Improvements in Electric Distribution.
Year: 1891

page_text: Date of Application, 9th Oct., 1891
Complete Specification Left, 9th Aug., 1892-Accepted, 10th Sept., 1892
PROVISIONAL SPECIFICATION.
Improvements in Electric Distribution.
ARTHUR WRIGHT 26 Park Crescent Brighton Electrical Engineer do hereby
declare the nature of this invention to be as follows :-
:-
My invention has for its object the reduction of the cost of supplying electric
energy by alternate currents both in the actual distribution of electric energy and
in the cost of the means for distribution.
It is now well known that in the usual method of distributing electricity by
means of high tension alternate currents and transformers a very large percentage
of the energy produced is absorbed in magnetising the iron cores of the transformers
which are usually permanently connected to the supply station although the number
of hours per day during which any current is required from them, rarely exceeds 5
to 6 so that during the remainder the energy required to magnetise the transformer
is entirely wasted.
Now my improvements enable the waste to be minimised as much as desired, and
enables transformers to be only fully magnetised when any current is required of
them; during the remainder of the time they can be disconnected entirely from the
supply mains or made to take only a very small proportion of the energy generally
required to magnetise them. It is also known to designers of transformers that the
loss in the iron can be reduced by increasing the number of windings of wire round
the core, but as this generally increases the fall in volts between full and no load a
limit is very soon reached to the number of turns or length of copper. Now my
improvements consist in so designing the shape of the core and in supplying each
transformer on circuit with means for keeping the voltage at its terminals constant,
that a much greater length or number of turns of copper can be used. The current
carrying capacity of the wires and circuit are thus no longer limited by the fall of
voltage in them, but only by their reaching too high a temperature which heat
limit in practice, enables them generally to carry two or three times what the
(drop in volts) limit would do.
My improvements consist essentially therefore of means for diminishing the loss
of energy in magnetising the iron core of transformers;-in designing the
transformer so that very little iron may be used, and in supplying means for
keeping the voltage of transformers on circuits constant when their resistance and
the varying current carried would otherwise cause a great difference of voltage.
The following description will enable any electrician accustomed to alternate
currents to understand my invention :-
:-
I provide each transformer with a switch whose motive power may be electrical
or mechanical worked by a sensitive fine wire electro magnet or solenoid connected
in series with the secondary circuit, so that when one or more lamps are turned on
in the secondary circuit, a small current passes through the magnet coils. This
switch on being thus acted upon, either cuts out a very large resistance or an
impedance coil connected between the primary and the supply mains, or bridges
over a break between these two; it also short circuits the fine wire electro magnet
or solenoid in the secondary circuit;-thereupon the full tension is put across the
primary and generates the normal tension in the secondary which now passes
sufficient current through the one or more lamps and through another magnet or
solenoid wound with thicker wire which is also connected in series with the
secondary to hold the switch in its proper position as long as any lamps are

page_text: connected up. On all the lamps being turned off the thick wire magnet ceases to hold
up the switch, which on being released removes the short circuit from the primary
resistance impedance or break, also that on the fine wire magnet in series with the
secondary, the switch is then again in position ready to act whenever a lamp is
turned on. In the other method above described where, when no lamps are on the
secondary there is a complete break or disconnection between the primary of the
transformer and the supply mains, I provide a small local battery proximity to
the switch and connected to the lamp circuit through the fine wire magnet, so that
on a lamp being turned on a circuit is formed for the battery to pass a current
through the magnet coils round the lamps and back to the battery, this current
actuates the switch which joins up the primary to the supply mains also the
secondary to the lamp circuit and breaks by a special contact bridge the local
battery circuit. A thick wire magnet holds the switch in position as before as long
as any lamps are on. In some cases it may be well to interpose a suitable
condenser between the secondary and the lamp circuit instead of a break to prevent
the local battery running itself down through the low resistance of the secondary.
This would enable one bridging piece of the switch to be dispensed with and if the
circuit of the local battery were made to go through a depositing cell or motor
meter which could be made to register the number of lamp hours the lamps had
consumed another bridging piece could be done away with thus leaving the switch
only to bridge the gap between the primary and the supply mains. From the
above it will be seen that the energy absorbed in the transformer core, when no
lamps are turned on, can be rendered as small as desired without interfering with
its always being ready to supply energy when called on. The above switches can
be provided with a hand switch to be used in case the automatic action fails.
In order to diminish the loss in the iron while the transformer is at work and to
diminish the cost of construction of the same I prefer to make it up of a number of
sheet iron strips of suitable length and breadth built up so as to form a rectangle
or polygon, whose plane is parallel to the plane of the strips, and to bind or bolt
the ends of the strips together at the corners. The number of strips built up
together may be varied to give the necessary amount of iron section. The coil
windings can be wound on all of the sides or some of them and a transformer of any
given out-put can be made from the same size of sheet iron cutting. In order to
still further diminish the amount of waste in the iron, I prefer to make the space
occupied by the coils as small as small a compass as desired by using finer wires for
a given out-put than is customary in transformer design, thus having a resistance
which would under ordinary conditions produce a great variation in the tension at
the transformers secondary terminals but which variation I correct by the following
device which is also applicable to the maintenance of constant potentials in circuits
where otherwise the resistance would cause a great variation as the current
traversing them varied.
Near the point where it is necessary to maintain constant potential I introduce
an impedance or resistance coil, whose core or contact tongue can be moved by
a motor so as to introduce more or less impedance or resistance in the circuit;
this motor is worked by simply a shunt or series circuit from the mains, or a
shunt winding that combined with a few turns of thick wire through which the
main current passes and its motion is resisted by a spring, weight, or other suitable
force. The resistance can either be directly varied by the tension altering, or
indirectly by making the variation of the resistance to only occur on the tension
altering. By this means it is quite practicable to make transformers which under
ordinary conditions of working, would vary ten per cent. between full and no load,
keep a practically constant potential on a circuit supplying lamps and as is well
known transformers designed to have a 10 per cent. drop can be made to have a
very much smaller waste in the iron than in transformers where the drop is limited
to 2 or 3 per cent.
One great advantage of an impedance coil varied by a commutatorless alternate
current motor such as designed by myself and Alderton and Philpot in 1889 is that

page_text: no moving contacts of any sort are wanted and by compound winding the fields of this
motor, perfect regulation can be effected for any drop in transformers or circuits.
Dated this Ninth day of October 1891.
COMPLETE SPECIFICATION.
Improvements in Electric Distribution.
1, ARTHUR WRIGHT, of 26 Park Crescent, Brighton, 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 has for its object the reduction of the cost of supplying electric
energy by alternating currents in the cases wherein transformers are employed. It
is now well known that in the usual method of distributing electricity by means of
high tension alternating currents and transformers a very large percentage of
the energy produced is absorbed in magnetising the iron cores of the said
transformers. These are usually permanently connected to the supply station
although the number of hours per day during which any current is required of them
rarely exceeds 5 to 6, so that during the remainder of the 24 hours the energy used
to magnetise the transformer is wasted.
Now my improvements enable the waste to be minimised, and enable transformers
to be fully magnetised only when current is required of them. During the
remainder of the time they can be disconnected entirely from the supply mains or
made to take only a very small proportion of the energy that would otherwise be
required to magnetise them.
My improvements relate then to a method of and apparatus for diminishing the
loss of energy in magnetising the iron cores of alternating current transformers
used in a system of electric distribution.
My invention in so far as it relates to the method of diminishing the said loss of
energy consists in automatically introducing into and removing from the main
circuit (that is to say that part of the circuit where the primary of the transformer
is connected with the supply mains) a break or a resistance (the said resistance
being real and or virtual) as may be required.
My invention in so far as it relates to the apparatus consists in the employment
of a device which I shall hereinafter term a magnetisation economiser.
I
Having now described my invention in general terms so as to define its scope
shall in order that it may be easily understood proceed to explain by reference to
the accompanying sheets of drawings how it may be practised or carried into
effect. I shall first of all describe a case in which a resistance is introduced and
removed.
In Figure 1, P is the primary coil and S the secondary coil of an alternating
current transformer and M, M' are the mains with which P is connected. m, m³ are
the leads supplying the current to the lamps and with which S is connected.
L, L are lamps bridging between the leads m, m³ in the usual manner. F, F¹ are
solenoids arranged in series in the lead m, the coil of F having a very large number
of turns and that of F having a few turns of wire of large section. The cores f,f
of these solenoids are connected at the points c, c¹ to the switch lever A C turning
upon the centre D. To the said lever are attached double spring contacts G
and H the contact points of which g, g' and h, h' make contact as will be
hereinafter described with the contact points g³, g' and h³, h³. At the point B in
the main circuit there is a break which in this case is bridged across by an
impedance coil or high resistance R.
To understand the action let us assume that the parts are in their normal
position, namely that shown in full lines in the figure, and that none of the lamps

page_text: are turned on. Under such circumstances it will be understood that no magnetisation
of the core of the transformer is required and that none will be required until
one or more lamps are turned on. During this period which I shall hereinafter
refer to as the period of rest there is very little magnetisation of the transformer
core on account of the high resistance offered by R to the passage of the 5
current. Suppose now that the lamps begin to be turned on. A small current
will pass through the solenoid coils of F and F. This small current will
cause the coil to attract its core and pull down the lever AC until the
contact points 9, g' are brought into contact with the points g³, g³ respectively,
and the contact points h, h' are brought in contact with the contact points /³½³ 1
respectively, this new position being shown in dotted lines. This will cause the
impedance coil R and the solenoid F to be short circuited the effect of which
will be that a large current will now pass and the core of the transformer be
fully magnetised. At the same time this short circuiting will be maintained by
the pull of the solenoid F¹ which remains in the circuit and which as has 1
already been mentioned is of a small number of turns of thick wire. When the
period of rest again arrives and the lamps are switched out the current will
cense to flow through F", its core will cease to be attracted, and the lever A C
will rise to its normal position and G and H break contact, so that R and F
will be again cut into circuit and ready when next a lamp is turned on to act 2
as before. It will thus be seen that during the period of rest the transformer
core is only magnetised to an inappreciable or minimum extent and that a great
saving of electrical energy is effected.
In actual practice prefer to short circuit coil R by means of G a little
before I short circuit F by means of H. This I effect by using elastic spring
contacts and extending them to a relatively lower position in the case of G.
Figures 2 and 3 illustrate an actual form of apparatus acting upon the
principle just described, the said apparatus constituting the best form of
magnetisation economiser, which I have devised up to this date, when it is a
resistance which has to be inserted and removed as before mentioned.
3
In these figures J represents the base of the magnetisation economiser and K
an upright or support to which certain parts are attached as will presently bo
seen. To the said base is fixed the-coil N which in this case corresponds with
and takes the place of not only the coil R of Figure 1 but also (in so far as
its function is concerned) the solenoid coil F of that figure. Within the said 3
coil N is a fixed piece of iron n preferably laminated. is a bracket attached
to the upright K and serving to support the double coil O. The said bracket k
also serves to support the swing piece Q. This swing piece which corresponds
with the switch lever of Figure 1 bears at its upper end the bridging contact
piece which serves to connect the two contact tongues k¹ and so to short 4
circuit the coil N when required. The swing piece moves on the centre 9' 9' is
a core upon which the coil q is wound, the said core and coil being within the
double coil O herein before mentioned and capable of movement within the said
double coil upon the centre g¹, the arrangement being somewhat similar to the well
known arrangement existing in what is known as the Siemens dynamometer and
such that when a current passes movement of the said core g³ with its coil q* will
take place within the double coil O in the direction shown by the arrows. From
the said core a rod preferably of ebonite passes up to the bridging piece 9 and a
similar rod preferably of ebonite passes downward from the core to the iron bob-
piece 2. The normal positions of the parts constituting my magnetisation 5
economiser are as shown in Figure 3.
Figure 4 is a diagram showing the connections of the parts represented in
Figures 2 and 3, from which it will be seen that the coil N is short circuited by
the bridging piece 9 connecting the contact tongues. The double coil O will
be seen to be in the secondary circuit and the coil to be in a shunt therefrom.
To understand the action let us assume that the parts are in their normal
1-osition se that the coil N is in series with the primary winding of the transformer

page_text: and so that there is but little magnetisation of the transformer core.
Now let a
lamp or lamps be switched on. Current will be required from the secondary and
full magnetisation of the core will be required. The switching on of a lamp will
complete the secondary circuit, already closed through the high resistance g³ though
in a way to pass but little appreciable current, and a small additional current will
flow through the coil N so that the iron piece n will repel the iron bob-piece and
cause movement in the direction of the arrow. This will bring the bridging contact
piece q into contact with the tongues so as to short circuit the coil N. This
will cause the full voltage to be produced in the secondary circuit and the current
now flowing through the double coil will act upon the core 72 and coil so as to
keep the swinging piece in its new position and maintain the short circuiting of the
coil N as long as current passes. When the period of rest again arrives and the
lamps are turned out so that current no longer continues to flow through the
secondary circuit the core q' and coil g' will no longer be acted upon by current in
the double coil and the swing piece will return to its normal position. The
coil N will again be no longer short circuited but will be in series with the primary
coil and prevent loss by unnecessary magnetisation of the transformer core.
I have now described the automatic introduction and removal of a resistance
and shall proceed to show how a break in the circuit may be introduced or
removed instead of such resistance. For this purpose I refer to the diagram
Figure 5 which corresponds in many respects with Figure 1. It differs however
therefrom mainly in that the break B has no resistance R therein and that the
current required to actuate the switch lever A C is furnished not from the
transformer but from a separate battery T in the secondary circuit. V is a
condenser also in the secondary circuit. W is a third contact similar to those
represented by G and H but placed on the other side of A. C so that the movement
which closes circuit at G and H opens circuit at W and vice versa. In other
respects this diagram is similar to that shown in Figure 1, but its action differs and
is as follows. When a lamp is switched on there is a path for the current of the
battery through W, F and F. A pull is produced upon the core f and the switch
lever is brought down as before mentioned so that & bridges across the break B
and completes circuit through the primary, and the transformer core is magnetised
so that the necessary current traverses the secondary circuit. The solenoid F' now
retains the lever in its lower position as before, the solenoid F being short circuited.
The function of the condenser V is to prevent the battery T running down through
the secondary coil of the transformer and as it permits the passage of an alternating
current freely its interposition does not interfere with the passage of the current
in the secondary circuit. In cases however in which the regulation of the lamp
circuit might be interfered with it is desirable to add yet another contact similar
to and on the same side of the lever as G and H for the purpose of short circuiting
the condenser. The condenser V interposed in the secondary circuit obviates the
running down of the battery through the secondary coil of the transformer but it
will be obvious that when the lamps are switched on the battery might run down
through the lamps but for its circuit being opened by the contact W.
It will be seen that Figure 5 is diagramatic and that it corresponds with
Figure 1. I do not show any piece of apparatus bearing the same relation to
Figure 5 which the apparatus shown in Figures 2 and 3 bears to the diagramatic
Figure 1 for the reason that I have not constructed any magnetisation economiser
in a similarly compact form. I have not done this because I find that the group of
electrical devices shown in Figure 5 gives sufficiently good results. Any competent
engineer however could easily put the device shown in Figure 5 into a more
compact form (just as I have put the device shown in Figure 1 in the compact
form shown in Figures 2 and 3) should such be desired. It will be obvious to every
electrical engineer that the number of cells arranged in series in the battery
symbolically illustrated in Figure 5 will depend on the resistance of the lamps L.
In arranging the contact points of W care must be taken not to break the battery

page_text: circuit too soon as otherwise the short circuiting of B and F might not be properly
effected.
It will be seen that my invention is not applicable to the case wherein the
transformers are connected in the main circuit in series.
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 improvement in electrical distribution which consists in the method of
diminishing the loss of energy in magnetising the cores of transformers by auto-
matically introducing into and removing from the main circuit either a break or a 1
resistance, as the case may be, substantially as and for the purpose set forth.
2. The improvement in electrical distribution consisting in the employment of a
magnetisation economiser substantially as and for the purpose set forth.
3. The improvement in electrical distribution consisting in the employment of
the specific form of magnetisation economiser shown in Figures 2 and 3.
Dated this 9th day of August 1892.
1