Improvements in Apparatus for Starting Electric Motors.
Year: 1894

page_text: Date of Application, 8th June, 1894
Complete Specification Left, 8th Mar., 1895-Accented, 27th Apr., 1895
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Starting Electric Motors.
We, HENRY WILLOCK RAVENSHAW, of Woodfield Works, Harrow Road, in
the County of Middlesex, Electrician, and the corporate body trading as Messrs.
EASTON ANDERSON & GOOLDEN, LIMITED, of 3 Whitehall Place, in the County
of Middlesex, Engineers, do hereby declare the nature of this invention to be as
follows:-
This invention relates to apparatus for the easy starting of electric motors to
prevent abrupt shock upon either the driving or driven mechanism, and at the same
time to prevent injury to the coils of the motor or circuits connected therewith,
which might be caused by the sudden flow of a powerful electric current before the
motor has started or before it is running at a fair speed.
The apparatus employed is as follows:-In the main circuit to the motor is
placed in series a number of resistances preferably divided in two groups and
connected to two distinct switch-boards of usual construction, which control the
throwing in or out of the said resistances in the said circuit. A switch of the
usual construction for the reversal of the current to the motor may also be employed
in addition, by which the rotation of the motor may be reversed at will by an
attendant.
When it is desired to start the motor, the attendant operates by suitable
mechanism the switch of one of the switch boards aforesaid, by which a portion
only of the resistances in the supply circuit are taken out.
The current so admitted to the motor is only of such amount as will do no injury
to the coils or circuits of the motor, should it not be able to start, and also effects
the starting, if the resistance is not too great, without dangerous shock upon the
work transmitting gear.
Upon the shaft of the notor, or connected in any way to the rotating portion of
the notor, is centrifugal apparatus, such as any ordinary engine governor, which
operates against a spring or weight reaction, so soon as the motor begins to
revolve.
The rectilinear movement, resulting from the centrifugal action of the said
apparatus or governor, is utilized to operate the switch of the second switch board
to throw out further resistances from the supply circuit, and thus to afford
automatically a greater supply of current to the motor after it is already in
motion.
Equivalently, all the resistances may be controlled by a single switch operated
for a part of its travel by the action of the attendant and for the remainder of its
travel automatically by the centrifugal apparatus or governor.
An electric motor fitted with such easy starting apparatus is conveniently adapted
to work lifts or hoists, hauling machinery, or other work, where the inertia to first
movement may be excessive.
Doted this 8th day of June 1894
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicants.

page_text: Improvements in Apparatus for Starting Electric Motors.
We, HENRY WILLOCK RAVENSHAW, of. Woodfield Works, Harrow Road, in
the County of Middlesex, Electrician, and the corporate body trading as EASTON
ANDERSON & GOOLDEN LIMITED, of 3 Whitehall Place, in the County of
Middlesex 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 :-
This invention relates to apparatus for the easy starting of electric motors, to
prevent abrupt shock upon either the driving or driven mechanism, and at the same
time to prevent injury to the coils of the motor or circuits connected therewith,
which might be caused by the sudden flow of a powerful electric current before the
motor has started, or before it is running at a fair speed.
And in order that this invention may be the better understood we now proceed to
describe the same in relation to the drawings hereto annexed reference being had
to the figures and letters marked thereon. Like letters refer to similar parts in the
various figures.
Figure 1 is a diagrammatic view of the complete apparatus.
Figure 2 is a diagrammatic view of the same, with slight modification of
resistances.
A is the electric motor of any convenient and known construction, and B. B.
represent the main circuit through the said motor.
C. C. are a number of resistances introduced into the main circuit, conveniently
in series, and divided in Figure 1 into two groups, and limited in Figure 2 to one
group.
These resistances have the usual contacts arranged upon switch boards, S. S.
which may be distinct or together; one group of resistances being controlled by
the usual hand switch D, operated by the attendant or mechanically, and the other
being controlled automatically by the machine, by a. sliding switch E, as hereinafter
more fully described.
A switch of the usual construction for the reversal of the current to the motor,
not shown in drawing, (as it is a well known appliance, as applied to the commutator
of the motor), may also be employed, by which the rotation of the motor may be
reversed at will by the attendant.
Upon the shaft F of the motor A, or connected to the rotating portion of the
motor, is a centrifugal apparatus, such as an ordinary engine governor G, which
operates by centrifugal action against the reaction of a spring or weight, as soon as
the motor begins to revolve.
The rectilinear motion resulting from the centrifugal action of the said apparatus,
or of the governor G, is communicated by a rocking lever H or other equivalent
connection to the sliding switch E on a switch board with resistances thereon, and
thus automatically operates the switch E, to throw out, one or more of the said
resistances, as the acceleration of the motor takes place.
When it is desired to start the motor the circuit is closed by the attendant or by
mechanical means by the operation of the band switch D. and where there are a
group of resistances on this switch board, part or all of these resistances can be
thrown out to start the motor, the resistances of the governor-controlled switch-
board still remaining in circuit.
The current so admitted to the motor is only of such amount as will do no injury
to the coils or circuits of the motor, should it not be able to start; and also the
start is effected (if the load be not too great) without dangerous shock upon the
work transmitting gear. The arrangement in Figure 1 with a group of resistances
on hand-starting lever switch-board, still further enables the attendant to graduate

page_text: the shock of starting, but I find that in many cases the resistances on the starting
switch-board are not necessary.
When the motor has once started, the centrifugal action of the governor G or
equivalent centrifugal apparatus, operates automatically the sliding switch E,
removing further resistances from the circuit, and thus affording a greater supply
of current to the motor, after it is already in motion.
Equivalently, the two switch-boards SS may be combined in one board, and may
be controlled by a single switch, operated for part of its travel by the action of the
attendant or mechanically, and for the remainder of its travel automatically by the
centrifugal apparatus or governor.
Although the action of a mechanical centrifugal governor may be known in
conjunction with an electric motor, for the purpose of automatically throwing
resistances in and out of the main circuit, to control the speed of the said motor,
in this invention the action of the centrifugal apparatus or governor is quite
distinct, and in a reverse sense to the operation of a speed governor. The
automatic removal of resistances from the circuit is here effected as a consequence
of the speed of rotation, and they are fully cut out, when full speed is obtained.
Similarly the re-insertion of the resistances only occurs, when the motor is being
stopped, and are thus present in the circuit to prevent damage from a sudden
recommencement of the current in either direction.
An electric motor fitted with such easy starting apparatus is conveniently adapted
to work lifts or hoists, hauling machinery, or other mechanism, where the inertia to
first movement may be excessive.
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 :--
1st. An improved apparatus for starting electric motors, consisting of a series of
resistances in the main circuit traversing said motor, thrown out or in on starting or
stopping automatically, in part or wholly, by the action of a device, operated
centrifugally by the rotation of the shaft or other revolving part, of said motor,
substantially as described.
2nd. In an apparatus for starting electric motors, the combination with the shaft
or other rotating part of said motor, of an engine governor, or equivalent device,
operated centrifugally by the rotation of said motor, and a sliding switch operated
by the rectilinear motion of said governor, or centrifugal device, to take out
automatically resistances from circuit, traversing said motor, after first starting the
motor, substantially as described.
3rd. In an apparatus for starting electric motors, the combination with the
circuit traversing said motor, of a starting switch, making and breaking said circuit,
and controlling certain resistances in said circuit; a centrifugal device or governor,
operated by rotation of said motor; and a sliding switch, automatically taking out,
by the action of said centrifugal device, other resistances, in said circuit of motor,
after first starting the motor, substantially as described.
4th. Apparatus for starting electric motors, substantially as described and
illustrated herewith in Figures 1 and 2.
·נים
1002
FELL & WILDING.
1, Queen Victoria Street, London, E.C., Agents for the Applicants.