An Improved Switching-apparatus for Preventing Self-induction Sparks from being formed during the Operations of Disconnecting and Reversing Electromotors.
Year: 1897

page_text: PROVISIONAL DILUIFICATION.
An Improved Switching-apparatus for Preventing Self-induction
Sparks from being formed during the Operations of Disconnecting
and Reversing Electromotors.
I, ERNST EGGER, of 187, Simmeringerstrasse, Vienna, in the Empire of Austria-
Hungary, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to an improved switching apparatus, by means of which
-under avoidance of any special resistances the opening-spark, arising from
the magnet-coil or windings and from the armature, during the operations of dis-
connecting or reversing shunt-wound electro-motors, is prevented from forming.
According to this invention the switching-apparatus is so arranged that, with-
out any special parts being required at the moment of disconnecting the motor
from the circuit, the magnet windings remain connected with the armature,
through the windings of which latter the current induced from the coils of the
magnet passes and is lost therein, so that the opening-spark of the current is
avoided.
In this operation the self-induction current traverses any resistances that may
be inserted into the conductor of the armature and which resistances, ou connect-
ing and disconnecting the motor, are in the usual manner temporarily included
into the circuit of the armature.
Moreover the switching-apparatus is so constructed that, on reverting the
motor, the armature with its appertaining and included resistances, above referred
to, remains short-circuited in itself, so that, however rapidly the reversing opera-
tion may be effected, the generation of self-induction sparks is rendered impos-
sible.
A switching-apparatus constructed in conformity with this invention, also a
mechanism for operating the same, are represented in the accompanying drawing,
in which
Figs. 1 to 4 and 1 to 4 show the method of switching in the different stages
of connecting, disconnecting and reversing, the arrangement of the drawing being
such that two figs. of equal numbers with and without index letters always repre-
sent the respective connections of the switching-apparatus for both rotary direc-
tions of the electromotor. Figs. 5 and 6 represent a top-view and cross section,
respectively, of the apparatus. In all figures similar letters refer to similar
parts.
The armature of the motor and the magnet windings are diagrammatically
represented by the letters A and B, respectively. The current is supplied through
the conductors I and II and passes in the direction, indicated by the arrows.
In the particular state of connection represented in Fig. 4 for one rotary direc
tion and in Fig. 4^ for the other direction of the electromotor the resistances CD
are disconnected

page_text: In order to disconnect the electromotor, first of all the resistances CD are
successively inserted into the circuit a a¹ of the armature A (Fig. 3) by means of
the switching-apparatus, thereupon the feed-current-conductors I II are discon-
nected, whilst the field-magnet and armature windings, remain connected with
each other for the purpose of preventing self-induction sparks from forming as
above stated, so that the magnet windings remain, as it were short-circuited, since
the resistance offered by the armature and by the included resistance, is com-
paratively speaking small. On reversing the motor a short-circuiting connec-
tion y (Figs. 1 and 14) is moreover made between the poles of the armature,
which, as stated, renders the formation of a self-induction spark even upon the arma-
ture itself impossible, however rapidly the reversing operation may take place. The
connection y remains closed (Fig. 1), until, for the purpose of reversing the
motor, the intermediate conductors a a have been connected to the opposite poles
of the armature (Fig. 2).
Thereupon the conductors I II are again inserted (Fig. 3^), and the motor
then at once starts in the other direction; and finally the resistances CD are
again successively disconnected (final-position 4^).
These seven different stages of connection (Fig. 1 and Fig. 1^ being identical)
are attained with this switching apparatus by turning one single handle.
The current-feed (Figs. 5 and 6) takes place through the conductors I II and the
current is thus conveyed to the double feed plates EF, each pair of which is
upon each side connected by an intermediate conductor ef. The circuit to the
armature of the motor is formed by the two conducting wires a a¹, one of which
passes to the lower exterior plate G while the other is connected to the upper
plate H. Moreover at each end of this plate an additional pair of plates H¹H³
are arranged, each pair of which are connected by wires h¹h and are connected
in series relatively to each other and to the upper plate H by means of the
wires h³ h h h and the two intermediate resistance-coils CD.
The magnet coil B is connected to the contacts 62 upon the board of the switch-
ing apparatus by means of the two wires bb. From the two contacts two insu-
lated conducting cables 63 pass through the openings 6 of the board and, after
a few windings about the centre pivot of the switching-apparatus, they lead to
the two contact plates L L'. These contact plates L L' are each slid upon two
guide pins which are fixed and insulated upon the switch-lever K, and are
through the medium of the springs pressed elastically against the plates of
the switching-apparatus, over which plates they will, on turning the switch-
lever, slide along with certain clastic pressure thus closing the circuit between
the two plates, whilst the flexible conducting cables wound about the pivot k
establish the permanent connection between the moving contact-plates LL' and
the conductors bb leading to the magnet-windings B.
The function of the apparatus will be clearly understood on merely comparing
the diagrammatic figures with each other. In order that the comparison may be
more readily made, the positions of the switch-lever K, which correspond to the
different switching stages, represented in Figs. 1 to 4 and 1 to 4^, have been
marked with the same letters as the appertaining figures.
The lever K, in Fig. 5, occupies the position, corresponding to Figs. 1 to 1^,
respectively, and the short-circuit y, represented diagrammatically in Figs. 1
and 1 is in reality obtained on the apparatus by means of the contact plates LL¹
connecting the plates G and H.
4
4
When the lever K is turned in the direction, in which a hand travels upon the 5
dial of a watch, it successively arrives at the positions 2, 3 and 4. In the position 2,
as clearly shown, the magnet conductor bb, through the medium of the cables b³
and of the contact-plates L, is connected at the left hand top part with the
plate H2 and thence over the resistances CD, connected in series, over the
plates H¹, and H with the one wire a¹ and through the medium of the contact 5
plate L, over the lower plate G with the other wire a of the armature winding.
(Connection corresponding to Fig. 2).

page_text: When the lever, lastly, arrives at the position 3, then the contact-plates LL¹
connect the current-feed-plates EF with the plates H2 and G.
As to be seen, the magnet windings as well as the armature windings of the
motor are now included in the circuit I, II; the armature windings comprising
the included resistance of the two wire coils CD. On continuing to turn the
lever K, until the contact-plate L arrives opposite the plate H¹, the lower resist-
ance coil C has already been disconnected; and when finally the lever K and the
contact-plates LL' arrive at the position 4, then also the connection, represented
in Fig. 4 is attained, in which the motor is completely connected.
When the lever K is returned the connecting stages, of course, take place in
the reversed order and is clearly shown, on again arriving at the position 2,
the current-feed is again interrupted and the armature is short-circuited rela-
tively to the magnet-windings; and finally in position 1 the armature with the
starting resistance is directly short-circuited by the contact-plates LL', which
in this case connect the plates G and H².
When the lever K is turned out of the position 1 in the other direction, it
successively arrives at the connecting positions 1° to 4ª corresponding to Figs. 1^
to 4, in which operation the process above described is exactly repeated, the only
difference being that the direction of the current in the armature and conse-
quently also the rotary direction of the motor is reversed.
It is evident that the number of the intermediate plates H¹H2 as well as the
number of the appertaining resistances CD included, is absolutely unimportant
with regard to the inventive idea and it goes without saying that in the case of
large motors a comparatively large number of intermediate resistances with their
appertaining plates, and in the case of smaller types of motors a comparatively
smaller number or none at all are or may be employed.
00
1004
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.
An Improved Switching-apparatus for Preventing Self-induction
Sparks from being formed during the Operations of Disconnecting
and Reversing Electromotors.
I, ERNST EGGER, of 187, Simmeringerstrasse, Vienna, in the Empire of Austria-
Hungary, Engineer, 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 an improved switching apparatus, by means of which
-under avoidance of any special resistances the opening-spark, arising from
the magnet-coil or windings and from the armature, during the operations of dis-
connecting or reversing shunt-wound electro-motors, is prevented from forming.
According to this invention the switching-apparatus is so arranged that, with-
out any special parts being required at the moment of disconnecting the motor
from the circuit, the magnet windings remain connected with the armature,
through the windings of which the current induced from the coils of the magnet
passes and is lost therein, so that the opening-spark of the current is avoided.
In this operation the self-induction current traverses any resistances that may
be inserted into the conductor of the armature and which resistances, on connect-

page_text: ing and disconnecting the motor, are in the usual manner temporarily included
into the circuit of the armature.
Moreover the switching-apparatus is so constructed, that, on reversing the
motor, the armature with its appertaining and included resistances, above referred
to, remains short-circuited in itself, so that, however rapidly the reversing opera-
tion may be effected, the generation of self-induction sparks is rendered impos-
sible.
A switching-apparatus constructed in conformity with this invention, also a
mechanism for operating the same, are represented in the drawings accompanying
the Provisional Specification such drawings being herein referred to and in
which:
Figs. 1 to 4 and 1 to 4* show the method of switching in the different stages
of connecting, disconnecting and reversing, the arrangement of the drawing being
such that always two figs. of equal numbers with and without index letters repre-
sent the respective connections of the switching-apparatus for both rotary direc-
tions of the electromotor. Figs. 5 and 6 represent a plan and cross section,
respectively, of the apparatus. In all figures similar letters refer to similar parts.
The armature of the motor and the magnet windings are diagrammatically
represented by the letters A and B, respectively. The current is supplied through
the conductors I and II and passes in the direction, indicated by the arrows.
In the particular state of connection represented in Fig. 4 for one rotary direc-
tion and in Fig. 4 for the other direction of the electromotor the resistances CD
are disconnected.
In order to disconnect the electromotor, first of all the resistances CD) are
successively inserted into the circuit a a¹ of the armature A (Fig. 3) by means of
the switching-apparatus, thereupon the feed-current-conductors I II are discon-
nected, whilst the field-magnet and armature windings, remain connected with
each other for the purpose of preventing self-induction sparks from forming as
above stated, so that the magnet windings remain, as it were short-circuited, since
the resistance offered by the armature and by the included resistance, is com-
paratively speaking small. On reversing the motor a short-circuiting connec-
tion y (Figs. 1 and 1^) is moreover made between the poles of the armature,
which, as stated, renders the formation of a self-induction spark even upon the arma-
ture itself impossible, however rapidly the reversing operation may take place. The
connection y remains closed (Fig. 1^), until, for the purpose of reversing the
motor, the intermediate conductors a a¹ have been connected to the opposite poles
of the armature (Fig. 2^).
Thereupon the conductors I II are again inserted (Fig. 3*), and the motor
then at once starts in the other direction; and finally the resistances CD are
again successively disconnected (final-position 4*).
These seven different stages of connection (Fig. 1 and Fig. 1ª being identical)
are attained with this switching-apparatus by turning a single handle.
The current-feed (Figs. 5 and 6) takes through the conductors I II and the
current is thus conveyed to the double feed plates EF, each pair of which is
upon each side connected by an intermediate conductor ef. The circuit to the
armature of the motor is formed by the two conducting wires a a¹, one of which
passes to the lower exterior plate G while the other is connected to the upper
plate H. Moreover at each end of this plate an additional pair of plates H¹H²
are arranged, each pair of which are connected by wires h¹² and are connected
in series relatively to each other and to the upper plate H by means of the
wire h³hhh and the two intermediate resistance-coils CD.
The magnet coil B is connected to the contacts 62 upon the board of the switch-
ing apparatus by means of the two wires bb. From the two contacts two insu-
lated conducting cables 63 pass through the openings 64 of the board and, after
a few windings about the centre pivot k of the switching-apparatus, they lead to
the two contact-plates LL. The contact-plates LL are each slid upon two guide
pins, which are fixed and insulated upon the switch-lever k by screwing them

page_text: into bars 12 secured to lever by screws 13 and insulated therefrom by strips
of suitable material. The pins are through the medium of the springs
pressed elastically against the plates of the switching-apparatus, over which
plates they will, on turning the switch-lever, slide along with certain elastic
pressure thus closing the circuit between the two plates, whilst the flexible con-
ducting cables wound about the pivot kestablish the permanent connection
between the moving contact-plates LL' and the conductors 66' leading to the
magnet-windings B.
The function of the apparatus will be clearly understood on merely comparing
the diagrammatic figures with each other. In order that the comparison may be
more readily made, the positions of the switch-lever K, which correspond to the
different switching stages, represented in Figs. 1 to 4 and 14 to 4*, have been
marked with the same letters as the appertaining figures.
The lever K, in Fig. 5, occupies the position, corresponding to Figs. 1 and 1^,
respectively, and the short-circuit y, represented diagrammatically in Figs. 1
and 1 is in reality obtained on the apparatus by means of the contact plates LL'
connecting the plates G and H.
When the lever K is turned in a clockwise direction by means of a hand
wheel k¹, it successively arrives at the positions 2, 3 and 4. In the position 2,
as clearly shown, the magnet conductor 6 6, through the medium of the cables ³
and of the contact-plates L, is connected at the left hand top part with the
plate H2 and thence over the resistances CD, connected in series, over the
plates H', and H with the one wire a¹ and through the medium of the contact-
plate L, over the lower plate G with the other wire a of the armature winding.
(Connection corresponding to Fig. 2.)
When the lever, lastly, arrives at the position 3, then the contact-plates LL¹
connect the current-feed-plates EF with the plates H2 and G.
As to be seen, the magnet windings as well as the armature windings of the
motor are now included in the circuit I, II; the armature windings comprising
the included resistance of the two wire coils CD, on continuing to turn the
lever K, until the contact-plate L arrives opposite the plate H¹, the lower resist-
ance coil C has already been disconnected; and when finally the lever K and the
contact-plates LL' arrive at the position 4, then also the connection, represented
in Fig. 4 is attained, in which the motor is completely connected.
When the lever K is returned the connecting stages, of course, take place in
the reversed order and as is clearly shown, on again arriving at the position 2,
the current-feed is again interrupted and the armature is short-circuited rela-
tively to the magnet-windings; and finally in position 1 the armature with the
starting resistance is directly short-circuited by the contact-plates LL', which
in this case connect the plates G and H2
When the lever K is turned out of the position 1 in the other direction, it
successively arrives at the connecting positions 1 to 4", in which operation the
process above described is exactly repeated, the only difference being that the
direction of the current in the armature and consequently also the rotary direc-
tion of the motor is reversed.
It is evident that the number of the intermediate plates H¹H³ as well as the
number of the appertaining resistances CD included, is absolutely unimportant
with regard to the inventive idea and it is evident that in the case of large
motors a comparatively large number of intermediate resistances with their apper-
taining plates and in the case of smaller types of motors a comparatively smaller
number or none at all are or may be employed.
Having now particularly described and ascertained the nature of my said
nvention and in what manner the same is to be performed I declare that what
I claim is:-
1. A switching apparatus for preventing the formation of self-induction snarks
j

page_text: during the operations of disconnecting and reversing electromotors; the charac-
teristic feature of this apparatus being that the magnet-windings 661 of the
motor, on disconnecting the circuit III remains short-circuited together with
the conductor aa', of the armature A and that the said armature itself remains
short-circuited during the operation of reversing the same with its starting resist-
ance CD), so that during the disconnecting operation the self-induction current
of the magnet windings finds its way through the armature windings and that
during the reversing operation the induction spark is prevented from forming,
owing to the short-circuit y.
2. In a switching-apparatus of the kind, ascertained in the first claim: the
arrangement of two movable contact-plates LL' which form the terminals of the
conductors bb leading to the magnet-windings B and which, for the purpose of
connecting and disconnecting the motor, produce four connecting stages to 4
in such a manner that, in the fourth position, when the motor is connected, they
effect the connection between the current-feed plates EF and the plates GH
joined to the armature windings a al, and of which contact-plates, during the
operation of disconnecting, according to the third position, always one, for
instance L, successively sliding over the plates H1 H2, inserts the resistances CD
into the armature shunt-circuit, whilst the other for instance L¹, sliding over the
plate G, closes the armature-circuit a a¹; until according to the second position,
the first mentioned plate L leaves the current-feed-plate F but still remains upon
the armature-current-plate H2, thus offering the self-induction current in the
magnet B during the operation of disconnecting the current feed plates EF-a
passage through the armature windings A; whereupon, finally, according to the
first position, the contact-plates LL' connect the plates H2 and G, thus short-
circuiting the armature A with its starting resistance CD; whereas, during the
reversing operation, the contact-plates LL', in the different connecting stages 1ª
to 4", exchange their functions in order to cause the motor to rotate in the other
direction.
Dated this "1st doy of Sentember 1898
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, Agents.