A Method of Compensating Variations of Load at Electrical Stations.
Year: 1893

page_text: Date of Application, 24th Aug., 1893
Complete Specification Left, 4th May, 1894-Accepted, 16th June, 1894
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Messrs. SIEMENS & HALSKE, of Berlin, in the
German Empire, Electrical Engineers.]
A Method of Compensating Variations of Load at Electrical
Stations.
We, SIEMENS BROTHERS & Co. Limited of 12 Queen Anne's Gate,
Westminster, in the County of Middlesex, Electrical Engineers, do hereby declare
the nature of this invention to be as follows:-
This invention relates to means of practically compensating, especially in the
working of railways or tramways by electricity, the variations of the load on the
current generator caused by the irregularities of the service; the invention can
however be applied generally to continuous current distributing systems, where the
working current is liable to considerable fluctuations.
For this purpose, an accumulator battery is connected in parallel with the
current generator, and in this branch circuit is introduced an auxiliary generator
which is excited in such a way, that, when there is an increase in the working
current, it raises the total E.M.F. in the accumulator branch circuit, and when
there is a decrease, it immediately lowers it, the fluctuations of the working
current being thus entirely or almost entirely taken up by the accumulators. If, as
has been already done in the case of electric light installations, an accumulator
battery alone without any auxiliary dynamo is connected parallel to the generators,
it can only take up a part of the fluctuation of the working current, so that in
this way generators cannot be protected from the sudden successive fluctuations
of load.
The auxiliary dynamo inserted in the branch circuit of the accumulators may
be driven in any convenient way, such as au electromotor connected to the supply
mains. The exciting of this dynamo as mentioned above is effected in the following
manner.
Its field magnets have two windings, the one traversed by the working current
which is liable to considerable fluctuations, the other preferably connected direct
to the accumulators. The two windings are in action opposed to each other.
The E.M.F. which the winding traversed by the working current tends to create,
reinforces the E.M.F. of the accumulators, but the E.M.F. produced by the other
winding opposes the E.M.F. of the accumulators. The number of turns in both
windings is so calculated that, with normal strength of working current, the
two windings balance each other, consequently the E.M.F. of the auxiliary
dynamo is then nil. The accumulator battery then neither gives current to the
distributing network nor receives current from it. As soon however as the
working current increases above the normal value, the total E.M.F. is increased in
the branch circuit of the accumulators, which then supply current to the network.
If now the number of turns of the windings traversed by the working current be
correctly chosen, it is possible to arrange that on every rise of the working current
above the normal value, the E.M.F. in the accumulator circuit shall be so much
increased that the accumulators give to the network just as much current as the
sudden increased consumption requires; on the contrary. if the strength of the
working current falls below the normal value, the action of the second winding
which is connected to the accumulators is the greater, and the auxiliary dynamo

page_text: has then an E.M.F. opposed to that of the accumulators, which reinforces the
E.M.F. of the generator and thus a charging current is sent through the
accumulators. The excess of current which is not required for the network is
therefore taken up by the accumulators. In this way all the fluctuations of
current in the network are compensated by means of the accumulators, which are
alternately charged and discharged, the generator being thus protected from the
fluctuations.
This regulation can be carried out with considerable exactness so that even
large fluctuations in the working current occasion only small variations in the
current and potential difference of the generators. It is thus possible to employ
the same generators, to supply current for electric railways, and at the same time
for electric lighting; and thus, by combining together electric light and power
stations, great commercial advantage may be obtained.
The second exciting winding of the auxiliary machine, as already mentioned,
is connected in parallel with the accumulators. By this a further result is attained.
As is well known, the current traversing the accumulators is in great measure
dependent on their counter E.M.F. This influence of the counter E.M.F. of the
accumulators is equalized in the present case to a certain degree, by the second
exciting winding which depends on the potential difference of the accumulators,
compensating the increase or decrease of the E.M.F. of the accumulators by its
influence on the E.M.F. of the auxiliary dynamo. For example, if the
accumulators have suddenly to discharge, giving current to the network, their
E.M.F. falls, and simultaneously their potential difference, and consequently the
current in the second exciting winding. It will follow that the E.M.F. of the
auxiliary dynamo will rise in the sense of the E.M.F. of the accumulators, so
that the fall of the E.M.F. of the accumulators is not followed by a fall in the
total E.M. F. in the circuit of the accumulators and of the auxiliary dynamo,
and consequently is not followed by any fall in the discharge current of the
accumulators.
The result is similar with an increase in the E.M.F. of the accumulators, if
they are traversed by a current in the charging direction. Then by means of the
second exciting winding the E.M.F. of the auxiliary dynamo acting on the
accumulators is raised, therefore the charging current, which would otherwise
have decreased owing to the increase in the counter E.M.F. of the accumulators,
is kept nearly constant.
A resistance is further inserted in the circuit of the second exciting winding, by
means of which the current in this winding can be adjusted at will so that the
auxiliary machine, if the existing driving arrangements permit, can also be used as
an ordinary auxiliary machine, that is for charging or discharging the accumulators
inserted in its circuit.
The strength of the charging or discharging current for which the regulating
resistance has been adjusted fluctuates slowly, because the auxiliary machine, as
remarked previously, compensates simultaneously all fluctuations of the current
in the network by corresponding variations of the current traversing the
accumulators. This regulation by means of a regulating resistance is obviously
not novèl.
The second exciting winding might be connected directly to the network. The
main object of the present invention is the regulation of the E.M.F. of the auxiliary
dynamo by the main current itself.
Dated this 24th day of August 1893.
ABEL & IMRAY,
Agents for the Applicants.

page_text: A Method of Compensating Variations of Load at Electrical
Stations.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate,
Westminster in the County of Middlesex, Electrical Engineers, 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 relates to means of practically compensating, especially in the
working of railways or tramways by electricity, the variations of the load on the
current generator caused by the irregularities of the service; the invention can
however be applied generally to continuous current distributing systems, where
the working current is liable to considerable fluctuations.
For this purpose, an accumulator battery is connected in parallel with the
current generator, and in this branch circuit is introduced an auxiliary generator
which is excited in such a way that, when there is an increase in the working
current, it raises the total E.M.F. in the accumulator branch circuit and when
there is a decrease it immediately lowers it, the fluctuations of the working current
being thus entirely or almost entirely taken up by the accumulators.
If, as has been already done in the case of electric light installations, an
accumulator battery alone without any auxiliary dynamo is connected parallel to
the generators, it can only take up a part of the fluctuations of the working
current, so that in this way generators cannot be protected from the sudden
successive fluctuations of load.
The auxiliary dynamo inserted in the branch circuit of the accumulators may
be driven in any convenient way, such as an electromotor connected to the supply
mains. The exciting of this dynamo as mentioned above is effected in the
following manner.
Its field magnets have two windings, the one traversed by the working current
which is liable to considerable fluctuations, the other preferably connected direct
to the accumulators.
The two windings are in action opposed to each other. The E.M.F. which the
winding traversed by the working current tends to create, reinforces the E.M.F. of
the accumulators, but the E.M.F. produced by the other winding opposes the
E.M.F. of the accumulators. The number of turns in both windings is so
calculated that, with normal strength of working current, the two windings
balance each other, consequently the E.M.F. of the auxiliary dynamo is then nil.
The accumulator battery then neither gives current to the distributing network
nor receives current from it. As soon however as the working current increases
above the normal value, the total E.M.F. is increased in the branch circuit of the
accumulators, which then supply current to the network.
If now the number of turns of the windings traversed by the working current
be correctly chosen, it is possible to arrange that on every rise of the working
current above the normal value, the E.M.F. in the accumulator circuit shall be so
much increased that the accumulators give to the network just as much current as
the sudden increased consumption amounts to; on the contrary, if the strength of
the working current falls below the normal value, the action of the second winding
which is connected to the accumulators is the greater, and the auxiliary dynamo
has then an E.M.F. opposed to that of the accumulators, which reinforces
the E.M.F. of the generator and thus a charging current is sent through the
accumulators.
The excess of current which is not required for the network is therefore taken
up by the accumulators.

page_text: In this way all the fluctuations of current in the network are compensated by
means of the accumulators, which are alternately charged and discharged, the
generator being thus protected from the fluctuations.
This regulation can be carried out with considerable exactness so that even large
fluctuations in the working current occasion only small variations in the current
and potential difference of the generators.
It is thus possible to employ the same generator, to supply current for electric
railways, and at the same time for electric lighting; and thus, by combining
together electric light and power stations, great commercial advantage may be
obtained. It is then obviously unnecessary to use the conductors in which the
current fluctuates for exciting the auxiliary dynamo in the accumulator branch
circuit.
The second exciting winding of the auxiliary machine, as already mentioned, is
connected in parallel with the accumulators.
By this a further result is attained. As is well known, the current traversing
the accumulators is in great measure dependent on their counter E.M.F.
This influence of the counter E.M.F. of the accumulators is equalized in the
present case to a certain degree, by the second exciting winding which depends on
the potential difference of the accumulators, compensating the increase or decrease
of the E. M.F. of the accumulators by its influence on the E.M.F. of the auxiliary
dynamo. For example, if the accumulators have suddenly to discharge, giving
current to the network, their E.M.F. falls, and simultaneously their potential
difference, and consequently the current in the second exciting winding. It will
follow that the E.M.F. of the auxiliary dynamo will rise in the sense of the E.M.F.
of the accumulators, so that the fall of the E.M.F. of the accumulators is not
followed by a fall in the total E.M.F. in the circuit of the accumulators and of the
auxiliary dynamo, and consequently is not followed by any fall in the discharge
current of the accumulators.
The result is similar with an increase in the E.M.F. of the accumulators, if they
are traversed by a current in the charging direction. Then by means of the second
exciting winding the E.M.F. of the auxiliary dynamo acting on the accumulators is
raised, therefore the charging current, which would otherwise have decreased
owing to the increase in the counter E.M.F. of the accumulators, is kept nearly
constant.
A resistance is further inserted in the circuit of the second exciting winding,
by means of which the current in this winding can be adjusted at will so that the
auxiliary machine, if the existing driving arrangements permit, can also be used as
an ordinary auxiliary machine, that is for charging or discharging the accumulators
inserted in its circuit.
The strength of the charging or discharging current for which the regulating
resistance has been adjusted fluctuates slowly, because the auxiliary machine, as
remarked previously, compensates simultaneously all fluctuations of the current in
the network by corresponding variations of the currrent traversing the accumu-
lators. This regulation by means of a regulating resistance is obviously not
novel. The second exciting winding might be connected directly to the network.
The main object of the present invention is the regulation of the E.M.F. of the
auxiliary dynamo by the main current itself.
The accompanying drawing shews a diagram of the above described arrangement.
L' and L are the conductors leading from the main current generator B to the
electric railway CC, in which consequently the working current is subject to
considerable fluctuations, while the current of the generator B is to be maintained
constant in spite of such fluctuations, Z is the auxiliary dynamo driven by a belt T
or otherwise from any suitable motor and having two exciting windings E' and E
of which E' is included in the circuit L' L2, while E2 is included in the branch
circuit of the accumulators A connected in parallel with the current generator B.
L'L' are branch conductors for supplying lamps from the generator; R is the
regulating resistance, also included in the circuit of the accumulators and

page_text: winding E. The action of this arrangement will be readily understood from what
has been described above.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
A method of compensating for variations of load in a continuous current
distributing system wherein an accumulator battery is connected in parallel with.
the current generator, in the circuit of which is placed an auxiliary current
generator having an exciting winding supplied from the main circuit and a second
exciting winding supplied from the accumulator battery, the two exciting currents
being so arranged as to oppose each other's action, so that when there is an
increase in the load the auxiliary generator raises the total E.M.F. in the
accumulator circuit, while when there is a decrease it lowers the same, thus causing
in the first case current to be supplied from the accumulators to the network and in
the second case, current to be supplied from the generator to the accumulators,
substantially as described.
Dated this 4th day of May 1894.
ABEL & IMRAY,
Agents for the Applicants.