Improvements in Apparatus for Regulating and Controlling Electric Motora.
Year: 1897

page_text: Date of Application, 2nd Dec., 1897
Complete Specification Left, 3rd Oct., 1898-Accepted, 2nd Dec., 1898
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Regulating and Controlling Electric
Motora.
We, LLOYD HIGGINBOTTOи, Alderman of the City of Manchester, of Hyde Rond,
Manchester, Engineer, JOHN HENRY HINDLE, of Hyde, near Manchester,
Engineer, and THOMAS MANNOCK, of Hyde Road, near Manchester, Engineer, do
hereby declare the nature of this invention to be as follows: —
Our invention relates to improved apparatus for controlling and regulating
electric motors and is more particularly applicable to motors which require to be
started, stopped, and reversed under load, such as those which are coupled direct
to elevators and hoists. It is well known that such motors require to be wound
for a high starting torque so that they will start against the load with a minimum
amount of energy. This is usually accomplished by inducing an abnormally
strong magnetic field in the motor which is gradually reduced as the speed
increases. For this purpose it is generally preferable to use a shunt wound
motor so designed and wound that the shunt winding produces the normal speed,
an additional winding or windings being in series with the armature circuit which
will in conjunction with the shunt winding produce a much lower speed which
may be fixed approximately at from one-half to two-thirds the normal. These
series windings and also any regulating resistances which may be used should be
cut out of circuit gradually and stendily to produce a regular acceleration in the
speed of the motor."
In one form our invention consists of a switch having two parallel
rows of stationary contacts bridged across and connected together by
sliding contacts which in their movement cut out the resistances and afterwards
the series windings of the motor. The sliding contacts are preferably operated
by gravity when starting the motor their movement being controlled by a dash-
not one form of which consists of a piston attached to the sliding contacts and
working in a cylinder containing liquid which as the piston enters the cylinder
is forced through an aperture into another vessel; the aperture is adjustable and
thereby the rate of movement of the sliding contacts may be regulated. A valve
is also provided between the cylinder and the vessel so that the reverse movement
of the sliding contacts may be accelerated if desired.
When used in connection with an elevator the hand rope may be connected
directly to the sliding contacts and the connection may be so made that the move-
ment of the sliding contacts may be limited by the movement given to the hand
rope.
It is also well known that the breaking of the armature circuit of a motor under
load causes a considerable amount of sparking at the point of rupture, such spark
being generally larger and more destructive in proportion to the load on the
motor. The sliding contacts are therefore so arranged that at the moment of
breaking the motor circuit the break occurs simultaneously at a number of places.
For reversing the direction of rotation of the motor we use a revolving double

page_text: pole switch interlocked with the sliding contacts which make and break the
circuit thereby avoiding sparking on the reversing switch when the shunt circuit
is broken.
For the purpose of bringing the motor to rest we employ a pair of soft iron
brake-blocks which may be lined with wood or other substance. The blocks are
drawn by adjustable springs into contact with a brake-wheel and are combined
with electromagnets in such a manner that when the current is switched on to the
motor the electromagnets are excited and draw the bruke-blocks from the brake
wheel.
Improvements in Apparatus for Regulating and Controlling Electric
Motors.
We, LLOYD HIGGINBOTTOM, Alderman of the City of Manchester, Hyde Road,
Manchester, Engineer, JOHN HENRY HINDLE, Hyde, near Manchester, Engineer,
and THOMAS MANNOCK, of Hyde Road, near Manchester, Engineer, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement:-
Our invention relates to improved apparatus for controlling and regulating
electric motors and is more particularly applicable to motors which require to be
started, stopped and reversed under load, such as those which are coupled direct
to elevators and hoists. It is well known that such motors require to be wound
for a high starting torque so that they will start against the load with a minimum
amount of energy. This is usually accomplished by inducing an abnormally
strong magnetic field in the motor which is gradually reduced as the speed
increases. For this purpose it is generally preferable to use a shunt wound
motor so designed and wound that the shunt winding produces the normal speed,
an additional winding or windings being in series with the armature circuit which
will in conjunction with the shunt winding produce a much lower speed which
may be fixed approximately as from one-half to two-thirds the normal. These
series windings and also any regulating resistances which may be used should be
cut out of the armature circuit gradually and steadily so as to avoid sudden
fluctuations in the supply current and to produce a regular acceleration in the
speed of the motor.
In one form our invention consists of a switch having two parallel
rows of stationary contacts bridged across and connected together by
sliding contacts which in their movement cut out the resistances and afterwards
the series windings of the motor. The sliding contacts are preferably operated
by gravity when starting the motor, their movement being controlled by a dash-
pot one form of which consists of a piston attached to the sliding contacts and
working in a cylinder containing liquid, which, as the piston enters the cylinder,
is forced through an aperture into another vessel; the aperture is adjustable and
thereby the rate of movement of the sliding contacts may be regulated. A valve
is also provided between the cylinder and the vessel so that the reverse movement
of the sliding contacts may be accelerated if desired.
When used in connection with an elevator the hand rope may be connected
directly to the sliding contacts and the connection ma be so made that the move-

page_text: ment of the aliding contacts may be limited by the movement given to the nana
rope.
It is also well known that the breaking of the armature circuit of a motor under
load causes a considerable amount of sparking at the point of rupture, such spark
being generally larger and more destructive in proportion to the load on the
motor. The sliding contacts are therefore so arranged that at the moment of
breaking the motor circuit the break occurs simultaneously at a number of places.
For reversing the direction of rotation of the motor we use a revolving double
pole switch interlocked with the sliding contacts which make and break the
circuit thereby avoiding sparking on the reversing switch when the circuit is
broken.
For the purpose of bringing the motor to rest we employ a pair of soft iron
brake-blocks which may be lined with wood or other substance. The blocks are
drawn by adjustable springs into contact with a brake-wheel and are combined
with electromagnets in such a manner that when the current is switched on to the
motor the electromagnets are excited and draw the brake-blocks from the brake
wheel.
Figure 1 shews diagrammatically the apparatus for regulating and controlling
a motor.
Fig. 2 shews one form of the apparatus arranged in connection with a hoist.
Fig. 3 shews the construction of the sliding contact.
Fig. 4 shews the magnetic brake.
Fig. 5 shews a circular form of combined regulating and reversing switch for
hand use for use without dashpot and rope wheel.
Referring to Figures 1 & 2 the apparatus consists of a series of fixed con-
tacts A, B, C, C', 0, &c. connected as shewn to the regulating resistances R and
also to the series windings S of the motor and a series of sliding con-
tacts D, D, D, &c. The sliding contacts as shewn in Figures 1 & 2 descend by
gravity, their rate of descent being controlled by a dash-pot E, consisting of an
inner and outer cylinder containing oil or other liquid F. The sliding contacts
are attached to a piston G which displaces the liquid in the inner cylinder through
a valve H which can be regulated to determine the rate of descent of the piston
and contacts. A relief valve I at the bottom of the inner cylinder allows the
liquid to return freely when the switch is returned to its normal position. It is
advisable when making contact to do so quickly and to obtain direct and reliable
contact us quickly as possible. This we accomplish by allowing the sliding con-
tacts D, D, 13, &c. to descend rapidly at first until they reach the point (J in the
Fig. 1) where they are connected in parallel. This rapid descent is attained by
providing an outlet or outlets K in the inner cylinder of the dashpot E, and by
providing just suflicient liquid in the dashpot to reach to the bottom of these
outlets, so that the piston falls freely until it reaches the liquid expelling the air
through the outlets K and through an aperture L in the cover of the dashpot.
In combination with the arrangement for regulating the motor we arrange a
double pole switch M for reversing the direction of rotation of the motor. This
double pole switch is geared to the hand rope wheel N by means of a quadrant Q
and pinion P. Mounted upon the rope wheel and pinion shaft is a cam wheel T
which in the position_shewn in the drawing holds the arm U which is pivotted
at W against a stop X on the piston rod thus preventing the piston and sliding
contact from descending.
The operation then is as follows:-The rope wheel N being rotated half a
revolution in either direction (according to the desired direction of rotation of the
motor) the switch M is closed, the arm C is released and allows the sliding switch
to descend exciting the shunt coils Y and gradually cutting out the resistances R
and the series windings S out of the armature circuit. According to the arrange-
ment shewn in Figs. 1 & 2 it will be seen that the sliding contacts in descending
provide three parallel paths for the current to flow from one set of stationary
contacts to the other as soon as they reach the point J thus securing greater reliability

page_text: and area of contact. The arrangement shewn also provides that the circuit is
broken first at the contacts A, B, C, &c., and on making the circuit, the reversing
switch is first operated thus obviating any deterioration of the reversing switch
due to sparking. When stopping the motor to enable the sliding switch to be
raised rapidly a relief valve I allows the liquid to enter the dashpot rapidly. In
order to avoid vioious sparking when the circuit is broken by lifting the sliding
contacts to their normal position, we arrange the sliding and stationary contacts
in such a manner that at the moment of breaking the circuit the current passes
in and out of the sliding contacts in series thus dividing the spark into any
desired number of points. This is clearly shewn in Fig. I where assuming the
sliding contacts just leaving the stationary contacts the current passes from (
to D, thence from D to B, thence through D and D' to A, and thence through 1)
and D³ to C¹.
In addition to the above named provision for dealing with the spark when
brecking the circuit the method of connecting shown in Fig. 1 will in itself greatly
obviate sparking. The magnitude or viciousness of the spark is greater in pro-
portion to the excess of the electromotive force or pressure of supply over and above
the back electromotive force of the motor, and if these were equal at any moment
the circuit might then be opened absolutely without spark. When using the
sliding switch aforesaid for breaking the circuit the first upward movement of the
contacts will include the series coils in circuit with the armature, thus increasing
the magnetism of the field magnets of the motor, and owing to the momentum of
the armature and gearing, momentarily generating a sufficiently high back electro-
motive force to allow the circuit to be broken without deterioration of the switch
contacts.
Figure 3 shews a convenient form of sliding contact piece which consists of n
short piece of carbon rod a mounted in a metal tube b which is fixed in a plate c
of non-conducting material, and which contains a spring d which maintains n
permanent and constant pressure between the sliding and stationary contacts.
Figure 4 shews an arrangement (also shewn diagrammatically in Fig. 1) which
we adopt for absorbing the momentum of motor and load and bringing it to
rest. It consists of a pair of magnetic brake blocks 2 which may be lined with
wood or other suitable material 3. These brake blocks are pivotted at 4 and cre
normally held up tightly against the brake wheel 1 by means of an adjustable
spring or springs 5. Suitably arranged electromagnets 6 are fixed behind the
brake blocks 2 and when magnetised overcome the pull of the spring or springs and
pull the brake blocks out of contact with the brake wheel thus releasing it. The
electromagnets 6 may either be wound in series with the armature or magnet
circuits of the motor or they may be extensions of the poles of the motor.
either case the brake wheel would be instantly released when the motor circuit
is completed.
In
Figure 5 illustrates a method of sub-dividing the current at the moment of
breaking in combination with a reversing switch adapted for use as a hand switch,
and dispensing with the dashpot and rope wheel.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that we do not
confine ourselves to the particular details of construction named in the foregoing
specification, and that what we claim is: -
1. The combination of a sliding switch connected with suitable resistances and
series coils, and a liquid dashpot with means for regulating and limiting the
speed of descent, for controlling the speed of the motor and also the rate of
acceleration when starting same substantially as herein described and illustrated.
2. The combination of a sliding switch connected in the manner described and
attached to a dashpot provided with a relief valve so that it may be positively
switched off by the motion of the hand rope without deleteriais sparking by
virtue of the methods of connecting substantially as herein described and
illustrated.

page_text: 3. The combination of a sliding and reversing switch so interlocked that the
circuit is broken by the former leaving the armature series coils and resistances
(connected in series) coupled in parallel with the shunt winding for an appreciable
period, substantially as herein described and illustrated.
4. The combination of a sliding switch with the connections arranged for
gradually accelerating the speed when starting and avoiding sparking when stop-
ping, and suitable brake blocks and electromagnets or polar extensions so as to
ensure synchronous action of the brake arrangement with the switching on or
off of the current by means of the sliding switch aforesaid, substantially as
described and illustrated.
Dated this 2nd day of October 1898.
E. TALBOT,
Agent for Applicants.