Improvements in the Method of and Means for Regulation of Alternating Current Systems.
Year: 1897

page_text: Date of Application, 23rd Nov., 1897-Accepted, 14th May, 1898
COMPLETE SPECIFICATION.
Improvements in the Method of and Means for Regulation of
Alternating Current Systems.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of this
invention (which has been communicated to us from abroad by Charles P.
Steinmetz, of Schenectady, in the County of Schenectady, State of New York;
United States of America) and in what manner the same is to be performed. to
be particularly described and ascertained in and by the following statement:-
It is known by electricians & disclosed for instance in the Specification of the
American Patent granted to Lamme No. 582131 & British equivalent No. 11148
of A.D. 1897 that the phase relation between current and electromotive force in
an alternating current circuit may be modified by electro-dynamic phase modifiers,
resembling in general construction the synchronous machines now used for motors
and other purposes, by properly regulating the field strength of the phase modifier
or otherwise, and it has also been shown that in this manner the evil effects of self
induction in an alternating circuit may be overcome or compensated, and that
constant potential or constant current may be maintained in the regulated circuit,
together with other desired ends.
The present invention relates to the subject of phase modification, and phase
modifiers such as have been previously described are made a part of this invention
in certain new combinations.
The invention comprises a system of distribution of flexible character, such that
the desired potential or current conditions for proper working of the translating
devices may be maintained in part of an alternating current circuit, or in the
different sub-circuits or working branches of such a system irrespective of changes
of load and of variations of potential on the feeding mains, or, more generically,
at the source of energy supplying the circuits or portion of a circuit where regula-
tion is needed. Regulation is effected by modifying the phase relation of current
and electromotive force, hence one important element of the invention comprises
a phase modifier capable of modifying in the necessary manner the phase relation
at the point where regulation is to be secured. The phase modification may be
secured by any apparatus which will cause the current or electromotive force
waves to lead or lag relatively to each other, though for practical work our corres-
pondent recommends the synchronous machines referred to above as preferable
to all other phase modifiers now known to him.
The invention also contemplates restricting the action of the phase modifier to
such portion or portions of the system as demand regulation,. for by so doing the
phase control instead of extending its influence over the entire system between
the modifier and the generator, is localized, forming an effective means of regula-
tion at the point where regulation is needed, and permitting independent regulation
of different portions of the same system. Hence a second element of the invention
is a localizer restricting the influence of the phase modifier, and forming, as it is
termed, a flexible connection between different portions of the system, between

page_text: which the potential may vary within considerable limits. The localizer may
consist of any one of a number of known sources of out-of-phase waves of current
or electromotive force, though our correspondent prefers to use an artificial
inductance, especially on constant potential circuits.
This feature of this invention, which may be tersely summed up as localized
phase modification for purposes of regulation, finds a wide range of practical
application. For example, assume a long power system supplying electrical energy
to a number of sub-stations from which extend working circuits in which the
energy is utilized for lights, motors or other purposes. In ordinary alternating
systems of this character there will exist considerable difference of potential on
the feeding mains at the different stations, and the fluctuations of potential will
be irregular under different conditions of load, so that any method of central station
regulation for the entire system is impracticable. By the present invention each
sub-circuit becomes independently regulable. The potential may rise and fall
on the feeding mains, but in spite of such variations a constant potential or con-
stant current, or any other condition may be maintained in the working sub-
circuits.
In a similar manner when it is desired to run motors and lights in branches
from a single circuit, the fluctuations of potential due to the motors can be
compensated for, and the lamps may be made to burn properly.
When an artificial inductance is used as the localizer, it acts to consume or
supply any difference of potential between the regulated and feeder circuits
according as the current lags behind or leads the electromotive force, and it also
restricts the influence of the phase modifier. For example, assume that the
potential on the mains is too high, then if the phase modifier be regulated so as
to cause the current to lag behind the electromotive force, the self-induction due
to the inductance acts in opposition to the impressed electromotive force and lowers
the potential in the sub-circuit; while on the other hand, if the current is made
to lead the electromotive force the self induction will act in a contrary manner
to raise the potential.
A further feature of the invention consists in rendering the desired regulation
automatic by regulating the action of the phase modifier in the above described
local circuit by a responsive device connected in the regulated circuit in such
manner as to preserve automatically the desired potential or current conditions.
This responsive device preferably consists of a magnet coupled in shunt or
series with relation to the localized sub-circuit which by means of a motor-
mechanism will so control the phase modifier as to make the current lag behind or
lead the electromotive force. The invention claimed is not however limited to
this feature riz.: the use of such an automatic regulator in a localized portion
of an alternating system, since, so far as our correspondent is aware, it is entirely
novel to regulate a phase modifier on a constant potential circuit of any character
by an automatic device responding to changes of potential in the circuit.
The foregoing description outlines in a general manner the prominent features
of the present invention though it includes other features as well, which will be
described hereinafter and pointed out in the claims.
In the accompanying drawing which illustrates the invention in diagram applied
to an alternating current distribution system. A represents a source of alternating
currents, here shown as a single phase alternator, though it is to be understood
that the invention is equally applicable to all alternating systems whether single-
phase or multiphase. From the generator there extend feeding or supply
mains m m which ordinarily will contain no translating devices, but serve to feed
alternating currents to sub-stations where such currents will be transformed to a
lower potential by converters T T T and supplied to sub-circuits containing
translating devices. One such sub-circuit c d is shown leading from the con-
verter T in which are coupled lamps 7 and a motor M. Connected with the sub-
mains ed together with these translating devices is shown a phase modifier S of
the synchronous type, whose armature is connected in a shunt across the sub-

page_text: mains c d and whose field or inducing member is excited by a direct current,
supplied from a separate exciter E. This separate exciter is series wound, and
while the exciting current so furnished may be regulated in a variety of ways there
is illustrated for this purpose a mechanism for shunting a portion of the field coils
of the machine. This mechanism comprises a switch aring pivoted at ', and
connected electrically to an intermediate portion of the field winding of the exciter
in such manner that when the arm is retracted by a spring the shunt circuit
is broken and the field strength of the exciter is at its maximum. The arm g,
however, may be brought into engagement with a contact n so as to shunt a
portion of the field winding of the exciter when it is desired to reduce the exciting
current. To actuate the arm a pivoted lever i is provided which is adapted to
be moved in one direction by a retractile springs and in the other direction by
the core of a coil C wound as a solenoid, and coupled in shunt across the sub-
mains ed. The action of this mechanism will be readily understood. When the
potential of the sub-circuit rises above the normal the field strength of the exciter,
and consequently the current supplied to the phase modifier, is weakened, the
reverse action taking place when the potential in the sub-circuit falls below the
normal, so that by intermittently making and breaking the shunt at the contact n
the phase modifier is so regulated as to cause the current to lead or lag in the
sub-circuit according as it is desired to raise or lower the potential. A resistance R
is shown shunting the contacts between arm g and fixed contact n to reduce the
sparking at this point.
To localize the phase modification secured by the machine S an artificial induct-
ance similar to an ordinary reactive coil and having an adjustable magnetic core I'
is coupled in series with one of the sub-mains.
Instead of this inductance other sources of out-of-phase waves of current or
electromotive force may be used in combination with a suitable phase modifier
in the sub-circuit.
With the arrangement described the inductance restricts the action of the phase
modifier to the sub-circuit ed, and together with the phase modifier regulation
the potential in the sub-circuit is regulated in such manner as to satisfactorily
compensate for any fluctuations of potential in the feeding mains. This result
is accomplished inasmuch as, the electromotive force due to the self induction
of the inductance being always 90° behind the current in the sub-circuit, it becomes
possible by modifying the phase relation of the current and electromotive force
waves in the sub-circuit to make the electromotive force due to the self-induction
either to assist or oppose the impressed electromotive force according as a rise
or drop of potential in the sub-circuit is desired. In other words the inductance
consumes any surplus of potential or supplies any deficiency of potential at the
secondary terminals of the transformer other than that which is required in the
sub-circuit. The inductance is also made capable of regulation in amount by
providing the adjustable core I', or other equivalent means, so that the highest
degree of efficiency may be gained. If the lamps in circuit are few the inductance
should be made considerable, while if the number of lamps is increased the
amount of inductance may be diminished.
With this arrangement a constant potential in the local circuit can be main-
tained. Indeed it may not be necessary in all cases to regulate the phase modifier S,
since a small drop of potential in the circuit will alter the relation between the
counter electromotive force developed in the machine and the impressed electro-
motive force, so that a larger leading current will flow in the machine, which will
tend to raise the local potential, and in like manner a small increase of the local
potential causes a larger lagging current to flow in the machine tending to keep
the local potential down. It is also obvious that the self-induction of the trans-
former will, to a certain extent, supplement the inductance I, and in some cases
the self-induction of the transformer may intentionally be made large enough
to make a special inductance unnecessary.
The inductance I can be placed in

page_text: either the primary or secondary branches of the transformer, or in fact at any
point between the phase modifier and the feeding mains.
At the right of the drawing is shown a second sub-circuit connected with the
feeding mains through a transformer T2. In this sub-circuit ef are shown trans-
lating devices in series so that a constant current in the sub-circuit is desirable.
In this case the armature of the synchronous machine S may be coupled in series
with the load, while the inductance I shunts the load. To excite the field of the
synchronous machine there is provided a separate direct current generator E' which
is regulated automatically in response to changes of current, by a coil in series
with the lamps. The exciter may be regulated in a number of ways, many of
which are well known. For this purpose a resistance P is shown in the external
circuit of the machine more or less of which is brought into circuit to regulate
the current exciting the field of the machine S by a contact arm p, the arm being
adapted to be moved in one direction by a spring o, and in the other by the core
of the coil C'. If the current in the sub-circuit becomes too small, resistance is
cut out of circuit, thereby strengthening the field of the synchronous machine,
while if the current in the sub-circuit rises above the normal a reverse action takes
place. In this way a constant current will be preserved in the circuit at all times.
Having now particularly described and ascertained the nature of the said inven-
tion (as communicated to us from abroad) and in what manner the same is to be
performed, we declare that what we claim is:-
1: The combination in an alternating current system, of a source of out-of-phase
waves of current or electromotive force between the feeding mains and a working
sub-circuit or branch of the system, and a phase modifier in such sub-circuit.
2. The combination in an alternating current system, of a regulable phaso
modifier in a sub-circuit or branch of the system, and a localizer restricting the
influence of the phase modifier from other portions of the system, as set forth and
for the purpose described.
3. The combination in an alternating current system, of a phase modifier in a
working sub-circuit or branch of the system, and an inductance for localizing the
action of such phase modifier, as set forth.
4. The combination in an alternating current system, of a source of out-of-phase
waves of current or electromotive force between the mains and a sub-circuit of the
system, with a phase modifier in such sub-circuit and a regulator therefor such
that the current in such sub-circuit may be caused to lead or lag behind the electro-
motive force.
5. The combination in an alternating current system, of a source of out-of-phase
waves of current or electromotive force between the mains and a sub-circuit of the
system, with an electro-dynamic phase modifier comprising a conductor movable
relatively to a magnetic field, and means for regulating the phase modifier, as
and for the purpose set forth.
6. The combination in an alternating current system of an inductance for
localizing a sub-circuit or portion of such system, and an electro-dynamic phase
modifier comprising a conductor movable relatively to a magnetic field for modi-
fying the relation of current and electromotive force in such regulated portion
of the system and means for regulating the phase modifier so as to cause the
current to lead or lag, as set forth.
7. The combination in an alternating current system, of an electro-dynamic
phase modifier of the synchronous type regulable for modifying the phase relation
as desired in a sub-circuit or portion of the system, and an inductance serving as
a localizer for restricting the influence of the phase modifier, as set forth.
8. The combination in an alternating current system, of a phase modifier and an
artificial inductance for localizing the influence of the phase modifier to a sub-
circuit or portion of the system requiring regulation, one connected in series and
the other in shunt with the load, as set forth.
9. The combination in an alternating current system, of a phase modifier and

page_text: a source of out-of-phase waves of current or electromotive force acting as a localizer
to restrict the influence of the phase modifier, and meaus for regulating the
localizer, as set forth.
10. The combination in an alternating current system, of an artificial inductance
between the feeding mains and a sub-circuit or regulated portion of the system,
with means for regulating the inductance and a phase modifier such as above
referred to in the sub-circuit and means for regulating the same so as to cause
the current to lag or lead as desired, substantially as above set forth.
11. The combination in an alternating current system, of an artificial inductance
in series with the load on a sub-circuit of the system with an electro-dynamic phase
controller of the synchronous type in shunt to the load on such circuit, and means
for regulating the counter electromotive force of such phase modifier with relation
to the impressed electromotive force, substantially as described.
12. The combination with the mains of an alternating system, of an inductance
between said mains and the translating devices, and an automatically regulable
phase modifier such as above described and adapted to control the relation of
current and electromotive force in the said devices, substantially in the manner
herein set forth.
13. The combination in an alternating current system of a phase modifier and
localizer acting respectively to modify the phase relation of current and electro-
motive force in a sub-circuit or portion of the system, and to restrict the phase
modification from other parts of the system, and an automatic regulator for the
phase modifier maintaining the desired potential or current conditions, as set
forth.
14. The method of regulating an alternating current distribution system which
consists in modifying the phase relation between current and electromotive force
in a sub-circuit or portion of such system requiring regulation, and localizing
the influence of such phase modification from other portions of the system, as
set forth.
15. In an alternating current system. the method of regulation which consists
in localizing a sub-circuit or circuits from the feeding mains by a source of out-of-
phase waves of current or electromotive force, and modifying the phase relation
in such sub-circuit or circuits in such manner as to maintain the desired potential
or current conditions, as set forth.
16. The combination with alternating mains of two or more sub-circuits supplied
from such mains, regulable artificial inductances in' said sub-circuit and phase
modifiers connected with such sub-circuits controlling the relative phase of electro-
motive force and current in such sub-circuits.
17. The combination with alternating mains of two or more sub-circuits supplied
therefrom, regulable artificial inductances in said sub-circuits and regulable phase
modifiers connected with such sub-circuits and controlling the relative phase of
electromotive force and current in said sub-circuits.
18. The combination with alternating mains of a sub-circuit supplied therefrom
and a regulable artificial inductance in said circuit and a phase modifier controlling
the relative phase of current and electromotive force in said sub-circuit.
19. The combination with alternating current mains of a sub-circuit supplied
from such mains and an artificial inductance in such sub-circuit and a phase
controller connected with such sub-circuit and controlling the relative phase of
current and electromotive force in the sub-circuit.
1
1007
Dated the 23rd day
UL
mber 1807.
For the Applicants,
J. C. CHAPMAN,
Chartered Patent Agent, 70, Chancery Lane, London, W.C.