Improvements in Self Regulating Dynamo Electric Generators.
Year: 1886

page_text: Date of Application, 18th Dec., 1886
Complete Left, 19th Sept., 1887
Complete Accepted, 17th Dec., 1887
RESERV
Improvements in Self Regulating Dynamo Electric Generators.
We ROBERT PEROY SELLON Electrical Engineer WILLIAM MORRIS MORDEY
Electrician and CHARLES EDMUND WEBBER Major General R.E. C.B. all of Victoria
Works Belvedere Road in the County of Surrey do hereby declare the nature of
this Invention to be as follows:-
This Invention has reference mainly to alternate current electric Generators and is
for improved means of jobtaining self regulation of the current or electro motive
force It is also in part applicable to continuous current generators.
In alternate current generators when it is required to maintain the condition of
constant difference of potential either at the terminals of the Generator or at some
distant point of the mains we excite the field magnet or magnets partly by any of the
usual known or other suitable means such as any separate source or by means of one
or more coils or portions of the armature conductor provided with a commutator for
the purpose-Or by the commuted secondary current of a transformer the primary of
which is a shunt on the terminals or mains-Across some portion of one of the main
Conductors or resistance placed in the main circuit we take a shunt or derivation
which is connected by means of a Commutator and brushes in the manner usual in
correcting or commuting alternate currents with a separate coil on the fields or with
the initial exciting circuit already referred to. The shunted and commuted current so
obtained is employed to strengthen the fields and as it is proportional to the main
current it is by suitable proportioning of the machines enabled to maintain a constant
or such a rising or falling difference of potential as is required. For constant current
working this shunted and commuted current may be made to exercise a demagnetizing
effect.
This principle of taking a shunt from a portion of the main for the purpose of supplying
suitable correction is applicable to continuous current generators and we employ it for
the purpose of adapting compound Dynamos to meet the requirements of different
circuits that is to say to make their "characteristics" suitable to the circuits on
which they work. For this purpose we wind the series coil of the fields to more than

page_text: the required strength and then regulate it to the circuit by placing it as a shunt
across a resistance placed in one of the main Conductors.
When a separate excitor is employed the current shunted and commuted from a
portion of one of the main Conductors or from a resistance placed in the mains is
passed through the field coils or through a separate coil or circuit of the excitor.
In this case the initial excitation may be obtained from the separate excitor the
correcting excitation being produced simply by augmentation of the field current of
the excitor in the manner indicated.
Or the initial excitation of the alternate current generator may be obtained from
the separate excitor the initial field of which is obtained from the secondary of a
transformer the primary of which transformer is a shunt on the mains or terminals.
On the whole excitation may be derived from the separate excitor the fields of which
are magnetized by the commuted current from the secondary circuit of a transformer
the primary of this transformer being composed partly of a shunt on the mains or
terminals and partly of a Conductor placed in the main circuit.
Or the fields of the excitor may be magnetised directly from the alternate current
generator; the initial excitation by a shunt from the mains or terminals, the correcting
excitation by a shunt from a portion of the mains or from a resistance placed in the
mains in the manner above described.
In using the current shunted from the ends of the resistance in the main the
Commutator is arranged as in ordinary commutation of alternate currents and is not
a Collector to merely direct into the magnetizing circuit the alternate pulsations of
current which are already of one direction.
Instead of shunting a fraction of the main current from a portion of the main
conductor or from a resistance placed in the main conductor for the purpose indicated
we may commute the whole current for this purpose but prefer only to take a portion
of it shunted from the main conductor in the manner described.
Dated this 18th day of December 1886.
J. HENRY JOHNSON,
Agent for the said Robert Percy Sellon,
William Morris Mordey, and
Charles E. Webber.

page_text: Improvements in Self Regulating Dynamo Electric Generators.
We ROBERT PERCY SELLON Electricial Engineer WILLIAM MORRIS MORDEY
Electrician and CHARLES EDMUND WEBBER C.B. Major-General R.E. all of Victoria
Works Belvedere Road in the County of Surrey 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 mainly to alternate current electric generators and is
for improved means of obtaining self-regulation of the current or electro motive force.
It is in part applicable to continuous current generators--The accompanying Drawings
illustrate diagrammatically various ways in which we may carry our our Invention as
hereinafter described and explained. In all the figures, similar parts are as far as
possible indicated by similar letters of reference.
In Figure 1, A' is the armature of an alternate current generator, A is the collector,
and F is the field magnet or magnets of the same, C is a commutator placed on the
shaft of the alternate current generator.
M M are main conductors connected to the
collector A. R is a resistance placed in the main circuit. TT are lamps or other
translating devices-a, a and b b, are respectively the initial and correcting coils or
windings of the field magnet or magnets F, according to this Invention. The
collector A is shewn as consisting of two rings a² a connected with the terminals or
ends of the conductor on the armaturo A¹-Contact is made with these rings by two
brushes a a³ which receive the alternating current. The commutator C, is shewn in
its simplest form as consisting of two contact pieces e³ ³ with brushes c³ ³ resting
upon them. It will be understood that the number and arrangement of the contact
pieces depends upon the number of alternations of current occurring during each
revolution, also that in applying our Invention to alternating current machines in
which the current is generated in the fixed or stationary portions the arrangement of
rubbing contact A is not required.
In alternate current generators when it is required to maintain the condition of
constant difference of potential, either at the terminals of the generator or at some
distant point of the mains; we excite the field magnet or magnets F, Figure 1,
partly by any of the usual known or other suitable means, such as from any separate
source, (as shewn at B, for example) or by means of a current obtained from the
armature conductor or from a special coil on the same, in either of the latter cases, it
being provided with a commutator for the purpose or by the commutated secondary
current of a transformer, the primary of whichi is a shunt on the terminals or mains,
the source of this partial excitation being connected to the field at a, a. Across some
portion of one of the main conductors M M or resistance placed in the main circuit
(as at R) we take a shunt or derivation, the current in which derivation is commu-
tated by means of a commutator C, and brushes in the manner usual in correcting
or commutating alternate currents, and conducted to a separate coil b b on the
field F or with the initial exciting circuit already referred to. The shunted and
commutated current so obtained is for the purpose of obtaining constant potential

page_text: employed to strengthen the fields F, and as this derived current is proportionate to
the main current, we are by suitable proportioning of the machines enabled to
maintain a constant or such a rising or falling difference of potential as is required.
For constant current working, this shunted and commutated current is made to
exercise a de-magnetising effect.
Although in figure 1 and in succeeding figures we have shewn the excitation of the
field as being the effect of currents flowing in two separate coils or windings a a
and we do not limit ourselves to this arrangement as we may employ one coil and
connect the two sources of current to the saine in the manner necessary to obtain
strengthening of the magnet F by the current shunted from the resistance R in the
case of constant potential working and weakening of the magnet F by the current
shunted from the resistance R, when our object is to maintain constant the current in
the mains. Thus Figure 2 shews an arrangement by which only one winding a a on
the fields F is required, B indicating any separate source of excitation connected in
series with the auxiliary source from the resistanco R.
We may also use the method shewn in Figure 2 where the armature A¹ of the
alternate current generator is provided with two separate and distinct coils or sets of
coils or windings, the main winding m, m, providing the main current as in Figure
there being a second and much smaller winding n n which is used for the purpose of
supplying the initial excitation of the field F. This winding n n is connected to the
exciting coils or winding on F its current being commutated by the commutator C
A portion of this Circuit consists of the resistance R placed in one of the main
Conductors In this way a portion of the main current is shunted from the resistance R
and is used in combination with the current produced by the armature winding n n
for the purpose of exciting and regulating the field F. This principle of taking a
Shunt from a portion of the main for the purpose of supplying suitable correction is
applicable to continuous current generators and we employ it for the purpose of
adapting compound dynamos to meet the requirements of different circuits.
[
"
Hitherto it has been necessary to specially wind the field magnets of each compound
dynamo machine for the particular circuit or circuits it has to supply so as to obtain
such રી characteristic as will allow for the loss of potential in the Conductors. In
making machines on a manufacturing scale this is an inconvenience and a source of
expense, to avoid which is one of the objects of this invention.
Figure 3 shews the arrangement wo adopt for this purpose where C is the commu-
tator or Collector and F the field magnet or magnets of a continuous current generator
of which a a is the shunt or initial excitation circuit which may be connected to the
brushes direct as shewn in this Figure or across the armature, and the series winding
conjointly is the series or correcting coil connected to the terminals of the
resistance R placed in one of the mains M M' and so wound as to enable it to
exercise the maximum correction which would be required on a circuit of con-
siderable length or resistance in which case the resistance of R is infinite. When
the circuit to be supplied is of less than the maximum resistance we place in the
main circuit a permanent resistance, the amount of which depends upon the corrective
effect required of the coil b b. In this way we avoid the expense of specially winding
or compounding each dynamo for its particular circuit. We also employ this method
for the simplification of manufacture in the case of dynamo machines driven at
irregular speeds.
A dynamo machine driven by a separate engine usually runs considerably faster
when the load is small than when the full load is on. We therefore also use this
arrangement shown in figure 3 to adapt a compound dynamo to the conditions as
regards percentage of variation of speed under which it has to work, instead of
as hitherto being obliged to wind it specially to compensate for such variation. In
the case of the use of dynamo machines as electric motors we may make use of the
improved arrangement shewn in Figure 3 (with the exception that the series coil in
such case is arranged to produce a partially demagnetising effect) for the purpose of
adjusting any motor so constructed to maintain constant speed in a parallel dis-
tribution system.

page_text: Thus we are enabled to use machines of similar construction and winding under
circumstances where different percentages of loss of potential in the main conductors
or in the branch conductors supplying the motors, when the current undergoes
variation would otherwise necessitate special winding of the field magnets for
each case.
When a separate exciter is employed for the fields of either continuous or alterating
current machines we apply this Invention to obtain self regulation of the main
generator in the following improved way. The current shunted and (in the case of
alternating current dynamos) commutated from a portion of one of the main con-
ductors or a resistance placed in the mains as described with reference to Figures 1
and 2, is passed through the field coils or through a separate coil or circuit of the
fields of the exciter. In this case the initial excitation of the main dynamo may be
obtained from the separate exciter, the correcting excitation being produced simply
by augmentation of the field current of the exciter in the manner indicated.
In
Figures 4 and 5 illustrate this application of our invention. Figure 4 illustrating
a continuous current machine and Figure 5 an alternate current machine.
Figure 4, is the commutator or collector and F the field magnet or magnets of
a continuous current dynamo supplying the mains M. M' in one of which wo
usually place a resistance R. The fields F are excited by a current generated by
a separate dynamo of which is the commutator or collector and the field
magnet or magnets. This separate exciter may be either a shunt, compound, or
series wound machine. In Figure 4 it is shewn as a shunt machine so far as its
Its brushes are connected
own current is concerned a¹ a being the shunt circuit.
directly to the terminals a a of the exciting coil of the field F. In addition to tho
shunt coil a a¹ the field is provided with a coil or winding b b which is connected
directly to the terminals of the resistance R or across a portion of one of the main
conductors M M³ corresponding to tho resistance R. Thus the coil bb forms a
portion of the main circuit supplied by the machine of which is the commutator
and thus by an exceedingly small expenditure of energy the field
exciter is controlled by the current flowing through the mains M M
larger field F and the main current or electro motive force, is
augmentation or diminution of the exciting current in the coil a a.
In the constant electro-motive force systems the current in the coil or winding bb
is made to assist or strengthen the magnetization of the field f. In the case of
working with constant current the coil b b opposes or weakens the effect produced by
the coil a' a¹.
of the separate
and in turn the
regulated by an
When the current which is, or may be required to be, provided by the main
dynamo machine is not very large, wo dispense with the resistance R, and place the
coil directly in the external circuit of the main dynamo machine. For the
following reasons however we prefer in most instances to retain the resistance R.
Firstly because by our improved method of regulation we require only a very small
magnetising effect on the fields in order to obtain even a considerable regulating
effect on the large field or fields F, and this effect on fis not or may not be con-
veniently obtained by the use of the whole of the current supplied by the main
dynamo and Secondly because by the use of the resistance R (which may be so small
that the loss in it may be ignored) we are enabled readily to secure the amount of
regulation or correction which the circumstances of the case may require either as
regards electro-motive force, current, or speed as already explained with reference to
the preceeding figures.
In applying this improvement to separate exciters which are series or compound
wound, the main current or the portion of the main current shunted from the
resistance R may pass through a separate coil or winding on the field f, as at b b
Figure 4 or it may be connected to a part or the whole, of the ordinary winding as
may be readily understood.
This improved method of obtaining self-regulation of a separately excited dynamo
machine is applied by us to alternate current machines by using a somewhat similar
arrangement to that described with reference to Figure 4.but with the addition of a

page_text: commutator, as shewn in Figure 5 where F is the field magnet or magnets, A¹ the
armature and A the collector of an alternate current machine of which M M are the
main external conductors in one of which a resistance R is placed. The field F which
is wound with a coil or coils a a is magnetised by a separate exciter of which is the
field magnet or magnets having a shunt (or it may be a series or compound)
winding a' a' and a regulating coil b b.
From the terminals of the resistance R a shunt is taken, the current so obtained
being commutated, or made continuous in direction, by the commutator C placed
on the shaft of the main machine F A' A Brushes rest on C from which the
commutated current is conducted to the winding bb. Or instead of obtaining the
current for the correcting coil b b on the field of the separate exciter by shunting it
from a portion of the mains as in Figure 5 we may make use of the modification
shewn in Figure 6. A transformer of which the primary p is in the main circuit has
its secondary s connected with a commutator C placed on the shaft of the machine
the curront from s being thereby commutated through bb.
Or we may employ the modification shewn in Figure 7 according to which the
initial excitation of the alternate current generator is obtained from the separate
exciter the initial field a¹ a¹ of which is supplied by way of the commutator C
from the secondary circuit s of a transformer the primary p of which transformer is a
shunt on the mains or terminals M M'. The alternate current machine is shewn as
before, F indicating the field, A¹ the armature and A the collector and M M' are the
mains in one of which is placed a resistance R. The separate exciter by its com-
mutator or collector C and brushes is connected directly to the coil or winding a a
on the field magnet or magnets F.
The correcting or regulating coil b b of the separate exciter is supplied by current
from the main by the commutator C.
In the arrangement shown in Figure 8 the whole excitation of the field F is as
before derived from the separate exciter the fields of which are magnetised by the
commutated current from two transformers one in parallel and the other in series
with the mains, or' preferably from the secondary s of a transformer the primary pp'
of this transformer being composed partly of a shunt (p) on the mains or terminals
and partly of a conductor (p) placed in the main circuit. Or the fields of the
exciter may be magnetised as shewn in Figure 9 directly from the alternate current
generator FA¹ A the excitation of the field ƒ being obtained partly by a shunt from
the mains or terminals by way of the commutator C and partly by a shunt by
way of the commutator C from a portion of the mains M M or from a resistance Ŕ
placed in the mains in the manner herein before described.
In using the current shunted from the ends of the resistance in the main the
commutator is arranged as in ordinary commutation of alternate currents and is not
a collector to merely direct into the magnetising circuit the alternate pulsations of
currents which are already of one direction.
Instead of shunting a fraction of the main current from a portion of the main
conductor, or from a resistance placed in the main conductor for the purpose
indicated, we may commutate the whole current but prefer for the reasons herein-
before given only to take a portion of it, shunted from the main conductor in the
manner described.
Having now particularly described and ascertained the nature of our said Inven-
tion and in what manner the same is to be performed we declare that what we
claim is.
First In dynamos the method of regulation or compounding by means of
(1) Current shunted from a portion of one of the mains or
(II) Current obtained from the secondary circuit of a transformer the primary
of which is in connection with the mains (a commutator being used in the
case of alternate current machines) the regulating current so obtained being
made to control the magnetic field directly, as described or to control it
indirectly by acting on the magnetic field of a separate exciter.

page_text: Second In an alternate current electric generator the use of a portion of the
main current shunted from one of the main conductors, commutated and passed
through a field winding on the field magnet or magnets in combination with a con-
stant or approximately constant initial excitation of the fields for the purpose of
obtaining self regulation of the current or potential difference substantially as
hereinbefore described with reference to Figures 1 and 2 of the accompanying
diagrams.
Third In a continuous current compound dynamo or electric generator correcting
winding placed in parallel connection with a portion of one of the mains or in
parallel with a resistance placed in one of the mains for the purpose of adapting the
said dynamo to suit the conditions of the circuit on which it has to run or to com-
pensate for the speed variation of the engine driving it or both substantially as
described with reference to Figure 4.
Fourth For the purpose of regulating an alternate current electric generator the
arrangement illustrated by Figure 2^ consisting of a separato armature winding in
combination with a shunt current from a portion of one of the mains the two currents
acting jointly on a single field winding substantially as hereinbefore described.
Fifth In a continuous current compound dynamo used as a motor a correcting
winding placed in parallel connection with a portion of one of the mains or in parallel
with a resistance placed in the main circuit or branch of the main circuit supplying
the said motor for the purpose of adapting the said motor to run at a constant speed
under different circumstances as regards the loss of potential in the said main or
branch circuit or variation of load substantially as described with reference to
Figure 3 of the accompanying diagrams.
Sixth On the field magnet or magnets of the exciter of a continuous current
dynamo electric machine a coil or winding placed in series connection with one of
the main conductors or in parallel connection with a portion of one of the main
conductors or in parallel connection with a resistance placed in one of the main con-
ductors for the purpose of obtaining self regulation of the current or electro motive
force in the mains for the purpose of adapting the dynamo machine or machines to
the requirements of the circuit or to compensate for variation of the speed of rotation
or for both of theso purposes substantially as described with reference to Figure 4 of
the accompanying diagrams.
Seventh On the field magnet or magnets of the oxcitor of an alternate current
dynamo electric machine a coil or winding placed in series connection with one of
the main conductors or in parallel connection with a portion of one of the main
conductors or in parallel connection with a resistance placed in one of the main
conductors and provided with a commutator for the purpose of obtaining self
regulation of the current or electro motive force in the mains for the purpose of
adapting the dynamo machine or machines to the requirements of the circuit or to
compensate for variation of the speed of rotation or for all these purposes sub-
stantially as described with reference to Figure 5 of the accompanying diagrams.
Eighth The self regulation of an alternate current dynamo electric generator by
controlling the fields of the separate exciter by means of the main current acting
through the medium of a transformer the primary of which is in the main circuit, the
secondary current of the transformer commutated, supplying the correcting
excitation of the separate exciter substantially as describod with reference to Figure 6
of the accompanying diagrams.
Ninth The self regulation of an alternate current dynamo by controlling the field
of the separate exciter by current shunted from a resistance placed in the main the
initial excitation of the said exciter being effected by the secondary current of a
transformer the primary of which is a shunt on the mains substantially as described
with reference to Figuro 7 of the accompanying diagrams.
Tenth For the purpose of obtaining self regulation in an alternate current dynamo
electric machine the arrangement substantially as described with reference to
Figure 8 consisting of two transformers or of a transformer having two primary
circuits one arranged as a shunt on the mains the other being placed in the main

page_text: circuit and a secondary circuit with a commutator used to excite the field magnet
or magnets of the separate exciting dynamo substantially as described with reference
to Figure 8 of the accompanying diagrams.
Eleventh For the purpose of obtaining self regulation in an alternate current
dynamo electric machine the arrangement substantially as described with reference
to Figure 9 of the accompanying diagrams the said arrangement consisting of a
commutated current obtained as a shunt from the terminals and producing the initial
excitation of the separate exciter and a commutated current obtained as a shunt, from
a portion of one of the mains and providing the correcting excitation of the separato
excitor.