Electric Machines with a Main Circuit and Apparatus therefor.
Year: 1886

page_text: Date of Application, 30th Oct., 1886.
Complete Left, 5th July, 1887.
Complete Accepted, 26th Aug., 1887.
[Communicated from abroad by The Firm of SIEMENS & HALSKE, of 94, Markgrafen
Strasse, Berlin, in the Empire of Germany, Electrical Engineers.]
Electric Machines with a Main Circuit and Apparatus therefor.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery Lane, in
the County of Middlesex Consulting Engineer and Patent Agent, do hereby declare
the nature of this invention to be as follows
:―
If two or more alternate current dynamo machines are required to send into one
common outer circuit a steady current equal to the sum of the currents which each
each machine would deliver singly into the same circuit, the following conditions
must be complied with: Firstly, the difference of potential at the terminals must
be of the same value in all machines connected in parallel arc, and secondly,
the current impulses must coincide with each other in all machines connected in
parallel arc.
The equalisation of the difference of potential at the terminals can be effected by
known methods so that the first question presents no serious difficulty, but the second
condition is not so easy of solution. Experiments have proved that the currents of
two or more alternate current machines when first connected in parallel arc, do, as a
rule, not coincide, even when the machines are of precisely the same construction and
are driven from one and the same shaft.
After a certain lapse of time no doubt coincidence occurs, namely, so long as
the current impulses of two machines do not coincide, the machines receive impulses
from each other, which are added to the self generated impulses in the case of oppo-
site phases, or are subtracted therefrom in the case of phases of the same direction.
In the first case both machines are subject to retardation, in the second case, on the
other hand, the first machine is retarded and the second accelerated, so that the
phases tend to coincide. The same thing then again occurs but in the opposite
sense, as the first machine will then be accelerated and the second one retarded, so
that the phases will recede from each other. As however the extent of the first

page_text: named approach of the phases exceeds that of the recession, it follows that by a
continuance of these fluctuations there will be a gradually increased approach of the
phases until at last they coincide.
During this period any lamps or motors connected to the outer circuit would work
very irregularly; it is therefore not practically feasible to work alternate current
machines in parallel circuit by coupling them, one after the other, to the outer circuit.
even if the polar tension is of the same value in all such machines.
The present invention has for its object to avoid this difficulty and consists in the
employment of means whereby the alternate current machines that are to be coupled
to a circuit already charged by one or more other such machines, are automatically
coupled at the moment when the impulses coincide. For this purpose, assuming that
one alternate current machine is connected to and charging the outer circuit, and
that a second one is to be coupled up when its impulses coincide with the first, a
horse shoe electro magnet is employed, the coil on one limb of which has its two ends
connected respectively to the two leads of the outer circuit, while the coil on the
other limb has its one end connected to the one lead of the outer circuit and its other
end connected to the one terminal of the second machine, whose other terminal is
connected to the same lead of the outer circuit as that to which the one end of the
last named coil is connected, so that the coil of the second limb is practically connected
with both its ends to the two terminals of the second machine. The electro magnet
has an armature held away therefrom by a spring or weight, which armature is
electrically connected with that terminal of the second machine which is directly
connected to the coil on the second limb of the magnet, while on the attraction of the
armature by the electro magnet, it is caused to make a contact whereby the said
terminal of the second machine is electrically connected to the second lead of the outer
circuit, thus including the second machine in the circuit. Before this takes place,
the coil on the first named limb of the electromagnet has a current passing through it
which is derived from that of the first machine and proportionate to the difference
of potential between the two leads of the outer circuit, while the current passing
through the coil of the second limb is proportionate to the difference of potential
between the two terminals of the second machine. So long as the current impulses
of the two machines do not coincide, the magnetic effects of the two limbs of the
magnet will to a certain extent be opposed to, and consequently weaken, each other.
But as soon as the impulses of the second machine coincide with those of the first,
the currents passing through the two coils of the electro magnet will become such as
to increase the power of the magnet sufficiently to overcome the resistance of the
spring or weight holding back the armature, so that this in being attracted will effect
the coupling up of the second machine as described. The two coils of the electro-
magnet will be thereby also coupled up and the armature will remain permanently
attracted.
In a similar manner one and the same electro-magnetic apparatus may be made.to
automatically couple two or more alternate current machines to the outer circuit when
their impulses coincide, or there may be a separate apparatus provided for each
machine which is to be coupled up. In the place of the electromagnet with two
limbs, one with a single limb may be employed having two coils connected as before
described; also in place of an electro-magnet and armature there may be employed a
solenoid with two coils and a movable iron core, or two solenoids without cores may
be used, so arranged that on the coincidence of the impulses occurring a mutual
attraction or repulsion takes place sufficient to overcome the resistance of a spring or
weighted contact.
ABEL & IMRAY,
28, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: Improvements in Coupling Two or More Alternate Current Dynamo
Electric Machines with a Main Circuit and Apparatus therefor.
I, CHARLES DENTON ABEL of No. 28 Southampton Buildings Chancery Lane in
the County of Middlesex. Consulting Engineer and Patent Agent 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:-
If two or more alternate current dynamo machines are required to send into one
common outer circuit a steady current equal to the sum of the currents which each
machine would deliver singly into the same circuit, the following conditions must be
complied with: Firstly the difference of potential at the terminals must be of the
same value in all machines connected in parallel arc, and, Secondly, the current
impulses must coincide with each other in all machines connected in parallel arc.
The equalisation of the difference of potential at the terminals can be effected by
known methods so that the first question presents no serious difficulty but the second
condition is not so easy of solution. Experiments have proved that the currents of two
or more alternate current machines when first connected in parallel arc, do, as a rule
not coincide even when the machines are of precisely the same construction and
are driven from one and the same shaft.
After a certain lapse of time no doubt coincidence occurs. Namely so long as the
current impulses of two machines do not coincide the machines receive impulses from
each other which are added to the self generated impulses in the case of opposite
phases, or are subtracted therefrom in the case of phases of the same direction. In
the first case both machines are subject to retardation, in the second case on the other
hand the first machine is retarded and the second accelerated, so that the phases tend
to coincide.
The same thing then again occurs but in the opposite sense, as the first machine will
then be accelerated and the second one retarded, so that the phases will recede from
each other. As however the extent of the first named approach of the phases exceeds
that of the recession it follows that by a continuance of these fluctuations there will
be a gradually increased approach of the phases until at last they coincide.
During this period any lamps or motors connected to the outer circuit would work
very irregularly; it is therefore not practically feasible to work alternate current
machines in parallel circuit by coupling them, one after the other, to the outer circuit
even if the polar tension is of the same value in all such machines.
The present invention has for its object to avoid this difficulty and consists in the
employment of means whereby the alternate current machines that are to be coupled
to a circuit already charged by one or more other such machines are automatically

page_text: coupled at the moment when the impulses coincide. For this purpose assuming that
one alternate current machine is connected to and charging the outer circuit, and that
a second one is to be coupled up when its impulses coincide with the first, a horse
shoe electro magnet is employed the coil on one limb of which has its two ends
connected respectively to the two leads of the outer circuit, while the coil on the
other limb has its one end connected to the one lead of the outer circuit and its other
end connected to the one terminal of the second machine, whose other terminal is
connected to the same lead of the outer circuit as that to which the one end of the
last named coil is connected, so that the coil of the second limb is practically connected
with both ends to the two terminals of the second machine.
The electromagnet has an armature held away therefrom by a spring or weight,
which armature is electrically connected with that terminal of the second machine
which is directly connected to the coil on the second limb of the magnet, while on the
attraction of the armature by the electro-magnet it is caused to make a contact whereby
the said terminal of the second machine is electrically connected to the second lead of
the outer circuit thus including the second machine in the circuit.
The accompanying drawing shews diagrammatically the arrangement of this electro-
magnet in connection with an alternate current machine M' which is permanently
connected to the leads L' L' of the outer circuit W and a second alternate current
machine M2 arranged in parallel arc to M¹ which is to be coupled up with the
leads LI. E is the electro-magnet the two ends of the coil of whose limb s¹ are
connected respectively to the leads L' and L2 while the ends of the coil of limb,2
are connected respectively to the lead L' and to the lead a² or in other words they are
connected to the two terminals of the machine M², as L¹ is connected to the one
terminal thereof and the lead a² is connected to the other terminal.
The coil of therefore has a current passing through it, which is supplied by the
machine M² and which is proportional to the difference of potential between the leads L¹
and L2; the current passing through the coil of on the other hand is proportional
to the difference of potential between the terminals of the machine M².
So long as the current impulses of the two machines do not coincide, the magnetic
forces of the two limbs 2 act to a certain extent in opposite directions and conse-
quently weaken each other so as not to be capable of attracting the armature A. But
as soon as, by the influence of the machine M¹ upon the machine M² a coincidence of
impulses is brought about, the magnetic force of the electro-magnet will be equal to
the sum of the magnetic forces produced in s¹ and 2 when it will be sufficient to
attract the armature A against the opposed action of the spring F. The armature
will then make contact at n with the connection of coil s¹ through b² with the main
lead L2 and as the armature is also connected with the terminal a² of the machine M²
it follows that this terminal will now be coupled up with the main lead L². As both
coils of the electro-magnet are now connected with the leads L' and L² the armature
will remain permanently attracted by the electro-magnet.
In the same way and with the same apparatus any number of alternate current
machines can be coupled up consecutively in parallel are. For example in order to
couple up the third machine M³ parallel to M and M² a² and 62 are connected directly
with each other, and the ma² and n 2 are separated and m is connected with a³
and n with 63. The automatic coupling up of the machine M³ is then effected in the
same manner as above described with reference to M². Or instead of effecting the
coupling up of several machines consecutively by means of one and the same
apparatus, they may all be coupled up simultaneously by means of separate apparatus
to each machine.
In the place of the electro-magnet with two limbs, one with a single limb or core
having two coils connected as above described may be employed; also instead of
using an electro-magnet with polarised or non polarised armature, a solenoid formed
of two insulated coils, with iron core, may be employed or lastly there may be used
two solenoids with or without cores so arranged relatively to each other that on the
coincidence of the impulses occurring a mutual attraction or repulsion takes place
sufficient to overcome the opposing force of a spring or weighted contact piece.

page_text: Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is :-
The method of coupling two or more alternate current machines in parallel arc with
a main circuit, wherein leads of the main circuit or the terminals of the alternate
current machine permanently connected therewith are connected to the one coil of an
electro-magnet or solenoid, the second coil of which is connected to the terminals of
the alternate current machine to be coupled up, the electro-magnet or solenoid being
so arranged that it will effect the automatic coupling up of the last named machine on
the occurrence of the coincidence of its current impulses with those of the other
machine, substantially as herein described.
ABEL & IMRAY,
Agents for the Applicant.