawing the proper plugs
from the omnibus tables O' or 0.
The arrangement of the omnibus tables is a most important feature. As will be
scen, there are two complete sets, viz. 01 02 and 03 04, each representing one
half of the total power of the station, and each set can be worked either with or
without the other, so that repairs to either set can be executed with perfect
safety.
From the omnibus tables 02, 0³ concentric conductors O* are taken to the
circuit or feeder switch-pillars D¹, D², D³, D', D³, Dº, D², D³, D³, D1, each of
which is constructed to perform several functions, namely,
(a) To connect the circuit, or to break it under full load in case of
emergency.
(b) To regulate the E.M.F. of the circuit.
(c) To change the fuses.
(d) To cut itself out of circuit without interrupting the current.
Each feeder switch-pillar is provided with a central handle that operates the
main switches, and with a cross shaft provided with two hand wheels for regulating
the degree of augmentation of E.M.F. in the circuit; the right handle changes
the fuses, and the left handle cuts the pillar and all its instruments out of
circuit. The handles are interlocked to prevent improper use of them.
In the
event of a failure of the fuses, a new set can be inserted by a single turn of the
handle after opening the main switch. Such a feeder switch-pillar is hereinafter
fully described.
From the switch-pillars, D', D2, D3, D4, D³, Dº, D², D³, Dº, D are led the
concentric cables D* which serve as feeders to the various transforming and
distributing centres F, which are shown as circles on the diagram, and from which
the low-tension distribution systems G emanate. It will be seen that whereas
the switch-pillars D4, D5, D6, and D' are each provided with two feeders D*, the
switch pillars D1, D2, D³, D, D³, and D10 are each provided with three feeders,
the number and sizes of the feeders being selected to suit the requirements of the
distributing centres.
I now come to the important questions of regulation.
First-
A³, Aº.
-The division of load between the several alternators A¹, A², A³, A',
Second-The control of the E.M.F. of the whole station as measured at the
omnibus tables 01, 02, 03, 01.
The first is effected by regulating the governor of each alternator engine by
hand, whilst running, until each dynamo takes its equal share of load with the
others. There is no other practical way of producing this result. Any alteration
of the field of one alternator simply varies the lead or lag of that alternator as
compared with the others, but the speed of its driving engine remains unaffected
and consequently the steam supply and energy of such engine remain constant.
There can therefore be no variation in relative load, except by relative alteration
in the steam supply as regulated by the governor.
The control of the E.M.F. of the whole station, as measured at the omnibus
tables, is effected by means of an electric circuit, influencing the throttle valve
governors of the engines driving the exciters E¹ .. E. Each exciting engine
All
has a solenoid arranged to act upon the adjusting lever of the governor; the speed
of the engine can therefore be varied by varying the current in the solenoid.
the solenoids are in parallel on a circuit in which is placed a rheostat regulated by
hand or automatic mechanism. It is part of the system that the controlling

page_text: solenoids shall be always in circuit, so that no exciter can be started without being
at the same time under control of the switch-room. The action of the regulating
circuit is to increase the speed of the exciter, so that in the event of the regulating
circuit breaking down, the only effect would be that the E.M.F. would fall and
would have to le raised by hand adjustment of the governors. A full description
of this regulating apparatus which, separately considered, forms the subject
matter of former Letters Patent granted to me No. 11384 of 1893, is hereinafter
given.
From the above general description it will be seen that the system employed
reduced the possibility of accidental mistakes in switching to a minimum. The
dynamo attendant has nothing to do beyond putting his machines on or off the
circuit according to orders received from the switch-room. The switch-room
attendant regulates the E.M.F. of the several circuits as required, and the
regulator (automatic or otherwise) keeps the voltage steady according to
requirement or instructions.
Any part of the system can be isolated for repairs; and extension only
necessitates repetition without reconstruction.
I will now describe in detail, the construction of the switch-pillars, omnibus
tables, and electro-motive force regulator herein before referred to.
Figs. 2 and 3 of the accompanying drawings, (Sheet 2) are elevations at right
angles to each other, showing, diagrammatically, the construction of one of the
automatic exciter switch-pillars shown at C* in Fig. 1.
It comprises two solenoids or electro-magnets A B between which is placed an
iron armature C carried by a rod D, which constitutes the movable rod of the
switch, and to which the movable contact E is secured. At each end of the
movement of this rod, the said armaturę C comes actually or bearly, into contact
with one or other of the above mentioned solenoids. The solenoid A with which
the armature C is in contact when the switch is open, is wound differentially, one
set of coils being in a derived circuit or shunt on the main exciting conductors, C¹ C²,
and the other set being in a shunt on the leads E* of the exciter and wound in the
opposite direction to the first set. Consequently it is not until the action of the
solenoid on the armature C is neutralised by reason of the difference of potential
at the terminals of the dynamos being equal to or slightly greater than the
difference of potential existing in the main exciting conductors, that the said
armature C is released to allow of the closing of the switch. When this occurs
the switch can be closed by hand, or by a weight or spring attached to the lever.
I prefer to employ for this purpose the arrangement illustrated, in which F is a
weighted lever loosely mounted on a rock shaft G to which, at one end, is fixed a
disc H having a notch 1 in which the tooth of a pawl J carried by the lever F
engages. At the other end of the shaft G is a crank whose pin K bears against
the underside of a projection L on the rod D so that when the crank pin is moved
upward, it carries the said rod with it, whilst when the rod is moved downward, it
depresses the pin and turns the crank in the opposite direction. A fixed stop M is
arranged in proximity to pawl J in such a position that it engages with the tail J'
of the said stop when the lever F turns, and consequently disengages the said pawl
from the notch I in the disc H. It will thus be seen that so long as the armature C
is kept down by the attraction of the solenoid A, the weighted lever and connected
parts will be maintained in the position shown in Fig. 2, in which position they are
placed or adjusted originally by hand. When however the armature C is freed
from the attraction of the solenoid A, the weighted lever F partly rotates the
disc H and consequently the crank K, thereby raising the rod D and forcing the
contact piece or pieces E between the terminal or terminals E', there being two
such terminals in the example shown, marked respectively + and By the time
the contact piece E is in position, the tail J₁ of the pawl J comes against the
stop M and the pawl is disengaged, so allowing the lever F to fall by gravity.
At this time also the armature C is brought into close proximity to the solenoid B.
This solenoid is series wound, and the current from the exciter, or a portion
1.

page_text: thereof, passes through it, thereby serving to keep the armature C and, connected
parts raised after the lever F has been released. Should however the current from
the exciter cease from any cause, the solenoid B will release its hold on the said
armature and allow the switch to open by gravity.
Fig. 3A (Sheet 2) is a diagram showing the electrical connections of the exciter
switch-pillar shown in Figs. 2 and 3. F2 is the exciter commutator; A the
differentially wound shunt solenoid in connection with the main exciting con-
ductors C1, C2 and the leads E* of the exciter F¹; B the series solenoid; C the
armature with movable rod D and contact E; and E¹ the main switch terminals.
Fig. 4 (Sheet 2) is a general diagrammatic view partly in section, and Figs. 5
and 6 are detail views, showing the construction of one of the alternator or main
switch-pillars shown at S¹
S6 in Fig. 1.
N, O, and P are three switch handles which are interlocked, and of which N
controls the circuit for the synchronising device, () controls the main switch,
and P the exciting circuit for the field magnets of the alternator. These handles
are interlocked respectively by means of the three contiguous stop discs N₁ O₁ Pl
mounted on their respective spindles or axles. The two outer discs N' and P¹ are
formed with recesses N2 and P2 respectively, while the inner wheel O is formed
with two corresponding recesses 02, 0³, arranged diametrically opposite each other.
The relative arrangement of the discs is more clearly shown in plan in Fig. 6.
The discs O and Pi have corresponding lateral projections 0 and P2 respectively
which interlock when brought into proximity, as will be readily understood. To
guard against closing of the main circuit before the proper potential has been
reached, an electro-magnetic locking device is provided which locks the disc O',
until such time as the generator is giving the working potential. This locking
device comprises a catch Q adapted to take into a notch 04 in the disc O¹ and
carried by the armature Q₁ of a solenoid or electro-magnet Q2. The catch is kept
in engagement with the disc O' by a spring or springs Q³ capable of adjustment,
and whose force is so regulated that when the potential reaches the proper degree,
the armature is attracted and the catch Q is withdrawn, thereby permitting the
disc O and the handle O connected therewith, to be operated when unlocked by
the disc N' and P¹.
The main switch proper comprises a pair of plugs R adapted to enter spring
fingers or sockets S, and carried by rods R¹ which work in cylinders T¹ secured
each upon the upper part of a case or cell T of insulating material. The rods R
are secured to pistons R* formed of metal gauze stampings or otherwise suitably
arranged to make efficient electrical contact with the inner walls of the cylinders T¹.
The said plugs are operated from the handle O, through the medium of rods R²,
which pass through the upper ends of the cylinders T₁, and are secured to a cross
bar U of insulating material, which is carried by a rod V mounted between suitable
rollers or guides V₁ and connected at its lower end, by means of a connecting
rod V2, with a crank pin O on the disc O¹. By this means when the handle O is
turned in one direction, the plugs R are brought into proper contact with the spring
fingers or sockets S, and the main circuit thereby completed through the said fingers
or sockets and plugs, the rods R' and the walls of the cylinders T', and the main
leads terminating at the said cylinders and fingers. By a movement of the handle O
in the opposite direction the circuit is of course opened.
Undue sparking in opening the circuit is prevented by partly filling each cell T
with water W and oil W₁, the spark or arc produced on breaking contact, if
sufficiently powerful to pass through the water, being extinguished by the oil
above it.
A special switch may be provided for closing the exciting circuit of the corre-
sponding alternator. This switch comprises a bell crank switch lever X, spring
contact fingers X' between which the free end of the switch lever X can pass,
and auxiliary carbon contacts X2, X2 for preventing sparking between X and X'.
The movable carbon contact is carried by a lever X3 pivoted co-axially with the
lever X and provided with a spring X which tends to pull the carbon contacts

page_text: together. The lower arm of the switch lever X is connected by a rod P³ with a
crank pin on the disc P¹ whereby it is operated. In its turn this switch lever X
actuates the lever X3 of the auxiliary contact, by means of a projection or heel X³
which bears against the lower arm of the said lever X3 as shown. The size of the
projection or heel, and the range of movement of the parts, are so arranged that
there is a certain amount of lost motion between X and X3 so that the auxiliary
contacts X2, X2 will be closed by the action of the spring X before X and X
come into contact, and will remain in contact, or at least in arcing distance,
until X and X' have passed out of contact. In the case of the handle N, a
spring N³ is connected to a pin on the disc N¹ in order to give a quick closure of
the switch connected therewith.
Fig. 7 (Sheet 2) shows, diagrammatically, the trigger device used for preventing
the main switch being closed when the dynamo is unsynchronised. O* is a disc on
the centre shaft of the switch pillar (Fig. 4) which controls the main switch;
S, S, are two solenoids that are fed from the secondary circuit to the synchronisers
and may be either in series or parallel with the synchronising lamps; T is a pivoted
trigger or catch adapted to engage the disc O* and connected with the armature S¹
of the solenoids; and U is a small spiral spring connected with the trigger and so
adjusted as to overbalance the pull of the solenoids at all times, except when the
full voltage is attained and when the incoming dynamo is exactly synchronised
with the circuit, at which instant the pull of the solenoids overcomes the pull of
the spring and the trigger or catch is disengaged from the disc O*. This trigger
device is shown combined with the switch-pillar in Fig. 5.
Figs. 8 and 84 (Sheet 3) show diagrammatically the arrangement of all the
connections in connection with the alternator switch-pillar (Figs. 4 to 7 inclusive)
hereinabove described.
In Fig. 8 E represents the armature of the exciter; F the field coil of the
alternator; F2 the field switch; F³ the field am-meter; and F4 the field rheostat.
In Fig. 8, R and R³ represent the return current fuses on a main alternating
circuit. S1 and S2 are the main water switches. S³ is the synchroniser switch.
S and S are the synchroniser lamps. O* is the safety disc controlled by the
solenoids S and trigger or catch T, as described above, to prevent the switches
being operated when the dynamo is unsynchronised. S is the synchroniser, the
connections of which are shewn, but not described, as they are well understood.
S7 is the synchronising volt-meter in parallel with the synchronising lamps and
used for the same purpose. V₁ is the main volt-meter which is fed from a secondary
circuit of a small transformer V³, of which the primary is connected directly across
the high tension mains as shown.
Fig. 9 (Sheet 4) is a side elevation, to a larger scale, of the omnibus tables,
and connections shown in Fig. 1. The reference letters in Fig. 9 correspond with
those in Fig. 1, O' and O being the collecting tables from the alternators, and
02 and 0³ the distributing tables to the circuit pillars. The current enters and
departs by means of concentric conductors which are shown joined up to the tables
by means of hand connectors N¹, N³, and N¹ being connected to the inner con-
ductor, and N2 to the other conductor. The tables to which the said connections N¹
and N2 are made, have the extreme difference of potential between them, and are
insulated from each other with extreme care. It will be observed that the current
in passing from the table O¹ to the table O2 passes through the switch S¹³ the
am-meter M and the switch S, and there is a similar arrangement in connection
with the tables 03 and 0%, the switches being marked S1 and S1 and the
am-meter M². The switch S12 is on the return or outer conductor, and when
used in connection with the switch S7, may be employed to completely isolate
one half of the system.
Fig. 10 (Sheet 5) is a diagram of the electrical and mechanical arrangements of
one of the circuit or feeder switch-pillar DI.
Do, arranged in this instance
for three concentric feeders. The transformer or distributing centre is indicated
on the diagram by a large circle marked X. The augmentator or instrument for

page_text: raising the electromotive force of the circuit as desired, is marked P1, and the
impedence coil with screw gear for the adjustment of the influence of the
augmentator Pl, is marked P³, P³ being a cross shaft with. hand wheels P for
operating the screw gear. S20 and S21 are the main switches, the handles and
interlocking gear of which are practically similar to those herein before described
in connection with the alternating synchronising switch-pillar (Figs. 4 to 7
inclusive) and are here marked collectively H³. M³ is the electricity meter;
M a registering am-meter; M³ an am-meter; and M a compound transformer
for a volt-meter M. The fuses S are shewn arranged in two sets of three each
at the top of the diagram, and are controlled by a switch operated by the handle
and disc H', so that the current may be shunted through either set of fuses at will.
The switches for connecting up or isolating the whole pillar and its instruments,
as described, are shewn at S2. They are operated by the arms S2, which are
fixed on the same spindle, and are operated by the handle and disc H. The
connections to the outer strands of the concentric cable O* from an omnibus table,
are shown by a thick black line, and those to the inner strands by a thick
dotted line.
Figs. 11 and 12 (Sheet 6) are elevations at right angles to each other, and
Fig. 13 a plan of the electro-motive force regulator. Fig. 14 is a general diagram
of the connections showing the application of the system to three exciting engines.
R is an ordinary throttle valve governor, R2 represents a pair of solenoids which
by means of the movable cores R³, rod R', link R' and lever R°, clearly shown in
the drawings, are able to influence the governor R₁ so as to cause the engine to
which the governor is fitted to run at different speeds, and so regulate the E.M!F.
of the electric generator driven by the said engine.
In the diagram Fig. 14, each exciting engine E', E, E³, is fitted with the
regulating arrangement shown in the Figs. 11, 12 and 13, and the several solenoids
are all coupled in parallel on a circuit R, fed with current from a source of electro
motive force R°. The strength of this current is controlled by a rheostat Rº,
which may be regulated by hand or by some automatic mechanism.
The next point to be considered is the arrangement of safety fuses.
The exciters F1, F2, F³, F, (Fig. 1) have no fuses, but the automatic switch C*
(Figs. 1, 2, 2 and 3), itself acts as a zero-cutout to prevent the return of current
on an exciter.
Each alternator A¹, A is provided in its switch-pillar S'. . . So with return
current fuses R, R' (Fig. 84) such as shown in the Specification of Letters Patent
granted to me No. 19404 of 1892, and which cut the machine out of circuit with a
return current of about half the normal output.
In each return fuse, the current enters, in the example shewn, at the point a¹
of a switch a² from the alternator, and leaves at a3 and has the choice of two
paths, namely:-one through a fuse or cut out at b', and the other through the
switch a² and a conductor a* a portion of which forms the thick winding of a
transformer as the thin winding of which is a shunt to the pair of mains between
which the alternator is placed. The transformer is so arranged that it imparts a
slight additional E.M.F. to the current sufficient to induce it to select the path
through a, a in preference to the path through the fuse or cut out b. With this
arrangement should the alternator fail to give. its normal E. M.F., current would
pass from the mains to the alternator and would pass through the fuse or cut
out 6, as the E.M.F. of the transformer a would oppose its passage by the
path a, a. Under these circumstances, the said fuse or cut out would act and
liberate a weighted lever as which it previously held up, and permit the same to
fall and strike open the switch a², thus preventing the alternator from being injured
by the returu current.
Figs. 15 and 16 (Sheet 6) represent in sectional side elevation, and end view,
respectively, a "Bates" high tension fuse. K' is a porcelain tube provided with
metallic contact pieces K2, which engage into fixed contact sockets, one of which
is shown at K³. There is a hole right through the porcelain tube, in which is
B

page_text: placed the fuse wire K' which is in metallic contact with the contact pieces K².
It will be observed that the hole through the porcelain tube K2 is open at both
ends.
The contact pieces K³ used in this switch and in all the other parts of the
apparatus hereinbefore described are preferably constructed in one or other of the
ways shewn on Sheet 7. On this sheet Fig. 17 represents the arrangement of
contact for ordinary plain parallel contacts; Fig. 18 represents a wedge-shaped
contact which is used when it is desirable to make or break the contact with a
minimum amount of force, as in automatic switches; Fig. 19 represents the
cylindrical pattern which is used principally for water switches, as shown at S"
and S in Fig. 10 (Sheet 5): Fig. 20 represents the application of the contact to
the interior of a tube; and Fig. 21 its application to the exterior of a rod or
tube, as applied in the construction of the large switches shown at S7, S1, S1,
S15, and Si, in Fig. 5.
The main high tension switches on the alternator and circuit switch-pillars are
immersed in water as hereinbefore described.
Although there is no necessity under normal conditions to break the circuits
under load, yet in case of emergency a thousand horse power can be suddenly cut
off with no worse result than a small momentary spark.
The above description of the switching arrangements for an alternate current
generating station apply equally to a low tension continuous current station with
the following exceptions. When shunt wound self exciting dynamos are used, the
automatic switch pillars C* (Fig. 1) are employed to connect the dynamos with
the omnibus bars or tables O', 0, and the circuit or feeder switch pillars D' D³°
(Fig. 1) regulate the E.M.F. in the circuits or feeders not by augmentation but
by reduction, the means used being resistance or counter E.M.F. cells, and the
mechanism consisting principally of single tooth and star wheels which produce a
definite movement corresponding to a definite difference of resistance or
counter E.M.F. for each revolution of the handle and further assure the absolute
centralization of the contact pieces.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. My improved system of switching and regulating apparatus for central
stations for the generation and distribution of electrical energy substantially as
herein before described and illustrated by Fig. 1 of the accompanying drawings.
2. The modification adapted for the generation and distribution of low tension
continuous currents substantially. as described.
3. The combination with switching apparatus of the kind herein before described
and illustrated in Figs. 4, 5, and 6 of the accompanying drawings of the trigger
device shown in and described with reference to Fig. 7 for the purpose of preventing
the dynamo circuit being closed when unsynchronised as set forth.
4. In apparatus for the distribution of electricity, the use of main omnibus and
distributing tables constructed arranged, applied and operating substantially as
herein before described and illustrated in Figs. 1 and 9 of the drawings annexed.
Dated this 27th day of April 1895.
JOHN SMITH RAWORTH.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.