Improvements in Electric Circuit Breakers.
Year: 1899

page_text: Improvements in Electric Circuit Breakers.
I, REGINALD BELFIELD, Electrician, 32, Victoria Street, Westminster, in the
County of London, England, do hereby declare the nature of this invention to
be as follows:-
This invention relates to automatic circuit breakers and has for its object to
provide an instrument of this description which shall be operated when the
direction of the current in the line is reversed.
According to this invention an electric motor is provided through which is
passed the line current or a current derived from such line current and chang-
ing in direction when the direction of the line current changes. Such derived
current may for example be furnished from a transformer when the device is
applied to alternating current circuits. The electric motor is designed so that
a reversal of the current through it causes a reversal in the direction of movement
of the rotary portion thereof, said rotary portion having however its motion
limited by means of suitable stops. The actuating solenoid of the circuit
breaker which may be of any suitable type has included in its circuit a switch
connected with the rotary portion of the electric motor aforesaid, and so
arranged that when said rotary portion is in one of its limiting positions the
circuit through the operating coil is made, and in the other limiting position
the circuit through said coil is broken.
The operation of this device is somewhat as follows:-
When the current through the circuit to be protected is flowing in the
normal direction the rotary portion of the motor is rotated to the limiting posi-
tion in which the circuit through the operating coil of the circuit breaker is
broken. When, however, the current in the circuit to be protected reverses in
direction the direction of rotation of the motor is reversed, and consequently
its rotary portion rotates to the other limiting position, which causes the circuit
through the operating coil of the circuit breaker to be made, and the circuit
breaker is thereby caused to open the circuit.
In order to cause the rotary portion of the motor to take up a definite posi-
tion when the circuit through it is interrupted, and to provide for the easy
adjustment of the same so that the main circuit shall be broken when a reversed
current of a predetermined strength passes through, a spring is attached to the
rotary portion, which spring tends to rotate the rotary portion to that limiting
position which it takes up under the action of the current when flowing in the
normal direction. Consequently, in order to cause the circuit breaker to act,
the reversed current which passes through the motor must be sufficiently strong
to rotate the rotary portion against the resistance of the spring before the
circuit through the operating coil of the circuit breaker can be made. The

page_text: minimum current required to cause the circuit breaker to act can be varied by
adjusting the strength of the spring.
My invention is applicable to circuit breakers for use with direct and with
alternating currents of one or more phases, and in the case of polyphase alter-
nating currents an induction motor of any suitable type may be employed,
such for example as those employed in Watt meters for use with alternating
currents.
Improvements in Electric Circuit Breakers.
I, REGINALD BELFIELD, Electrician, of Westinghouse Building, Norfolk Street,.
Strand, W.C., formally residing at 32, Victoria Street, Westminster, in the
County of London, England, 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 automatic circuit breakers and has for its object to
provide an instrument of this description which shall be operated when the
direction of the current in the line is reversed.
According to my invention I provide an electric motor which is so arranged
that its direction of rotation reverses when the line current is reversed. This
is accomplished by supplying one member of the motor with current which is
constant in direction while the other member of the motor is supplied with
either the line current or with a current which is derived from the line current
or which will reverse in direction when the line current reverses. In the case
of alternating currents one of the members of the motor is supplied with a
current which does not change in phase, which I will call the standard current,
and the other member of the motor is supplied with current which is either
the line current or is derived therefrom and which normally has a particular
phase relationship with the standard current which excites the first-named
inember of the motor. If now the lag of the line current alters by 180° (which
corresponds to a reversal of the current) the direction of rotation of the motor
will be reversed. The motor may be of the ordinary type or an induction motor
may be employed.
The current which is constant in direction or which I call the standard
current may be obtained from a separate source or may be derived from the
bus bars at the generating station.
The rotary part of the motor has its movement limited by suitable stops and
is provided with means whereby in one of its limiting positions it causes the
operating coil of the circuit breaker to become energized or makes the circuit
through the same, thereby breaking the line circuit. This limiting position of
the rotary member of the motor is that which it takes when the line current
reverses in direction or when the lag of the line current is increased or
diminished by approximately 1800. In all other positions of the rotary part
of the motor the operating coil of the circuit breaker is de-energized or the
circuit through such coil is broken so that the circuit breaker does not operate
to open the circuit The current which passes through the operating coil of
the circuit breaker, may be independent of the line current or it may be

page_text: derived therefrom. The circuit breaker may be arranged so that it breaks the
line circuit when a current normally passing through the operative coil is
broken or when the core of such coil becomes de-energized instead of when
such core is energized the precise construction of the circuit breaker being
obviously immaterial in practising my invention.
In the accompanying drawing I have shown, by way of example, one arrange-
ment of apparatus and circuits for carrying my invention into practice.
A is the governing motor through one part B of which is passed the line
current or a current derived from the line current, the current through the
other part of the motor being constant in direction or having a definite phase
which does not change this current I have referred to as the standard current.
The circuit breaker which may be of any suitable type and which is not
shewn in the drawings is provided with an operating coil Cincluded in the
circuit of which is a switch D connected with the rotary portion of the electric
motor aforesaid and so arranged that when said rotary portion is in one of its
limiting positions the circuit through the operating coil C is made, and in the
other limiting position, namely that shown in the drawing where the switch
arm is held against the stop E, the circuit through said operating coil is
broken.
The operation of this arrangement is as follows;
When the current through the circuit to be protected is flowing in the
normal direction the rotary portion of the motor is rotated to the limiting
position in which the circuit through the operating coil C of the circuit breaker
is broken, as shown in the drawing.
When however the current in the circuit to be protected reverses in direc-
tion, the direction of rotation of the motor is reversed and consequently the
rotary portion B and with it the switch arm D rotates to the other limiting
position and completes the circuit of the operating coil of the circuit breaker
at the spring contact stops FG and the circuit breaker is thereby caused to
open the circuit.
In order to cause the rotary portion B of the motor to take up a definite
position when the circuit through it is interrupted, and to provide for the easy
adjustment of the same so that the main circuit shall be broken when a reversed
current of a predetermined strength passes through, one end of a spring His
attached to the rotary portion the other end being fixed, which spring tends to
rotate the rotary portion to that limiting position which it takes up under the
action of the current when flowing in the normal direction. Consequently in
order to cause the circuit breaker to act, the reversed current which passes
through the motor must be sufficiently strong to rotate the rotary portion against
the resistance of the spring H before the circuit through the operating coil C
of the circuit breaker can be made. The minimum current required to cause
the circuit breaker to act can be varied by adjusting the strength of the
spring H, by any suitable means, such as the screw clamp I which allows the
effective length of the spring to be varied.
The diagram hereinafter described is more especially illustrative of my inven-
tion as applied to direct current circuits but its application to alternating cur-
rent circuits of one or more phases will be sufficiently clear to those skilled in
the art without further detailed description. Various modifications may be
made in the apparatus and arrangement of circuits without departing from the
Scope of my invention.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to performed, as communicated to
me by my foreign correspondent, I declare that what I claim is:-
―
1. For breaking a circuit a device comprising a circuit breaker and a govern-
ing motor the rotary portion of which when the current in the circuit reverses or
when the phase thereof changes through 180°, takes up a limiting position in

page_text: which it causes such an operation of the circuit breaker as will break the circuit
to be protected, substantially as described.
2. An electric motor one portion of which is supplied with a current which
does not change in direction or in phase and the movement of the rotary
member of which is limited by stops so that it takes up 'one or other of its
limiting positions according to the direction or phase of the current passing
through its second portion, and with or without a spring tending to cause the
rotary member to normally assume one of its limiting positions, substantially
as and for the purpose specified.
3. The arrangement of a circuit breaker in combination with a governing
electric motor as described and shewn in the accompanying drawing for the
purpose specified.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.