Regulating Apparatus for Electro Motors.
Year: 1893

page_text: Date of Application, 20th Nov., 1893
Complete Specification Left, 14th July, 1894-Accepted, 18th Aug., 1894
PROVISIONAL SPECIFICATION.
[Communicated from abroad by BERLINER MASCHINENBAU AKTIEN GESELL-
SCHAFT vorm. L. SCHWARTZKOPFF, of Chauseestrasse 17/18, Berlin,
Germany.]
Regulating Apparatus for Electro Motors.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery Lane,
in the County of London, Consulting Engineer and Chartered Patent Agent, do
hereby declare the nature of this invention to be as follows:-
For the purpose of regulating the speed of electro motors it has been customary
hitherto either to divide the armature winding, and, according to requirements, to
connect the separate parts either in parallel, or in series, or the windings of the
field magnets have had their exciting action varied by the interposition of
resistances. Both methods of regulating suffer from the defect that with the
alteration of the connections there always occurs an alteration in the position of
the neutral axis, causing the brushes to produce sparking and requiring them to be
shifted in accordance with the changed position of the neutral axis.
The present invention relates to a method of connecting electro motors wherein
this disadvantage is obviated by simultaneously so altering the connections of the
armature winding and the strength of the field magnet winding that the position of
the neutral axis remains unaltered, and that consequently no shifting of the brushes
after each regulation of the speed is required.
In addition, by the alteration of the connections of the armature winding jointly
with that of the field magnet winding the advantage of a greater range for the
variation of the speed is obtained.
If for example, the armature winding be divided into two parts which can either
be connected in parallel or in series, or of which the one or other can be cut out
of circuit, and if furthermore the strength of the field be rendered capable of
having its action varied between the limits of x and 2 x either by the introduction
of resistances or by cutting out part thereof, then there may be obtained up to &
fourfold variation of speed, as compared with the regulation by change in the
armature winding, or in the strength of the field magnet alone.
The connections possible with this arrangement lie between the two limits.
(1) Both armature windings connected in parallel with half the field magnet
power.
(2) Both armature windings in series with full field magnet power.
The possibility, obtained by this means of connection, of driving shunt wound.
motors with very considerable variation of speed produces the new technical effect,
that the arrangement of toothed gearing heretofore employed may be entirely
dispensed with so that the attendant can, with the sole use of a suitable switch
obtain any desired speed.
This object could not be obtained with the electro motors having their con-
nections arranged as heretofore for varying the speed, because it is necessary with
this that the motor should maintain the speed that has once been chosen
independently of the load.
For carrying out the above described method of operating in a simple and
reliable manner the following construction is employed which renders it impossible
that a change in the connections can be made during the running of the motor,

page_text: whereby short circuiting of the motor may be produced.
In this arrange-
ment four speeds of the motor are assumed possible, namely 3200, 2400, 1600
and 800 and the accompanying drawing shews a diagram of the connections for
3200 revolutions.
The current coming from the generator circuit passes to the pivot of lever H
which, in the state of rest lies upon the insulating piece i. If the lever be moved
to the right, it will come consecutively in contact with the contact pieces.kand
bar 8, whereby the electro-magnet will be excited to a gradually increasing
degree. (The current passes from through the magnet winding E' E
resistances to 20³, contact c arm a to segment II, then through spring 4 back
to the negative terminal of the supply circuit.) On the further motion to the
right, the lever H comes in contact with the contact piece c'. The current will
then also pass through the armature winding from the + terminal through H, c',
through the resistances W' W', spring 1, into segment 1. Here the current
divides into two parts; the one part passes through spring 2 to the armature A¹
and spring 5; the other through spring 3, armature A* and spring to segment II,
whence it will pass, together with the other part current through spring 4 to the
terminal of the supply circuit.
-
In proportion to the increase of speed of the motor in starting the resistance W
is decreased until the lever comes upon contact c. The motor now works with
3,200 revolutions. If it is desired to work with, for instance, 2,400 revolutions,
corresponding to the next lower step of the working machine, the disc S is turned
until arm a lies upon contact c³.
A portion of the resistance w¹ w' is now cut out of the shunt circuit, so that the
magnetic field is strengthened.
The exact positions of the ring S for the particular number of revolutions
required are insured by a spring catch f taking into notches thereon.
For passing from 2,400 revolutions to 1600 or 800, the lever H requires to be
turned completely to the left, and the motor is consequently entirely cut out of
circuit. The finger d fixed on the lever H now presses against the locking bolt b
and raises it out of the notch n¹ of disc S. The latter can now be turned until a
rests upon c6 or c 7, according as the motor is to make 1600 or 800 revolutions.
At the same time springs 3 and 5 are thereby brought in contact with
segment III while springs 1 and 2 remain in contact with segment I and springs 4
and 6 with segment II. On again putting the motor in circuit, that is to say, on
moving lever H to the right, the current passes from H through c³, spring 1,
segment I, spring 2 to the armature A 1; from here through spring 5, segment III,
spring 3 to armature A 2, and then through spring 6 segment II spring 4 back to
the terminal of the supply circuit.
The two windings are now connected in series.
By causing a to lie upon c6 or c 7, w 1 is either put in or out of circuit and the
magnetic field strengthened.
The resistance serves for regulating the strength of the magnetic field for
speeds lying between those above indicated.
In the above described construction, the lever H with the contacts i, c1, c2, c 3,
k1, 2, and s, as also the resistances W₁ and W³, serve for starting the motor
while the disc S with the segments I II III contacts c4, c5, c6 and c 7, as also
the resistances to 1 and w 2 serve for varying the speed of the motor.
Instead of connecting the two armature windings in parallel, only one thereof
may be used and the other be entirely cut out, and generally, the connecting and
contact devices may be variously modified from the arrangements shewn.
Dated this 20th day of November 1893.
ABEL & IMRAY,
Agents for the Applicant.

page_text: Regulating Apparatus for Electro Motors.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery
Lane, in the County of London, Consulting Engineer and Chartered 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 :-
For the purpose of regulating the speed of electro motors it has been customary
hitherto either to divide the armature winding and, according to requirements, to
connect the separate parts either in parallel, or in series, or the windings of the
field magnets have had their exciting action varied by the interposition of
resistances. Both methods of regulating suffer from the defect that with the
alteration of the connections there always occurs an alteration in the position of
the neutral axis, causing the brushes to produce sparking and requiring them to be
shifted in accordance with the changed position of the neutral axis.
The present invention relates to a method of connecting electro motors wherein
this disadvantage is obviated by simultaneously so altering the connections of the
armature winding and the strength of the field magnet winding that the position
of the neutral axis remains unaltered, and that consequently no shifting of the
brushes after each regulation of the speed is required.
In addition, by the alteration of the connections of the armature winding jointly
with that of the field magnet winding the advantage of a greater range for the
variation of the speed is obtained.
If for example, the armature winding be divided into two parts which can either
be connected in parallel or in series, or of which the one or other can be cut out of
circuit, and if furthermore the strength of the field be rendered capable of having
its action varied between the limits of and 2 either by the introduction of
resistances or by cutting out part thereof, then there may be obtained up to a
fourfold variation of speed, as compared with the regulation by change in the
armature winding, or in the strength of the field magnet alone.
The connections possible with this arrangement lie between the two limits.
(1) Both armature windings connected in parallel with half of the field magnet
power.
(2) Both armature windings in series with full field magnet power.
The possibility, obtained by this means of connection, of driving shunt wound
motors with very considerable variation of speed produces the new technical effect,
that the arrangement of toothed gearing heretofore employed may be entirely
dispensed with so that the attendant can, with the sole use of a suitable switch
obtain any desired speed.
This object could not be obtained with the electro motors having their connections
arranged as heretofore, for varying the speed, because it is necessary with this that
the motor should maintain the speed that has once been chosen independently of
the load.
For carrying out the above described method of operating in a simple and
reliable manner the following construction is employed which renders it impossible
that a change in the connections can be made during the running of the motor,
whereby short circuiting of the motor may be produced. In this arrangement four
speeds of the motor are assumed possible, namely 3200, 2400, 1600 and 800 and
the drawing accompanying my Provisional Specification shews a diagram of the
connections for 3200 revolutions.
The current coming from the generator circuit passes to the pivot of lever H
which, in the state of rest lies upon the insulating piece i. If the lever be moved

page_text: to the right, it will come consecutively in contact with the contact pieces k¹ k* and
bar s, whereby the electromagnet will be excited to a gradually increasing degree.
(The current passes from s through the magnet winding E' E' resistances w w0³
contact and a to segment II, then through spring 4 back to the negative terminal
of the supply circuit.) On the further motion to the right, the lever H comes in
contact with the contact piece c¹. The current will then also pass through the
armature winding from the + terminal through H, c', through the resistances W¹ W³,
spring 1, into segment I. Here the current divides into two parts, the one part
passes through spring 2 to the armature A' and spring 5; the other through
spring 3, armature A and spring 6 to segment II, whence it will pass together
with the other part current through spring 4 to the negative terminal of the
supply circuit.
In proportion to the increase of speed of the motor in starting the resistance W
is decreased until the lever comes upon contact c³. The motor now works with
3200 revolutions. If it is desired to work with, for instance, 2400 revolutions,
corresponding to the next lower step of the working machine, the disc S is turned
until arm a lies upon contact c. A portion of the resistance w¹³ is now cut out
of the shunt circuit, so that the magnetic field is strengthened.
The exact positions of the ring S for the particular number of revolutions
required are insured by a spring catch taking into notches thereon.
For passing from 2400 revolutions to 1600 or 800 the lever H requires to be
turned completely to the left, and the motor is consequently entirely cut out of
circuit. The finger d fixed on the lever H now presses against the locking bolt b
and raises it out of the notch n' of disc S. The latter can now be turned until a
rests upon c or c', according as the motor is to make 1600 or 800 revolutions.
At the same time springs 3 and 5 are thereby brought in contact with
segment III while springs 1 and 2 remain in contact with segment I and springs 4
and 6 with segment II. On again putting the motor in circuit, that is to say, on
moving lever H to the right, the current passes from H through e, spring 1,
segment I, spring 2 to the armature A¹; from here through spring 5, segment III,
spring 3 to armature A', and then through spring 6 segment II spring 4 back to
terminal of the supply circuit.
the
-
The two windings are now connected in series. By causing a to lie upon c
or c', w¹ is either put in or out of circuit and the magnetic field strengthened.
The resistance to serves for regulating the strength of the magnetic field for
speeds lying between those above indicated.
In the above described construction, the lever H with the contacts i, c¹, c², c³, k¹, k²,
and s, as also the resistances W₁ and W', serve for starting the motor while the
disc S with the segments I II III contacts c, c, c and c', as also the resistances w¹
and serve for varying the speed of the motor.
Instead of connecting the two armature windings in parallel only one thereof may
be used and the other be entirely cut out, and generally, the connecting and contact
devices may be variously modified from the arrangements shewn.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In regulating apparatus for electro motors with two or more armature circuits
leading to separate current receivers, the method of connecting these as also the
field magnet circuit with a regulating apparatus in such manner, that on altering
the connections of the armature circuits or cutting out part thereof, the strength of
the magnetic field is also altered, for the purpose of preventing sparking at the
current receiver without requiring to change the position of the brushes,
substantially as described.
2. For carrying out the method of regulating referred to in the preceding claim,
a regulating apparatus in which the contact levers or devices serving to start the
motor and for varying the connections of the armature and field magnet circuits

page_text: are so combined with each other that the changing of the said circuit connections
can only be effected when the motor has been put out of circuit by means of the
starting apparatus.
3. A construction of the regulating apparatus referred to in the preceding claims,
wherein the lever H of the starting apparatus, on being moved into position for
cutting the motor out of circuit is caused to disengage a locking bolt b which holds
the disc S while the springs 1 to 6 in connection with the segments I, II, III,
arm a and contacts c¹ to c' serve to vary the connections in the manner, substantially
as herein described.
14th of T..1, 1904
ABEL & IMRAY,
Agents for the Applicant.