Improvements relating to the Regulation of Electric Motors.
Year: 1895

page_text: Date of Application, 11th Feb., 1895
Complete Specification Left, 25th July, 1895-Accepted, 9th Nov, 1895
[Communicated from abroad by EMILE LAUHOFFER, Engineer, ARTHUR
BURGHARDT, Constructor, and JACQUES BURGHARDT. Constructor, all of
Mulhausen, in the Province of Alsace and Empire of Germany.]
Improvements relating to the Regulation of Electric Motors.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 31, High Holborn, in the County of Middlesex,
6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the
County of Lancaster, and Lower Temple Street, Birmingham, in the County of
Warwick, Civil Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention has for its object to regulate the distribution of current in an
electrical installation in such a manner as to enable the motors connected there-
with to be driven at any desired speed without loss of efficiency.
For this purpose we utilise the effect which the strength of the inagnetic field of
a motor has upon its speed in combination with a plurality of circuits having
currents supplied to then at different potentials. The armature of a motor can
be switched in one or other of these circuits by means of a regulating apparatus.
Our invention consists essentially in the provision of means whereby the
switching of the motors from one circuit to another is always accompanied by an
alteration in the intensity of the magnetic field so that no alteration in the speed
occurs, because the alteration of the potential is counteracted by that of the
simultaneously altered intensity of field.
By regulating the field strength it is possible to obtain all intermediate speeds
between the number of revolutions effected by the separate currents of different
potentials, and thereby to secure a continuously alterable number of revolutions of
the motor.
Improvements relating to the Regulation of El
CENT
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency of
Foreign Patent Solicitors, 31, High Holborn, in the County of Middlesex,
6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the
County of Lancaster, and Lower Temple Street, Birminghamn, in the County of
Warwick, Civil 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 :-
The present application has reference to a new method of regulation designed to
secure in an electric power installation a continuous, (that is to say not jerky)
alteration of the number of revolutions of the motors and to so arrange the

page_text: conducting and regulation of the current that the apparatus can always work with
the maximum efficiency and the single motors can be made of the minimum size
for a given maximum power. In order to effect this there is arranged firstly, a
system of mains the potentials of which are approximately as the terms of a
geometrical progression and secondly a regulating apparatus which effects 5
automatically the changing of the motors to the separate circuits as well as the
simultaneously effected alterations of the field intensity of the motors.
The following more fully explains the principle of this invention :-
In this explanation E indicates the potential of the current flowing to the motor,
A indicates a constant depending upon the motor, n represents the number of
revolutions of the motor in general, a the ratio of the maximal and minimal
number of revolutions which with equal potential can be obtained solely by
alteration of the magnetic intensity of the motor.
The smallest number of revolutions which can be obtained without altering the
potential E is n =
is n₁ = A. E.
A. E
a
the largest number of revolutions on the other han
The number of revolutions n₁ can however also be obtained by use of the
potentials a. E because this
1
A. a. E
N₁ =
= A. E
a
na
= A. a. E
Moreover this number of revolutions n₂ can also be obtained by calculation of
the potential
in which case
n₂ =
a². E
A. a². E
= A. a. E and
a
and so on.
no
nz A. a². E.
and n₁, n₁ and no, n₂ and ng
1
Between
and so forth the number of revolutions
can be altered in as small a degree as desired by suitable division of the
regulating mechanism of the magnets so that any number of revolutions lying
between these limits can be obtained. Moreover it is possible by successive
application of the potentials E, a. E, a² E, a³ E.. a E any number of
revolutions lying between no and N + 1.
n
It is however possible to arrange a simplification of the potential system in the
following manner. If in such a case we take
The potential E can be chosen of any size according as it is desired to work.
with higher or lower potentials.
The quotient a depends upon the construction of the motor. In order however
to conform to these conditions the source of current must be constructed as
follows:-
-
The armature of the generating dynamo must be wound with several turns
inserted in series, the number stand to one another in the proportion of the
members of the above geometrical ratio in such a manner that between every two
of these current circuits a derivation of current can take place. By means of this

page_text: division of the potential of the current conducted to the motors is secured that for
a given torsion to be effected by the motor, the regulation of the number of turns
between two numbers of revolutions determined by potentials in series requires for
the total potential intervals the same total alteration of the field intensity and
the strength of the armature current, whereby the dimensions of the motor are
limited to a minimum.
Figure 1 of the accompanying drawings displays the principle of this
arrangement. The dynamo E acts at the same time as exciter and as primary
machine. The same develops at its terminals the potential E which is kept
higher or lower according to the size of the apparatus and by means of which the
losses of potential can be equalised.
The circles denoted by e, a. e, a² e & ae represent the windings of the primary
machine. The shunts I. V indicate the respective connection of the motor for
obtaining the alteration of the potentials between the limits no to n..
The strength of the current round the field magnets of the motor is regulated
by means of the regulating apparatus R. W. In order to undertake the specified
regulation it is necessary to have a regulating apparatus which is illustrated in the
accompanying drawing as follows :—
The Figures 2 and 2 represent a plan of the regulating apparatus in combination
with the primary machine.
Figure 3 shows the apparatus in lengthwise section.
Figure 4 shows a cross section of Figure 3 from a to b.
Figure 5 shows a similar section on cd the ring plate 33 and 16 having been
taken off.
In Figures 6 and 7 a cross section of Figure 3 on the line c d is shown whereby
the plate 33 is also shown.
In Figures 8 and 9 the lengthwise section and the plan view of a special
arrangement of Figure 3 is shown. The construction of the arrangement
according to Figures 2,7 is as follows:-
In the frame 1 is secured a fixed shaft 2 on whose upper end a movable sleeve 3
is placed the outer end of which has a square 4. This piece 3 carries an arm 5
acting as a sliding contact which slides on the one side upon the contact ring 6
and upon the other side upon the segment 7 arranged more or less in the form of
a circle. The lower end of the piece 3 is provided with a spur wheel 8. By
means of the spur wheels 10 upon the shaft 9 the second sleeve 12 fixed upon the
lower part of the shaft 2 with its spur wheel 11 is caused to revolve. The said
sleeve is firmly attached to a circular plate 13 carrying a changing device
described below. Upon the sleeve 12 is placed loosely a double arm 14 bearing a
sliding contact 15. The latter slides on the one side upon the contact ring 16 and
on the other side upon the circularly arranged segmental shaped pieces 17 E,
18 a E, 192E, 20 a³ E, 21 a¹ E, and 22 (Fig. 5).
The contact ring 16 is provided with two short-circuit bars 23, 24 upon which
is a sliding contact 25 fixed on the plate 13. Upon the circular shaped plate 13
are two swinging attachments, 26, 27 controlled by springs which attachments when
moved against each other lie close to the supporting bolt 28. The arm 14 carries
at its end a roller 29 which presses against the swinging attachments alternately
according as a right or left turn of the arm is in progress. The second end of the
arm 14 is provided with a projection 30 in the interior of which there adjusts itself
radially a bolt provided with spring pressure the outer end of which is divided
into two parts 31, 32 each of which is opposed to the other (is sloped off as shown
in Figures 3, 5, 6 and 7). Above the circular plate 13 there is placed in the
frame a fixed ring plate 33 which is provided on its upper side with projections 34
and on its under side with projections 35. These projections whose inner
projecting end is formed in the shape of an inclined plane actuating the bolts 31, 32
and thereby the arm 14 alternately according as a left turn or right turn of the
arm 13 is in progress, in such a manner that the latter during the turning of the
disc 13 is held fixed for a certain time and thereby the spring arm 26 or 27 is

page_text: moved. The circular disc 13 moreover carries upon 2 bolts 36 a bar 37 shaped in
such a manner that the bolts 31, 32 with their outwardly projecting heads 38 will
be on further turning of the plate 13 pushed towards the inside and liberated from
the other projections 34 and 35, so that the arm impelled by the compressed spring
of the projection 26 or 27 springs back into the middle position.
In Figure 7 the releasing angle of the arm 14 is indicated by c.
In the frame 1 are moreover the resistances 39 standing in connection with the
contact pieces 7 and necessary for the alteration of the intensity of the field magnets
of the motor and there are also arranged the resistances 40 connected with segmental
pieces represented in Figure 5. The latter are classified in three divisions: The
segmental piece 22 is connected with the short-circuited resistance the segment 17
with a connecting resistance, the segmental pieces E and 18 a E and 19 and so
forth with the transitional resistance. The arrangement of the toothed wheel
gearing in this apparatus is such that whilst the arm 5 is completing a given turn,
the arm 14 passes from one contact E to the other. The construction of the
apparatus according to Figures 8 and 9 is as follows:-
In the frame 1 is also placed a fixed axle 2 upon which the spur wheel 8 is
placed whose upper axle shaft is provided with a square 4. Upon the said axle
shaft is placed a spur wheel 41 which by means of the gears 42 actuates the spur
wheel 43 loosely revolving upon the shaft. Upon the hub of the spur wheel 43
there revolves loosely a disc 44 bearing insulated upon its upper side the segmental
pieces and short-circuit bars as shewn in Figures 24 and 5, as far as the segmental
pieces 17 18, 19, 20, 21 of the connecting resistance. The under side of this disc
has a projection 45 which works between two spring bolts 46 (Figure 9) the
turning of this disc can therefore only take place as far as the bolts 46 permit.
With the hub of the wheel 43 the arm 14 shown in Figure 3 is firmly connected
which also possesses a sliding contact 15; the same arm moreover carries the sliding
contact 25 working upon the short circuit bars 23, 24, the two short circuit bars
being also fixed upon the disc 44.
The latter bears moreover several arms 47 each of which is provided with the
upwardly projecting piece 48.
Near each arm 47 there is firmly fixed upon the frame an upwardly projecting
piece 49. The arm 14 bears at its end a vertical adjustable bar 50 controlled by
a spring whose lower end is provided with an arm 51 projecting radially to the
outside which latter bears a guiding roller and is acted upon by the fixed pro-
jections 49. Underneath the mechanism above described there is placed in the
frame the resistance 39 for altering the intensity of the field magnets of the motors
as already explained and shown in Figure 2 and the segment shaped contact
pieces 7 shown in circular form in Figure 3, which in this case are not stationary,
but are connected firmly with a disc 52 attached to the spur wheel and rotating
with it. The sliding contact 5 shown in Figure 3 is firmly fixed in the frame and
in order to secure a uniform pressure of the same against the several contacts 7 it
possesses a spring. The segmental pieces 17 of the conducting resistance shown
in Figures 24 and 5 and serving as contacts are according to this construction not
placed upon the disc 44, but upon the periphery of a cylinder 53 rotating around
the fixed shaft 2 which connects thereto the toothed wheel 54 and gears 55 with
the wheel 8. The place of the arm 15 serving as a sliding contact as shown in
Figure 3 is taken in this case by a sliding contact 56 fixed firmly in the frame 1
and standing under pressure of a spring. The segmental pieces 17 serving as
contacts are moreover connected with a contact ring 57 which takes the place of
the contact ring 16 shown in Figure 3, this contact ring is of course in permanent
connection with a further sliding contact 58. The rotating cylinder 53 carrie-
moreover the requisite resistance 40. The mode of action of this new electrical
driving mechanism and the apparatus in connection therewith is apparent from the
following:-
Let us assume that the apparatus is on open circuit, the arm 5 (Figure 2)
touching a contact point 7, the arm 14 in the position 14" and the arm 25 in the

page_text: position 25ª Figure 2ª. The armature of the motor is short circuited through
the resistance W. The short circuit position serves to stop the motor rapidly,
the apparatus for the altering of the field magnets (Figure 2) is also short circuited
through the arm 25 so that the magnets of the motor are in the condition of
magnetic excitement. If we now turn the hand-wheel placed upon the square 4
in the direction of the hands of a watch, the arm 14 will be moved in the same
direction and leaves the short circuit segment 22 and proceeds to the contact
piece 17 of the current resistance. Up to this point of time when the arm 14
touches the potential segment E the apparatus for the alteration of the intensity
of the field magnets remains short circuited and consequently out of operation.
As soon as the arm 14 touches the first potential segment the arm 5 reaches the
contact point 7 whilst the arm 25 has connected the short circuit bars 23, 24.
From this moment therefore the apparatus for the regulation of the intensity of
the field magnets commences to operate, the motor is now in connection, and runs
with the number of revolutions no If the hand-wheel be turned further in the
direction of the hands of a watch the arm 5 moves past the resistance contacts 7
in the direction 7ª, 7b, 7° and 7d whereby the number of revolutions of the motor
is increased in consequence of the weakening of the field, but notwithstanding this
remains in the limits n,.-N₁₁ When the arm 5 has reached the position 7° the
arm 14 is at the end of the potential segment E and is held firm in this position in
spite of the further turning of the hand-wheel because the spring bolts 31, 32
according to Figure 3 or the bolts 50 according to Figure 8 will be held fast by
one of the projections 34 or 35 according to Figures 6 and 7 or projection 48
according to Figure 9.
On further turning, the bolts 31, 32 will be released by the bars 37 or the
bolts 50 by one of the projections 49, so that the arm 14 which has been standing in
the fixed position under the pressure of the springs of the projections 26 or 27 or
of the bolts 46 springs back into the normal position and reaches the next
potential segment E in this case a. E. The arm 5 cannot remain standing on the
intervals 7, 7, 78, it can only take a fixed position on the points 7ª, 7d. The
arm 14 springs in a moment from one potential segment to another whilst
the arm 5 moves from the position 7d to the position 7. The number of
revolutions of the motor will in this case after this chauge also be equal to n₁
In this
and can in the limits n₁-n, be altered by further turning of the arm 5.
manner the motor can be caused to work with a greater speed, the momentum
remaining the same. The segmental pieces 18 or 19 or 20 and so on are intended
to reduce the sparking at the moment of change in the event of an overloading of
the motor to a minimum. The sliding contact 15 passes over these contact pieces
and can never remain standing upon the same owing to the influence of the arm 14.
The apparatus works in the event of the turning of the hand-wheel fixed upon the
piece 4 in the opposite direction, as above described, but of course in the opposite
sense, that is to say, in the reducing direction. If the arm 14 arrives in the
position 14 and the arm 25 in the position 25 then the apparatus has reached its
maximum number of revolutions. The arm 5 is turned by the mechanism
correspondingly whilst the arm 14 has passed over so much space as is necessary
in order to pass from one potential segment E to the other and moreover in the
same relative position.
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 an electric regulating apparatus for the purpose of obtaining a con-
tinuously alterable number of revolutions of the motors of an electric power
installation, the application of a system of mains having different potentials which
are approximately as the terms of geometrical progression in combination with
corresponding alterations of the magnetic field of the motors.
2. In electric regulating mechanism as set forth in Claim 1, a circuit changing

page_text: apparatus which compulsorily causes an alteration in the field intensity corre-
sponding to the alteration of the potential so that on changing the circuit an
alteration of the number of revolutions does not occur, the influence of the
alteration of potential being neutralised by the correspondingly resulting opposite
influence of the alteration of the intensity.
3. In apparatus as set forth in Claim 2 the device for changing the intensity of
the field magnets whose contacts are arranged in circular form;
so that
according to the direction of the turn of the arm 5 (or the disc 52) the resistance
is gradually cut in or cut out and correspondingly on further turning is suddenly
cut in or cut out.
4. In apparatus as set forth in Claim No. 2 the circular or straight circuit
changing device so arranged that an alteration of the potential simultaneously and
compulsorily causes the corresponding alteration of the intensity of the field
magnets, whilst also the field can be gradually and independently used for
regulating the number of revolutions.
5. The regulating apparatus for electric motors constructed substantially as
described and with reference to Figures 3 to 7 or 8 and 9 of the accompanying
drawings.
TI
3005
W. P. THOMPSON & Co.,
Agents.