Improvements in Apparatus for Starting Electric Motors.
Year: 1895

page_text: Date of Application, 12th Mar., 1895
Complete Specification Left, 9th Dec., 1895-Accepted, 18th Jan., 1896
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Starting Electric Motors.
We, HENRY WILLOCK RAVENSHAW, of Woodfield Works, Woodfield Road,
Harrow Road, in the County of Middlesex, Electrician, and the corporate body,
trading as EASTON, ANDERSON AND 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 electro-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.
"
To carry this invention into effect, we place in the circuit through the motor,
resistances, preferably arranged in series, part of which may be thrown out of
circuit to start the motor by an ordinary hand-switch, operated by the attendant or
by any other mechanical starting appliances. We leave however certain "safety
resistances, not controlled by the attendant or mechanical starting switch, still
remaining in the circuit through the motor, so that, at starting, the current so
admitted to the motor, is only of such amount as will do no injury to the coils and
circuits of the motor, should it not be able to start; and yet is sufficient to start
the motor, if not overloaded, without dangerous shock upon the work transmitting
gear.
The subsequent removal of the said "safety" resistances is automatically effected,
after the motor has started, and is running at a fair speed, by the action of a
solenoid and switch arranged as follows:-
We place a solenoid coil as a shunt circuit between the terminals or brushes of
the motor. When the motor is at rest, and there is no internal reaction from the
motor, but a small current will pass through the solenoid, the core of which is
maintained in its normal position by a counterbalancing weight or spring. A
sliding switch attached to, and operated by, the said core, under these circumstances,
leaves the "safety "resistances included in the main circuit.
As the motor starts and increases its speed, the shunt current through the
solenoid increases, and gradually draws in the core, operating the sliding switch
gradually, so as to withdraw the "safety" resistances one by one from the main
circuit through the motor.
"
The starting and "safety resistances may be arranged on separate switch
boards, or on the same, and a reversing switch may be used with the motor in any
known manner.
An advantage arising from this method of safety starting apparatus, is that the
automatic solenoid and safety switch and resistances, may be placed at a considerable
distance from the motor, and a mutor so fitted with easy starting apparatus is
conveniently adapted to work lifts, hoists, hauling machinery or other work, where
the inertia to first movement may be excessive.
Dated this 10th day of March 1805
FELL & WILDING,
1, Queen Victoria Street London, E.C. Agents for the Applicants.

page_text: We, HENRY WILLOCK RAVENSHAW, late of Woodfield Works, Woodfield Road,
Harrow Road, in the County of Middlesex, but now of 110 Cannon Street,
London, E:C., 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 electro 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 reference to the drawings hereto. annexed and to the letters
and figures marked thereon.
. Figure 1 is a diagrammatic view of the complete apparatus.
Figure 2 is a diagrammatic view of the same with some slight modification of the
-resistances.
To carry this invention into effect we place in the circuit A A of the electric
motor B of any convenient type, resistances C C', preferably arranged in series
where metallic, but these resistances may be of any suitable material or fluid, part
of which C may be thrown out of circuit to start the motor by an ordinary hand
switch D, operated by the attendant or by any other mechanical starting
appliances.
These hand-operated starting resistances are not always necessary, we therefore
show in Figure 2 a hand starting switch D without such resistances included at
that part of the circuit.
In: all cases however we place certain safety resistances C' in the circuit of the
motor B which are not controllable by the attendant or by the mechanical starting
switch, but which still remain in the circuit at the moment of starting, so that the
current so admitted to the motor when at rest is only of such amount as will do no
injury to the coils and circuits of the motor, should it not be able to start, and yet
is sufficient to start the motor if not overloaded, without dangerous shock upon the
work transmitting gear.
The subsequent removal of the said safety resistances is automatically effected
· after the motor has started and is running at a fair speed, by the action of a
solenoid E and sliding switch F arranged as follows:-
.
We place a solenoid coil E as a shunt circuit between the terminals of brushes G
of the motor A. When the motor is at rest and there is no internal re-action from
the motor only a small current will pass through the solenoid coil E, and its core H
is unaffected and is maintained in its normal position by a spring K or an equivalent
counterbalance weight. A sliding switch Fattached to and operated by the said
core H, under these circumstances, leaves the safety resistances C' included in the
main. circuit.
As the motor starts and increases its speed, the shunt current through the solenoid
coil E increases and gradually draws in the core H operating the sliding switch F,
so as to withdraw the safety resistances C¹ one by one from the main circuit through
the motor. On stopping the motor, or should the motor be arrested by excessive
work, the said safety resistances are automatically again thrown into the circuit.
The starting and safety resistances may be arranged on separate switch boards

page_text: as shown, or on the same, and a reversing switch may be used with the motor in
any known manner.
It is obvious, that the resistances CC may equivalently be made of any suitable
material or fluid, or in the case of alternating circuits may be equivalently
represented by what is well known as a choking coil of which the operation and
effect would be the same as hereinabove described.
An advantage arising from this method of safety starting apparatus, is that the
automatic solenoid safety switch and resistances may be placed at a considerable
distance from the motor, and a motor so fitted with easy starting apparatus is
conveniently adapted to work lifts, hoists, hauling machinery or other work, 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 or equivalent choking devices in the main circuit traversing said motor
thrown out or in on starting or stopping automatically in whole or in part by au
electrical device operated by an electric shunt current between the terminals or
brushes of the motor, substantially as described.
2nd. In an apparatus for starting electric motors, the combination with the motor
of a solenoid or equivalent electrical device adapted to be operated by a shunt
circuit from terminals or brushes of said motor, and a sliding switch traversing a
series of resistances in the circuit traversing said motor, to remove the same
automatically and gradually from the said circuit 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 therein, a shunt circuit from terminals or brushes of
motors traversing a solenoid or equivalent electric device, a series of further
resistances in main circuit of motor taken out by action of said solenoid after first
starting the motor, substantially as described.
4th. Apparatus for starting electric motors, substantially as described and illustrated
berewith.
ليم
1
100
FELL & WILDING,
1 Queen Victoria Street, London, E.C., Agents for the Applicants.