Improvements in the Distribution of Electrical Energy.
Year: 1893

page_text: Date of Application, 8th Apr., 1893
Complete Specification Left, 5th Jan., 1894-Accepted, 10th Mar., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Distribution of Electrical Energy.
I JAMES WHITCHER of 14 Orde Hall Street, Bloomsbury, London, W.C.
Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
:-
In a system of electrical distribution with alternating or continuous currents,
consisting of high-pressure supply mains feeding through transformers into a
network of low-pressure distributing mains, use the following means to secure
control over the transformers in circuit, in order that some of these transformers
may be magnetically put out of action during periods of light load: The object of
this it is well known is to avoid the loss of energy which goes on constantly in a
transformer when it is magnetically active.
I.distribute the high pressure current from the central station or other points by
means of conductors arranged on the well-known "three-wire" principle, the line
of mains consisting of three conductors between one pair of which a potential
difference is maintained double what exists between any other pair.
The distributing or low-pressure network is also carried out on the same principle.
I arrange the transformers by which the electrical energy is transferred to the
low-pressure network thus:-I place the major proportion of the transformer
capacity in connection across the "extreme or outside conductors of both primary
and secondary three-wire mains, the remainder of the transformers I connect part
between the "middle or neutral conductor and one of the "extreme conductors,
and part. between the neutral conductor and the other extreme :-in respect to
both primary and secondary connections.
"
At the central station or at other points, I use special switches controlling the
high pressure circuits, by which one of the extreme conductors of these mains can
be switched over on to the same pole as the other extreme conductor is on, thus
annulling the potential difference between the two extreme conductors but still
retaining that between the neutral conductor and either of these extreme
conductors.
By reason of the said arrangement of transformers the same condition of the
potential differences is brought about by this change in the distributing mains also.
Therefore by this means the larger proportion of transformers can be completely
put out of action when the output from the mains falls below a certain minimum.
For as the E.M.F's on the primary and secondary coils of the transformers are
both reduced-to-zero-no-current-flows-through_them_and_they are therefore
The remainder of the transformers still remain active as before, the direction
only of the relative instantaneous current being changed in those on one side of
the three wire system; and they continue to supply the light load in demand.
magnetically inactive so that no loss goes on in them.
At times of greater load these smaller transformers also act as regulators
maintaining equality of E.M.F. on the two sides of the three-wire distributing
system.
Dated this 8th day of Anril 1893.

page_text: COMPLETE SPECIFICATION.
. Improvements in the Distribution of Electrical Energy.
I, JAMES WHITCHER of 14 Orde Hall Street, Bloomsbury, London, W.C.
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 :-
My invention consists of an improved arrangement of electrical conductors and
transformers, for either continuous or alternating currents whereby it is possible to
put the said transformers in or out of action without mechanical separation or
cutting off of the same from connection with the conductors. Its intention is
therefore to afford convenient and improved means by which much of the loss
occasioned by the constant demand for electrical energy for magnetising the iron
of the transformers whether they are delivering a useful output or not can be
prevented by rendering the said transformers, or some of them, magnetically
inactive during such periods as they are not usefully employed. Such an object, it
is well known, has important bearings on the industrial application of electricity
more especially upon the supply of the same for lighting or power purposes by
means of alternating currents. Hereinafter I describe methods of applying the
invention to such purposes and these developements and applications are comprised
in the invention as part and elaboration thereof.
Hitherto where electrical transformers or converters are used in connection with
electric mains or conductors in or between which an electric pressure or difference
of potential has to be continually maintained, it has only been customary or
proposed to put the said transformers out of action or vice versa, by switching
the coils of the same out of, or into, electrical connection with the mains.
It is obvious that this method requires a set of switches for every transformer or
group of transformers: which switches are actuated by hand or automatically
either by means of change in the flow of current or by means of an electric
current delivered from the supply centre through a separate pilot wire or by means
of devices of a similar nature. But it is well-known that there are grave
objections against breaking a circuit under high electrical pressure; and that
such switches and automatic appliances are in several ways pronounced elements
of weakness in a system of electrical distribution under the conditions that usually
obtain.
It is a distinctive feature of my invention that there is no switching or breaking
of circuits or electrical connections between the transformers & the mains. All
such connections are permanent and direct through the usual double pole safety fuse.
The operation of putting transformers in or out of action is instead performed by
a simple switching or changing over of circuits at the distributing or supply centre.
The arrangement of mains and transformers is such that by this changing of
connections at the distributing centre the electrical potential difference between the
erminals of both the primary and secondary coils of the transformer in connection
with the particular set of mains, may be rendered nil from the condition of being
at the full working potential difference; or rice versa, as it is desired to throw the
transformers out of action or in again as the case may be. It must be noted that it
is an essential condition that this change as to potential difference shall take place
on both primary and secondary sets of mains since it is useless to make one coil
or circuit of the transformer inactive while the other remains active.
In my
invention the change in the potential difference across the secondary mains is
effected by and in virtue of, the change in the primary mains alone.
I carry out my invention in the following manners :-
In systems of electrical distribution of energy for light or power purposes, in
which electrical energy is distributed through a system of mains to a number of
feeding points or substations where it is transferred by means of transforming

page_text: devices into another system or network of mains by which it is further subdivided
and distributed to the various points of demand, I use a line or system of mains
from the supply distributing or generating station, consisting of three conductors
insulated each from the other and extending to the place or district to be supplied.
Most generally these mains would be designed for electrical energy at a high
pressure or electromotive force but I do not restrict my invention to this case alone
as it may have other applications. These mains convey the electrical energy from
the supply centre to the transforming devices at the substations or feeding points.
The three conductors comprising a complete set of mains, or line, will be herein-
"and a
after defined as two
"id
outer and a
wires; or as two "extreme
neutral conductor or wires. Also, as a general and distinctive term the aforesaid
three conductor mains are herein described as primary" mains, which term
comprises all inains carrying current from the supply centre to the points of
transformation, this being the common acceptation of the term.
**
"
k
A set, or line, or circuit of these primary mains may be supplied with electrical
energy in the following manners :-
"
Firstly. Two of the conductors herein designated the "extremes" or "extreme
conductors shall have a certain extreme difference of electrical potential created
between them; and in the remaining conductor herein distinguished as the neutral
conductor shall be established a condition of neutrality in respect to the electrical
condition of the two extremes; that is, a condition of equality of potential
differences between it and the two extreme conductors but oppositeness as regards
to sign. These conditions to be secured by means of the well-known original
method of Dr. John Hopkinson, known as the "three-wire" system in which two
dynamos of equal voltage are run in series; and the two extreme conductors
connected to the terminals of the series, and the neutral conductor to a point in
the series between the two dynamos.
:
Secondly. The mains may be charged in a similar manner by the several well-
known developements of Dr. Hopkinson's method for instance any number of
transformers or motor-dynamos may be used in series or parallel series and con-
nections made in like manner from the three conductor mains to the extreme points
of the series and any point between: or a single transformer, or an inductive coil
may be employed, and connections made to the terminal points of the inductive
coil or of the secondary coil of the transformer and to any other point. I do not
restrict the invention to the use only of a condition of neutrality of the mid con-
ductor relatively to the extreme conductors, that is, of equality of potential
differences between it and the other two; as it may sometimes be of advantage to
have different potential differences on the two sides of the three conductor system.
Therefore I reserve the right of making the intermediate connection at any point
of the series or coil, necessary to obtain the required relation of the potential
differences of the mains. At the same time I am aware that the use of such an
unsymmetrical condition of the potential differences on the two sides of the
three-wire system, much modifies-the-working_of_the_invention-in-the-manner
indicated hereinafter.
Thirdly. The mains may be charged with alternating electromotive_forces
differing in phase: On one side of the three-wire system an alternating E.M. F.
may be impressed; and on the other side an E.M.F. of the same frequency, but
differing in phase.
The two currents of dissonant phase combine in the mid or neutral wire in the
manner well known. Or three E. M. F's and currents of different phases may be
combined on to the three wire mains.
These E.M.F's and currents of different phases to be generated in the usual
manner by a multiphase alternator.
At the substations or transforming points the aforesaid three-wire primary mains
are connected up to transformers in the manner indicated in diagram 1 Sheet I
herewith. Transformers, or groups of transformers coupled together either in
parallel or series, are connected across the two primary extremes as shown at A.

page_text: Their secondary coils are connected to the extremes of a system or network of
three-wire distributing or secondary mains, similar to the primary system of mains ;
which distribute immediately to the points of demand. These transformers or
groups would be generally of a capacity equal to the major part of the maximum
load. At B & C other transformers are connected up to the neutral conductor and
one of the extremes; and their secondary coils are coupled to the secondary mains
in a corresponding manner. These latter transformers are relatively small, being
designed to take the light day load.
The operation of the system is as follows:-
When the demand is in excess of a certain proportion of the maximum load, the
primary mains are supplied with current on the well-known three-wire principle;
that is the potential difference across the two extreme.conductors is equal and in
absolute parallelism, or in other words consonance of phase and period, to the sum
of the two potential differences between the neutral conductor and each of the
extremes. All the transformers connected are then actively employed, the small
transformers at B & C Sheet I acting also as regulators or equalizers maintaining
the equality of pressure on the two sides of the three-wire distributing maius.
When the load falls below the critical proportion the potential difference between
the extreme conductors of the primary mains is annulled by switching one of them
on to the same pole or terminal as the other. To enable this operation to be
performed with the requisite facility a special switch for the purpose controls each
primary circuit from the supply centre, so that the engineer there in charge may
instantaneously effect the change over so soon as he notes from the ammeters in the
circuit that the load has arrived at the critical value at which it is arranged the
change-over should take place. The critical point is determined by the total
capacity of the small transformers, as at B and C, on the circuit and it occurs
when the load is equal to this capacity.
The said annulling of the potential differences across the primary extreme
conductors relieves the primary coils of the large transformers as at A of electro-
motive force and the connection of the one extreme conductor to the same pole as
the other produces a relative reversal of current in the smaller transformers on
the side which is switched over;-that is in those transformers in connection
between the neutral conductor and the extreme which is switched over. This
reversal of current on one side of the three wire system annuls the potential
difference across the extreme conductors of the three wire secondary mains.
Thus the large transformers at A are completely thrown out of action being
relieved of E.M.F. on both primary and secondary coils. And as the electrical
pressure between either of the extreme conductors and the neutral conductor is
not altered or affected (excepting the case of unequal pressure on the two sides
of the three-wire system) either on the primary or secondary systems the requisite
continuity of supply and constancy of pressure is duly maintained.
The arrangement as described illustrates the general principles of my invention
in its application to continuous, alternating, and pulsating current systems the term
transformer being used in its broader sense to comprisé any transforming device for
use with any electric current. By the arrangement described, a single change only
is made at some convenient value of the rising or falling load. There is therefore
but one step obtained in the control of the transformer capacity in action: that is
from a given fraction to the full capacity or vice versa. This is sufficient to effect
a considerable saving of the electrical energy otherwise wasted in uselessly
magnetising the iron of the large transformers but in some cases it may be desirable
to follow the load curve more closely than by a single step. If it be found
competent to arrange the load on the two sides of the three wire distributing
network so that pressure on one side may be conveniently dispensed with for a
period; then with the same arrangement of mains and transforming elements, by
switching one of the extreme or outer conductors of the primary mains on to the
same pole or terminal as the neutral conductor, one of the small transforming
elements in each unit is thrown out of action; and the E.M.F. on the terminals

page_text: :
of the large elements is reduced to one half, meaning a greater reduction of the iron
losses therein. The available plant is thereby halved; and the constant loss in
same, reduced by a somewhat greater proportion one side only of the system being
supplied. Also by switching one of the said extreme conductors off contact all but
one of the small transforming elements of each unit are put out of action and one
third the normal pressure will be still available on the shut-off side of the three-wire
distributing system.
Further any number of changes of transforming capacity may be secured by the
developement and application of the invention to the case of multiple primary and
secondary mains in connection with sets of transforming devices arranged on the
general principles above indicated so that a changing or switching. over of the
component conductors of the primary mains at the supply centre shall vary
the E.M.F's, on both coils of particular transformers, in the manner required.
In alternating and pulsating current systems I secure any number of changes in
transformer capacity to suit the variations in load by charging the two sides of the
three-wire primary mains with E.M.F's of the same periodicity but differing in
phase, each step being obtained by an alteration in the phase difference. The
combined E.M.F. across the extreme conductors, will be then varied in accordance
with the said phase difference and the effective capacity of the large-transforming
elements connected across them is varied accordingly.
A perfect following up of the load variations by the varying transformer plant
in action can be effected by applying to the two sides of the primary three-wire
system equal and similar alternating electromotive forces adjustable in phase
relative to each other from consonance up to a phase difference of 180° or opposite-
ness. Then when these E.M.F's are in consonance no potential difference will
exist across the two extreme conductors of both primary & secondary systems and
therefore the large transforming elements are entirely out of action. By making
the phase to differ the E.M.F. across them may be gradually raised from nil to the
full working E.M.F. so that these transformers may be brought into action just
so much as is required by the actual load on the mains. The regulation of the loss
occurring in the transforming plant is therefore under perfect control by this method.
The adjustable difference of phase, I find can be best secured by using two
alternators, or an alternator with two sections, coupled mechanically by an adjustable
coupling which may be adjusted by hand, or automatically as required by the
variations of load.
In the practical application of my invention, the following considerations should
be observed:
-
The size of the smaller transformers as at B. & C. Sheet I will be deter-
mined from considerations of the load curve or diagram for the particular
area supplied by each also by the greatest probable difference of load or want of
balance, between the two sides of the three wire secondary network. The total
capacity of the transformer plant should be equal to double the greatest load that
is likely to come-on-either-side-of-the-three-wire-system.
It is generally to be preferred, in order to prevent the occurrence of idle
balancing currents in the secondary network, that the plant be arranged so that
each transformer substation is complete in itself, each containing the three elements
which may be said to comprise a complete transforming unit in the system, viz.:
a transformer, or group, of transformers, of large relative capacity as at A Sheet I:;
two smaller transformers or groups, as B & C Sheet I; the three elements being
connected up to the mains in the manner previously set forth and described. But
this is not a necessary condition; and where it can be foreseen that the balancing
currents will not appreciably affect the working of the mains, it may be found
convenient to separate the unit:--as for instance by using a lesser number of pairs
of small transforming elements than of large transforming elements distributing
them over the substations in suitable manner.
The large transforming elements should be designed generally for a high
efficiency at full load though if the rise and fall of the particular part of the load

page_text: -curve or diagram with which they are concerned, should be very gradual it may be
more advantageous to design them for an efficiency well sustained over a long
range of loads. The small transformer elements should be designed uniformly for
a good general efficiency over a full range of loads.
The size of the middle or neutral conductor of the primary mains will be
determined by the greatest proportion of load that it is decided shall occur before
the change over switch is operated. A further consideration affects this and the
size of the small transforming elements: In the majority of cases it may be found
advantageous that this conductor and the small trausforming elements during
heavy load shall take up the duty of supplying the unbalanced load on either side
of the three-wire system thus reducing the idle currents (if any) in the secondary
mains, and the output from the large transforming elements. One method by
which I secure this result is as follows:-The small transforming elements must be
designed with a slightly lower transforming ratio than the large elements and with a
greater internal drop of volts at full load. In any case this point should be observed to
prevent them being overloaded. Or a method by which better regulation would
be secured is thus:-At the supply centre the want of balance on the two sides of
the three-wire distributing network is exhibited quantitatively by the difference
between ammeters on each of the extreme primary conductors or directly by a
differential ammeter connected thereto. According to this difference the balance
of E.M.F. on the two sides of the primary mains is slightly altered or upset
towards the same side either by hand adjustment or automatically. The small
transforming elements on that side are thereby constrained to supply the
unbalanced load direct by transformation from the primary mains, and not by mere
equalisation of the output of the large elements: the load on the small elements on:
the other side is simultaneously reduced which assists the action.
The size of the neutral conductor as well as of the two extremes of the secondary
mains is governed by the usual considerations to be observed in distributing by the
three-wire system: unless the disposition of the transforming elements is such that
idle balancing currents may occur in these maius: in which case the probable
dimensions of such currents must be taken into consideration also.
The switching mechanism by which the change over operation is made may be
arranged to come into action automatically by the variations of load. But in most
cases as proper attendance is always and immediately available at a supply centre
it will be preferable not to complicate the apparatus thus: but to let the operation
be performed by hand by the engineer-in-charge. The switch must be designed to
minimise as much as possible the sparking resulting on breaking a high tension
current and the action must be rapid to prevent a fluctuation in the supply on the
one side of the three-wire system.
It must be understood in the use of the systems described that as the indications
of the load on any circuit from the supply centre are the complete integrations of
the loads on all parts of the circuit the regulation of the transformer capacity is
made to meet the average load, and not the load at any one section of the circuit.
If therefore an abnormal load should come on one spot, the transformer plant
supplying the section might become overloaded though the ammeters on the circuit
may not show that it is loaded up to the point at which the change over should be
made and further transformer plant brought into action. To provide against such
an event and the blowing of fuses and possible damage to transformers consequent
thereon, a greater number of substations should not be connected to one circuit than
this circumstance would warrant when considered in connection with the economical
disposition of the pilot or pressure indicating wires for the particular case involved.
Further the distributing or secondary network should be connected up as far as
convenient so that adjacent substations may take part of the abnormal load. For
compact districts permitting such connection this plan is the best and the substations
can be placed so that an evenness of pressure can be perfectly insured with a
secondary network formed of mains of moderate and economical section. Increase
of demand on the circuit may be met, either by laying down additional substations

page_text: without altering the secondary mains ; or by increasing plant in the existing
substations, and putting down feeders from thence to the points required.
As an absolute precaution against the risk of the plant in one substation being
overloaded by an abnormal demand, a system of connecting up the primary coils of
the transforming plant in series through several substations, may be used in con-
nection with the systems herein described. The transformers connected in series
must so far as their primary coils are concerned be designed as series transformers.
for a constant potential on the terminals of the series. The secondaries must be
designed to give the requisite pressure at the normal load of each: they are to be
connected up to the secondary network in the same way as for parallel working.
The network must be connected up and of somewhat larger section to permit of the
pressure equalising over it. Or in place of increasing the section of mains, or
connecting up, a tertiary winding preferably of many turns for a high tension may
be placed on each of the series transformers and connected all in parallel: this
tertiary circuit will then take the greater part of the flow of energy necessary to
preserve equality of pressure over the secondary network. The series circuits may
conveniently start directly from the supply centre, thus bringing them directly
under control for regulation, etc. An advantage of this series arrangement is that
high pressures may be employed in the primary series circuit without increasing the
difficulties of insulation in the transformers.. It is the more useful applied to
continuous current systems.
The application of the systems to continuous current systems must be generally
carried out on the lines described except where it is obvious these apply only to
alternating currents. A special feature is the method of exciting the field magnets
of the dynamotors. The large ones as at A in the diagramis can be most con-
veniently excited by a shunt winding across the secondary terminals. To insure
the proper starting of these dynamotors it may sometimes be desirable to assist the
field by a few series turns in the primary neutralised by an equal number of series
ampere turns in the secondary circuit. The smaller dynamotors at B & C in the
diagrams must be excited so that the field of one can be reversed when the change
over is made. The same method as employed in the larger dynamotors may be
In some cases it may be advantageous to run separate exciting circuits from
the supply centre exciting the dynamotors either in series or parallel. A compound
winding may sometimes be used with the shunt circuits across the primaries.
This question, requires to be considered in conjunction with the whole circumstances
of each particular case, so that no generally defined rules can be set forth. If
dynamotors requiring lead of the brushes are used the arrangement should be such
that the direction of rotation is not reversed.
used.
For the better description of my invention I attach hereto diagrams showing
various arrangements of the systems.
Sheet I illustrates the application of the invention to one set of circuits on one
dynamo machine :-
D is an alternator with two circuits_in_the_armature_which_may_he-connected-in
series or parallel: that is to say they may be connected so as to form a single
continuous path or circuit through the machine, or two parallels paths or circuits.
through the machine in the wellknown manner.
S is a switch by means of which the said two armature circuits may be thrown
into series or parallel with each other and the required change of pole simultaneously-
effected on one of the extreme conductors of the three wire mains. There are
several obvious methods and arrangements for performing the said switching opera-
tions in practice. That illustrated is a convenient diagrammic arrangement showing
what is required. It consists of three levers or pivotted conducting bars, with their
pivot ends in connection each with one of the conductors of the primary mains,
arranged sc that their outer ends may swing over a series of contacts. Two of the
levers, the one in connection with the mid or neutral conductor of the mains, and
either of the other two,-are forked or broadened out so as to cover two adjacent

page_text: contacts. Seven contacts are shown of which the two outer are blank or bearing
contacts only. Two of the others are connected to one of the four ends of the
armature circuits; and the remaining three ends each to one contact, in the manner
shown. In the position shown the extreme conductor a. is in connection with one
pole of the armature circuits, which are in series ;-the neutral conductor b. is
connected to the middle point of the combined series circuit of the armature; the
forked end of its lever serving to connect together two of the ends of the pair of
armature circuits so that these shall work in series :-and the extreme conductor c..
is connected to the opposite pole of the series.
By moving each lever one contact to the left the armature circuits are brought
into parallelism with each other; the two forked ends of the levers coupling them
thus; and the conductor r. is put on a contact in connection with a; its relative
polarity being thereby reversed. The required operation of switching out the
desired transformers is therefore performed; and the reverse operation may be
carried out by returning the levers to their original position.
All connections to measuring instruments, fuses and other controlling apparatus
are omitted from the diagram to simplify it.
The primary mains a. b. c. are shown feeding into five substations. In each
A represents a large transformer or group connected to primary extreme mains a.
and c. and secondary extreme mains d and f. B represents another transformer or
group connected to a and b; and e and f. C represents a similar set connected
to b and c, and d and e.
The dotted lines indicate portions of the secondary distributing network of mains.
In the diagrams on Sheet I the lettering is the same. Four single circuit
alternators are shown feeding in parallel on to a sectional omnibus bar, at the
extreme primary pressure. By means of the inductive coils K K consisting of
.single circuit transformers with connections to the mid points of their coils, a mil
or neutral bar is maintained at an electric potential midway between that of the
other two. From the omnibus bar three separate circuits lead out of the station
the conductors of each passing through switches at S. and ammeters at M. The
switches on the extreme conductors of each circuit, enable them to be thrown on
either pole of the dynamos, through the omnibus bars. The circuit on the right
supplies two substations in which the transformers at A are connected in parallel to
both primary and secondary mains but the primary coils of the transformers at B. B.
are connected in series through the two from 6 to a. and those at C. C. similarly
from b. to c. Their secondary coils are connected to the secondary distributing
mains in parallel in the manner described. The secondary mains should be
connected up between the substations as shown. The circuit in the centre supplies
one large substation. That to the left of diagram supplies two substations
containing each one large transformer at A A connected across extreme conductors
of the mains and one small transformer at B and C connected to mains a. and b.,
and e. and f.: and b. and c., and d and e. The secondary mains are connected up to
allow balancing currents to flow between the stations.
The arrangements shown in the diagrams apply equally to continuous current
applications.
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 is :-
1. The system, and modifications thereof, of distributing electricity in the form
of continuous, alternating, and pulsating currents of any kind, by means of a system
of primary mains feeding into a system or network of secondary mains through
transforming devices, which mains and transforming devices are arranged so that
an 'alteration or alterations in the condition of the electric potentials on the primary
mains shall have the effect of varying the effective capacity of the transforming
plant in action, while the electric pressure between the active secondary mains is

page_text: maintained constant; and thereby of securing control over the loss of electrical
energy occurring in the said transforming devices:-substantially as herein described
and set forth.
2. The use of generating plant arranged to yield the requisite supply of electrical
energy in the requisite forms and potentials to secure and effect the required
changes, continuously, or by steps, of electric potential condition in the primary
mains, with the objects aforesaid, in the manner and substantially as hereinbefore
described and set forth.
3. The use of switching, or similar mechanism, at the central station or at any
other point or points by which the requisite alteration of potential condition in the
primary mains may be effected; further the use of automatic switching mechanism
for effecting the said purpose; with the objects aforesaid substantially as herein-
before ascertained and described.
4. The use of coupled alternators, or alternators with two adjustable sections,
arranged to supply two E.M.F's adjustable relatively to each other in phase,
either by steps or continuously, by means either of an adjustable coupling of the
shafts or by the angular adjustment of the fixed field magnet system or of the fixed
armature of one of the alternators or sections, substantially as set forth with the
object of varying the potential difference across the extreme conductors of a system
of three-wire primary mains with the objects aforesaid.
5. The use of transforming devices such as alternating current transformers,
continuous current motor dynamos or dynamotors, rotary field transformers,
transformers for converting alternating currents into continuous and vice versa, etc.,
connected to a system of three or multiple wire primary and secondary mains in the
manner herein ascertained and described for the objects aforesaid.
6. The use and connection of what is herein designated complete transforming
units, comprising each a number of transforming devices, isolated in one substation,
or distributed among several, consisting of transforming devices connected to the
multiple-wire mains so as always to maintain electric pressure between certain of
the secondary conductors independantly of the annulling or change of electric
pressure made between certain other pairs of conductors similarly in both primary
and secondary systems; and of other transforming devices connected to the said
pairs of conductors between which change of electric pressure may take place
without affecting the pressure between those secondary conductors in which it is to
be continually maintained with the objects aforesaid substantially as herein set
forth and described.
:
7. The use and connection of the transforming devices in any substation, or some
of them, in series on their primary sides with others in other substations, for the
purpose of equalising the load over the substations substantially as herein ascertained
and described.
8. The system, and use thereof, substantially as described, in which the aforesaid
dispositions and arrangements of multiple-wire mains and-transforming-devices are
made but in which different electric pressures are used on opposite sides of the
three wire mains, or between analogous pairs of conductors on the two sides of any
multiple wire system of mains, and in which the change over operation is made, not
necessarily by switching one conductor of the primary on to the same pole as a
conductor on the opposite side, but by -switching the conductor on to a pole or
contact in the electrical condition of exact oppositeness to its own pole in respect
to the mid conductor taken as neutral between the two poles; or further by means
of a two way switch reversing the connections from the source of E.M.F. which
maintains the electric pressure between the neutral conductor and the said extreme
conductor for the objects aforesaid, substantially as described.
Dated this 3rd day of January 1894.
JAMES WHITCHER.