Method and Apparatus for Effecting the Connection in Parallel of Alternate Current and Polyphase Dynamos and Motors.
Year: 1896

page_text: Date of Application, 6th Feb., 1895
Complete Specification Left, 25th Oct., 1896-Accepted, 6th Feb., 1897
mmunicated from abroad by SIEMENS AND
HALSKE, Or berna, in the rerman
Empire, Electrical Engineers.]
Method and Apparatus for Effecting the Connection in Parallel of
Alternate Current and Polyphase Dynamos and Motors.
We, SIEMENS BROS. & 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:-
As is well known, alternate current dynamos or rotary current dynamos before
being connected in parallel to the supply circuit, must be brought into
synchronism.
.
In order to ascertain such synchronism, glow lamps are usually employed..
connected between the corresponding terminals of the machines; the extinguishing
of such lamps then affords the indication of the correct time for connecting in
parallel. This arrangement is subject to the disadvantage that it does not
indicate whether the machine to be connected in parallel, is running too fast or too
slow, as in both cases the same indication is given, namely a fluctuation in the light.
of the glow lamps.
This materially complicates the connecting in parallel as it cannot be ascertained
in what direction the speed has to be adjusted.
The present invention relates to means whereby it can be readily ascertained
with respect to two machines that require to have synchronous motion, firstly, which
of the machines is running too fast or too slow, and secondly, when synchronism
has been attained.
We will describe the said invention with reference to the accompanying
diagrammatic drawings, in which
Fig. 1 shews the mode of connection heretofore employed for example for a
rotary current dynamo, A' B' C¹ and A B C are the terminals of the machines
to be connected in parallel. The glow lamps, indicated by crosses, are connected
between the corresponding terminals namely between A' and A³, B¹ and B³,
Cand C.
The machines can be connected in parallel by closing the three-pole switch D
when the potentials at the said corresponding terminals are equal. The proper
moment for doing this is ascertained when the glow lamps are extinguished.
Fig. 2 shews an essentially different mode of connection according to the
present invention, the glow lamps not being connected to corresponding terminals
of the rotary current machines.
The one lamp is connected between A' and A³, but the second is connected
between B and C, and the third between C and B. With this arrangement in
consequence of the interference of the impulses of electromotive force, the lamps

page_text: do not glow simultaneously but consecutively, with an asynchronous motion of the
machines. The order of sequence of such incandescence depends upon whether
the machine to be connected in parallel lags behind or is ahead of synchronism.
Consequently the said order of sequence affords a test for ascertaining which
machine runs faster or slower and a single trial will enable the operator to
determine whether the machine to be connected in parallel runs too fast or
too slow.
With the arrangement at Fig. 2 the one lamp being connected between corre-
sponding terminals A1 and A2 of the machines, the switch D can be closed at the
moment when the potentials of A1 and A2, B1 and B', C' and C coincide as to
phase and amplitude. The potential difference between A¹ and A' is then equal
to zero, and the corresponding lamp is extinguished while the other two glow with
about one half the normal brightness; consequently the extinguishing of the lamp
between A¹ and A' indicates the proper moment for connecting in parallel. In
order to indicate this moment still more accurately a voltmeter of any suitable
known construction may be connected in parallel to the circuit between A¹
and A'.
The essential feature of the invention of course remains the same if other
potential indicators such as voltmeters are substituted for the lamps. The same
arrangements can also be used for transformed pressures if with high pressures in
the machines a transformation should be desirable.
If, at a central station, a considerable number of machines have to be connected
in parallel, it is sufficient to provide a single set of glow lamps.
Thus if three machines are to be connected in parallel to the network through
the bus bars A B C Fig. 3, three leads from these bars are arranged to pass
through the glow lamp device G to the contacts a, b, c, opposite which are
arranged the contacts a', b', c¹, a³, b, c, a³, b, c, which are connected to the
terminals of the several machines. The three glow lamps are arranged in a cycle
whereby the direction of the lighting up can be more readily seen. If the
machine I is to be connected to the network, the contacts a, b c are first
connected with the contacts a b c by a suitable three pole plug. A voltmeter
is introduced parallel to the lamp in the circuit A A' for indicating the phases.
For the purpose of more sharply indicating the direction in which the lamps are
consecutively brought to incandescence there may be provided more than three
lamps with consecutive incandescence. This may be effected for example with
machines with star grouping by utilising, in addition to the potentials at the free
terminals, that at the common point of union.
Fig. 4 shews one of the many possible arrangements for five lamps. These
lamps are connected between A' A', B' C, B' O', B' C¹, C₁ O³.
The lamp between A' A is the indicator lamp, on the extinguishing of which
the machines can be connected in parallel.
The arrangement above described by way of example for a three phase machine
can also be employed for polyphase currents generally.
Fig. 5 shews for example the connections for a two phase machine with star
grouping and three lamps.
The lamp in circuit B B is the phase indicator.
For connecting single phase machines in parallel the described arrangement is
not directly applicable, as three glow lamp circuits with relatively shifted phases
are necessary. The arrangement can be used if three circuits with shifted phases
can be produced, not necessarily shifted 120° relatively to each other.
With alternate current machines in which the terminal potential can be divided
into two opposite potentials relatively shifted as regards their phase, the method
can be employed by using common point of union of the groupings. Thus for
instance in Fig. 6 A B and A B are the terminals of the alternate current
machines A¹ O, B' O' and A' O', B2 O, the potentials to the zero point, of which
the potentials A' O' are shifted relatively to B' O' through 120°, as are also A³ O*

page_text: A'B' E
E
A¹ O' =
E
B¹ O' =
In Fig. 7 are indicated the amplitudes of the potentials together. with the shifted
phases, A¹ O' is shifted relatively to B' O' 120°, B¹ O' relatively to A' B¹ 30°.
With alternate current machines in which the sections of the winding are so
arranged in grooves that windings in contiguous grooves have potentials of different
phase produced in them, there may be obtained two potential circuits with two
potentials shifted relatively to each other as regards phase by a suitable connection
of the main winding, if necessary with the use of an auxiliary winding laid in the
grooves.
By combination similar to that shewn at Fig. 7 there are obtained three
potentials shifted in phase relatively to each other, which can be used for working
the above described arrangement.
If with alternate current machines the windings are only situated in two thirds
of the grooves, while one third are left free, an auxiliary winding can be wound
in the free grooves or in a portion thereof.
This winding then has a phase shifted 90° relatively to the main winding.
The potential of the auxiliary winding can then be combiued with the main
winding or a part of.the main winding.
If in Fig. 8, A B E be the potential of the main winding, C D = E' that of
the auxiliary winding, then on connecting.C and B three conductors are obtained
between which exist the potentials A B E', BDE, AD = (E-E).
These conductors can be used for connecting in parallel in the same way as
in Fig. 6.
The amplitudes and shifting of the phases of the several potentials A B, BD,
DC, and AD are shewn at Fig. 9.
With the alternate current machines in which it is not possible to take off
potentials with shifted phases, as also with existing alternate current installations
in which the above described third conductor is not available, the described
arrangement for connecting in parallel can be used with the aid of an auxiliary
apparatus.
Let A and B Fig. 10 be the poles of an alternate current machine.
To the machine terminals a transformer T, in the primary circuit of which a
choking coil J is connected. The potential E FBC is then shifted as regards
its phase relatively to the potential A B. By combination of the two potentials
Fig. 11, there are obtained the three terminal potentials A B, BC=EF, and
AC (A B-E F).
These three potentials can be used for working the device for connecting in
parallel alternate current machines.
The choking coil J and the transformer T can easily be combined in one and the
same apparatus. In place of the choking coil a condenser can also be used.
With rotary current or alternate current machines working with high potential
it is generally not expedient to connect the potential indicators such as volt meters,
glow lamps &c. to the high potential circuit, in such cases it is of advantage to
transform the high potential.
For such transformation a single transformer is sufficient with suitable arrange-
ments. In Fig. 12 A B C shew the bus bars to which the terminals A B C of a
rotary current machine I are connected.

page_text: A B C are the terminals of the rotary current machine II to be connected in
parallel with the network.
A transformer T is so connected that the terminal a' leads to the bar A, a² to C
a² to B, and the terminals respectively to the terminals A B C
The secondary or low-tension windings are closed by glow lamps G¹ G³ G³.
These glow lamps are brought successively to incandescence with asynchronous
motion of the machines. With synchronism and equality of phase of the machines
the lamp G remains dark. In this condition the machine II can be connected
in parallel with the network by means of the three-pole switch. The trans-
former T is in this case permanently connected to the network by means of the
terminals a' a³ a³.
The terminals e e e are ordinarily open. When a machine is to be connected
in parallel, its terminals are connected in any suitable manner with the terminals of
the transformer.
By way of example, as shewn in Fig. 12, leads may pass from the three
terminals e e e to three bus bars, so that by means of three-pole switches the
several machines can be readily connected.
The rotary current transformer shewn at Fig. 12 only has to transform the
energy for the three glow lamps G G G and can therefore be very small. For
high potentials the transformers would have to be made larger; to avoid this,
lower potentials can be taken from part of the winding of the high tension machine
for working the said devices. For enabling the apparatus to be safely manipulated,
it is in this case, of advantage to separate the low potential circuit completely from
the high potential circuit. This is effected by interposing a so called insulation
transformer, the transformation ratio of which can be 1: 1. The transformer can
then be small and of safe action.
For working the parallel connecting device it is connected in the same way as
shewn at Fig. 12 for a reducing transformer.
For alternate current machines the arrangement can of course be one of those
previously described.
In place of the glow lamps or voltmeters an electromotor can be used as an
indicator suitably connected with the circuits.
This motor will then rotate either clockwise or counter clockwise, according as
the one or the other machine runs too fast or too slow. With synchronous motion
it remains stationary, or oscillates slightly round an equilibrium position. Fig. 13
shews such an arrangement by way of example.
The two machines I and II to be connected in parallel have terminals A¹ B₁ C',
and AB C. The rotary current motor D has three separate windings a¹ el, a² e³,
ae. A¹ is connected with a', B' with a, C¹ with a, A with e¹, B with e
C² with e'. For increasing the moment of the rotary current a resistance W is
introduced in front of the winding of the rotating part.
If it be desired to reduce the potential for the motor, which, in consequence of
the interference action, is only supplied with potential of few periods, a transformer
arranged similar to that shewn at Fig. 12 can be used. Of course the arrangement
can be used in suitably modified form also for alternate current or polyphase
'machines.
As the motor rotates clockwise or counter-clockwise according as the machine
to be connected in parallel runs too fast or too slow, the motor can be directly
used for acting by means of suitable devices upon the regulating mechanism, of the
steam engine, turbine or other driving motor einployed.
For example, with steam engines, the regulator can be so controlled that according
as the motor rotates clockwise or counter-clockwise, the steam supply will be more
or less throttled.
The described devices for connecting in parallel single or polyphase alternate
current machines, can of course be employed for other purposes in which it is
desired to ascertain the synchronism of machines or parts of machines. Thus

page_text: for example the described arrangements can be employed for starting synchronous
motors.
Alternate current motors in which the field magnet windings are supplied from a
separate source of current are first brought to synchronism before they are connected
to the network.
The synchronous motor consequently runs as a dynamo, as long as it is not
connected to the network. On connecting it to the network therefore the same
conditions hold good as with the connecting in parallel of the dynamos, that is to
say, the synchronous motor must not only run synchronously with the primary
machine but also with equal phases.
If the synchronous motor is not connected at the moment of synchronism and
equality of phase, the same disadvantages arise as with parallel connection of two
dynamos that are asynchronous or of unequal phase, which is detrimental for the
network, in particular in the case when the synchronous motor has to run parallel
with other motors, such as steam engines, at a secondary station. In this case the
above described arrangements indicate at the secondary station the direction in
which the synchronous motor requires to be regulated, and the proper moment for
connecting it to the network.
Datod this 6th day of February 1806
ABEL & IMRAY,
Agents for the Applicans.
Method and Apparatus for Effecting the Connection in Parallel of
Alternate Current and Polyphase Dynamos and Motors.
We, SIEMENS BROS. & 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:-
As is well known, alternate current dynamos or rotary current dynamos before
being connected in parallel to the supply circuit must be brought into synchronism.
In order to ascertain such synchronism, glow lamps are usually employed
connected between the corresponding terminals of the machines; the extinguishing
of such lamps then affords the indication of the correct time for connecting in
parallel. This arrangement is subject to the disadvantage that it does not indicate
whether the machine to be connected in parallel is running too fast or too slow, as
in both cases the same indication is given, namely a fluctuation in the light of the
glow lamps.
This materially complicates the connecting in parallel as it cannot be ascertained
in what direction the speed has to be adjusted.
The present invention relates to means whereby it can be readily ascertained
with respect to two machines that require to have synchronous motion, firstly,
which of the machines is running too fast or too slow and secondly when
synchronism has been attained.
We will describe the said invention with reference to the diagrammatic drawings
accompanying our Provisional Specification in which Fig. 1 shews the mode of
connection heretofore employed for example for a rotary current dynamo. A'B'C'
and A'B'C', are the terminals of the machines to be connected in parallel. The
glow lamps indicated by crosses are connected between the corresponding terminals
namely between A' and A', B' and B2, C1 and C³.

page_text: The machines can be connected in parallel by closing the three pole switch D
when the potentials at the said corresponding terminals are equal. The proper
moment for doing this is ascertained when the glow lamps are extinguished.
Fig. 2 shews an essentially different mode of connection ac ording to the present
invention the glow lamps not being connected to corresponding terminals of the
rotary current machines."
The one lamp is connected between A¹ and A' but the second is connected
between C and B2 and the third between B and C. With this arrangement in
consequence of the interference of the impulses, of the electro motive force, the
lamps do not glow simultaneously but consecutively, when the machines are not in
step. The order of sequence of such incandescence depends upon whether the
machine to be connected in parallel lags behind or is ahead of synchronism.
Consequently the said order of sequence affords a test for ascertaining which
machine runs faster or slower and a single trial will enable the operator to
determine whether the machine to be connected in parallel runs too fast or
too slow.
With the arrangement at Fig. 2 the one lamp being connected between
corresponding terminals A' and As of the machines, the switch D can be closed
at the moment when the potentials at A¹ and A2, B1 and B2, C1 and C coincide as
to phase and amplitude. The potential difference between A' and A' is then equal
to zero, and the corresponding lamp is extinguished while the other two glow with
about one half the normal brightness, consequently the extinguishing of the lamp
between A and A' indicates the proper moment for connecting in parallel. In
order to indicate this moment still inore accurately a volt meter of any suitable
known construction may be connected in parallel to the circuit between A'
and A³.
The essential feature of the invention of course remains the same if other
potential indicators such as voltmeters are substituted for the lamps. The same
arrangements can also be used for transformed pressures if owing to high pressures
in the machines a transformation should be desirable.
If, at a central station a considerable number of machines have to be connected
in parallel, it is sufficient to provide a single set of glow lamps.
Thus if three machines are to be connected in parallel to the network through
the bus bars ABC Fig. 3, three leads from these bars are arranged to pass
through the glow lamp device G to the contacts a, c, b, opposite which are arranged
the contacts a¹, b, c, a², b, c, a, b, c, which are connected to the terminals of the
several machines. The three glow lamps are arranged in a cycle whereby the
If the machine I is to be
direction of the lighting up can be more readily seen.
-connected to the network, the contacts a, c, bare first connected with the
contacts a, b, c, by a suitable three pole plug. A voltmeter is introduced parallel
to the lamp in the circuit A A¹ for indicating the phases. For the purpose of
more sharply indicating the direction in which the lamps are consecutively brought
to incandescence there may be provided more than three lamps with consecutive
incandescence. This may be effected for example with machines with star
grouping by utilising, in addition to the potentials at the free terminals, that
between the several terminals and the common point of union.
Fig. 4 shews one of the many possible arrangements for five lamps. These lamps
are connected between A¹ A, B¹ C³, B³, O', B'C', CO. The lamp between A' A' is
the indicator lamp, on the extinguishing of which the machines can be connected in
parallel.
The arrangement above described by way of example for a three phase machine
can also be employed for polyphase currents generally.
Fig. 5 shews for example the connections for a two phase machine with star
grouping and three lamps. The lamp in circuit B1 B2 is the phase indicator.
For connecting single phase machines in parallel the described arrangement is
not directly applicable, as three glow lamp circuits with relatively shifted phases
are necessary.

page_text: The arrangement can be used if three circuits with shifted phases can be
produced, not necessarily shifted 120° relatively to each other.
With alternate current machines in which the terminal potential can be split up
into two potentials relatively shifted in opposite directions as regards their phase,
the method can be employed by using the common point of union of the groupings.
Thus for instance in Fig. 6 A B and A B are the terminals of the alternate
current machines A' O, B' O' and A' O, B' O' the potentials at the zero point
from which the potential A¹ O' is shifted relatively to B¹ O' through 120° as is
also A O relatively to B2 0. Then using the leads from the zero point, there.
will ha the three natantial differences
In Fig. 7 are indicated the amplitudes of the potential differences together with
the shifted phases A¹ O is shifted relatively to B O 120°, B' O relatively
to A' B¹ 30°.
With alternate current machines in which the sections of the winding are so
arranged in grooves that windings in contiguous grooves have potentials of differing
phase produced in them, there may be obtained two potential circuits with two
potentials shifted relatively to each other as regards phase by a suitable connection
of the main winding if necessary with the use of an auxiliary winding laid in the
grooves.
By combination similar to that shewn at Fig. 7 there are obtained three potentials
shifted in phase relatively to each other which can be used for working the above.
described arrangement.
If with alternate current machines the windings are only situated in two thirds.
of the grooves, while one third are left free, an auxiliary winding can be wound in,
the free grooves or in a portion thereof.
This winding then has a phase shifted 90° relatively to the main winding.
The potential of the auxiliary winding can then be combined with the main
winding or a part of the main winding.
If in Fig. 8 A BE be the potential difference of the main winding C D = E
that of the auxiliary winding, then on connecting C and B three conductors are
obtained between which exist the potential differences AB = E¹, BD = E³,.
AD (E-E³).
These conductors can be used for connecting in parallel in the same way as in
Fig. 6. The amplitudes and shifting of the phases of the several potentials A B,
BD DC and A D are shewn at Fig. 9.
In the case of alternate current machines in which it is not possible to take off
potentials with shifted phases as also with existing alternate current installations.
in which the above described third conductor is not available the described.
arrangement for connecting in parallel can be used with the aid of an auxiliary
apparatus.
Let A and B Fig. 10 be the poles of an alternate current machine.
Across the machine terminals is connected a transformer T, in the primary
circuit of which is a choking coil J. The potential difference EF = BC is then
shifted as regards its phase relatively to the potential difference A B. By com-
bination of the two potentials Fig. 11, there are obtained the three terminal
potentials A B, BC=EF, and AC = (AB-EF). These three potentials
can be used for working the device for connecting in parallel alternate current.
machines.

page_text: The choking coil J and the transformer T can easily be combined in one and
the same apparatus. In place of the choking coil a condenser can also be used.
With rotary current or alternate current machines working with high potential
it is generally not expedient to connect the potential indicators such as volt-meters,
glow lamps, &c. to the high potential circuit, in such cases it is of advantage to
transform the bigh potential.
For such transformation a single transformer is sufficient with suitable
arrangements.
In Fig. 12 ABC shew the bus bars to which the terminals A B C₁ of a
polyphase machine I are connected.
A B C are the terminals of the polyphase machine II to be connected in
parallel with the network.
A transformer T is so connected that the terminal a' leads to the bar A, a' to C,
a to B, and the terminals e¹e e respectively to the terminals A' B'C'.
The secondary or low-tension windings are closed through glow lamps G'G' G*.
These glow lamps are brought successively to incandescence with asynchronous
motion of the machines. With synchronism and equality of phase of the machines
the lamp G' remains dark. In this condition the machine II can be connected in
parallel with the network by means of the three-pole switch. The transformer T
is in this case permanently connected to the network by means of the
terminals a' a³ a³. ·
The terminals e¹e are ordinarily open. When a machine is to be connected
in parallel, its terminals are connected in any suitable manner with the terminals
of the transformer.
By way of example, as shewn in Fig. 12, leads may pass from the three
terminals e e e to three bus bars, so that by means of three-pole switches the
several machines can be readily connected.
The polyphase transformer shewn at Fig. 12 only has to transform the energy
for the three glow lamps G¹ G G³ and can therefore be very small.
For high potentials the transformers would have to be made larger; to avoid this,
lower potentials can be taken from part of the winding of the high tension machine
for working the said devices. For enabling the apparatus to be safely manipulated,
it is in this case, of advantage to separate the low potential circuit completely from
the high potential circuit. This is effected by interposing a so called insulation
transformer, the transformation ratio of which can be 1: 1. The transformer can
then be small and of safe action. For working the parallel connecting device it is
connected in the same way as shewn at Fig. 12 for a reducing transformer.
For alternate current machines the arrangement can of course be one of those
previously described.
In place of the glow lamps or voltmeters an electromotor can be used as an
indicator suitably connected with the circuits.
This motor will then rotate either clockwise or counter clockwise, according
as the one or the other machine runs too fast or too slow. With synchronous
motion it remains stationary, or oscillates slightly round an equilibrium position.
Fig. 13 shews such an arrangement by way of example.
The two machines I and II to be connected in parallel have terminals A B C
and A'B'C'. The rotary current motor D has three separate windings ale, a² e
a³ ³ A is connected with a', B' with a, C with a³, A' with e', B with, C
with e. For increasing the moment of the rotary current a resistance W is
introduced in front of the winding of the rotating part.
If it be desired to reduce the potential for the motor, which, in consequence of
the interference action, is only supplied with potential of low frequency, a trans-
former arranged similar to that shewn at Fig. 12 can be used. Of course the
arrangement can be used in suitably modified form also for alternate current or
polyphase machines.
The described devices for connecting in parallel single or polyphase alternate
current machines, can of course be employed for other purposes in which it is

page_text: desired to ascertain the synchronism of machines or parts of machines. Thus:
for example the described arrangements can be employed for starting synchronous
motors.
Alternate current motors in which the field magnet win lings are supplied from
a separate source of current are first brought to synchronism before they are
connected to the network.
The synchronous motor consequently runs as a dynam, as long as it is not:
connected to the network. On connecting it to the network therefore the same
conditions hold good as with the connecting in parallel of dynamos, that is to say,.
the synchronous motor must not only run synchronously with the primary machine:
but also be in phase with it.
If the synchronous motor is not connected at the moment of synchronism and'
equality of phase, the same disadvantages arise as with parallel connection of two-
dynamos that are asynchronous or of unequal phase, which is detrimental for the-
network, in particular in the case when the synchronous motor has to run parallel
with other motors, such as steam engines, at a secondary station. In this case.
the above described arrangements indicate at the secondary station the direction.
in which the synchronous motor requires to be regulated, and the proper moment.
for connecting it to the network.
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:-
1. A method of facilitating the connection in parallel of single or polyphase.
alternate current machines, consisting in so connecting circuits having three or
more glow lamps between the terminals having different phases of the machines
to be connected in parallel, that the sequence of the consecutively occurring.
incandescence of the glow lamps during asynchronous motion will indicate which
of the machines is running faster or slower than the other, substantially as.
described.
2. An arrangement for carrying out the method of facilitating connection in.
parallel referred to in the first claim, consisting in connecting one of the glow
lamp circuits between the equal-phase points of the machines to be connected in.
parallel, so that the equal-phase synchronism of the machines is indicated by the
extinction of the lamp, substantially as described.
3. The arrangement for applying the methods of connection referred to in.
Claims 1 and 2, to single phase alternate current machines, wherein the necessary
three circuits of different phase are obtained by taking currents from three points.
of the winding which have respectively a different potential, substantially as
described.
4. The arrangement for applying the method of connection referred to in.
Claims 1 and 2 to single phase alternate current machines, wherein the necessary-
three circuits of different phase are obtained by the combination of the main
winding and an auxiliary winding of shifted phase, substantially as described.
5. The arrangement for applying the method of connection referred to in
Claims Nos. 1 and to single phase alternate current machines, wherein the
necessary three circuits of different phase are obtained by means of condensers or
induction coils and current transformers, substantially as described.
6. An arrangement for carrying out the method of facilitating the connection-
in parallel referred to in Claims Nos. 1 and 2, wherein the phase lamps are.
included in the secondary circuit of a current transformer the primary circuit of
which is partly connected between corresponding terminals and partly between
non-corresponding terminals of the two machines to be connected in parallel,
substantially as described.
7. An arrangement for carrying out the method of facilitating the connection
in parallel referred to in Claims Nos. 1 and 2, wherein the glow lamps are-
Н

page_text: replaced by the windings of an electromotor, whose direction of rotation will
indicate which machine runs at the quicker speed, substantially as described.
8. The application of the arrangements set forth in Claims Nos. 1 to 7, for the
connecting of single or polyphase synchronous alternate current motors to a
network, substantially as described.
ABEL & IMRAY,
Agents for the Applicants.