Improvements in Magnetic Cut Out Apparatus.
Year: 1897

page_text: Date of Application, 16th Nov., 1897
Complete Specification Left, 15th Sept., 1898-Accepted, 16th Nov., 1898
PROVISIONAL SPECIFICATION.
Improvements in Magnetic Cut Out Apparatus.
I, LEONARD ANDREWS, of 20, South Terrace, Hastings, in the County of Sussex,
Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention has reference to improved constructions of magnetic cut out
apparatus of the kind comprising a switch or cut out device proper adapted to
make and break connection in a main or outgoing lead, an electro magnetic device
having a series coil or coils adapted to be arranged in the said main or outgoing
lead, a shunt-coil or coils adapted to be connected across the main and return.leads,
and a magnetic core or cores, and operating mechanism arranged between the core
or cores and the switch or cut out, the series and shunt coils being so proportioned
and arranged that a forward magnetic pull will be exerted in one direction upon
the core or cores with a current supplied from the generating station, and a back-
ward magnetic pull with a current supplied in the reverse direction so that the
core or cores will not act to open the circuit so long as current below at or above
the normal amount is being supplied in a forward direction from the generating
station, nor when the supply of current is cut off, but will act to open the switch
or cut out device in the event of current being supplied in the reverse direction.
In such return current cut out apparatus according to this invention, one of the
windings is wound around a core mounted to turn about a centre and is so disposed
in relation to the other winding and the core as to constitute in effect a shunt
motor that will turn or tend to turn in one direction for a direct current and in
the reverse direction for a return current. The movable core is mechanically
connected to a catch device for releasing a weight or spring which is arranged to
operate a switch or cut out device adapted to make and break the circuit to which
it is applied. The two windings are so arranged relatively to each other that
their combined influence upon the iron core tends to move it in one direction, with
a forward current and in the reverse direction with a return current. When the
current in the circuit is flowing in its normal direction, the movement of the core
tends to securely lock the catch in position but when the series current is reversed
relatively to the current in the shunt winding then the movement of the core tends
to release the catch and open the switch or cut out. The shunt coil is on the
movable core and the series coil is on a fixed bent iron core between the ends of
which the movable core is arranged so as normally to be at right angles, or
approximately so, to a line connecting the two ends.
I apply my invention to alternate current working by making the apparatus
according to the principles well understood, by which, although the currents
are alternating, the simultaneous directions of the currents act relatively as
described with reference to direct currents.

page_text: Improvements in Magnetic Cut Out Apparatus.
I, LEONARD ANDREWS, of 20, South Terrace, Hastings, in the County of Sussex,
Electrical Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
--
This invention has reference to an improved construction of magnetic cut-
out apparatus designed for use with alternating current circuits and of the kind
comprising a switch or cut out device proper adapted to make and break con-
nection in a main or outgoing lead, an eléctro-magnetic device having a series
coil or coils adapted to be arranged in the said main or outgoing lead, a shunt-
coil or coils adapted to be connected across the main and return leads, and a
magnetic core or cores, and operating mechanism arranged between the core or
cores and the switch or cut out, the series and shunt coils being so proportioned
and arranged that a forward magnetic pull will be exerted in one direction upon
the core or cores with a current supplied from the electric generators, and a back-
ward magnetic pull with a current supplied in the reverse direction so that the
core or cores will not act to open the circuit so long as current below at or
above the normal amount is being supplied in a forward direction from the
generators, nor when the supply of current is cut off, but will act to open the
switch or cut out device in the event of current being supplied in the reverse
direction.
In such return current cut-out apparatus according to this invention, one of
the windings is wound around a core mounted to turn about a centre and is so
disposed in relation to the other winding and the core as to constitute in effect
a shunt motor that will turn or tend to turn in one direction for a forward current
and in the reverse direction for a return current. The movable core is mechanic-
ally connected to a catch device for releasing a weight or spring which is
arranged to operate a switch or cut out device adapted to make and break the
circuit to which it is applied. The two windings are so arranged relatively to
each other that their combined influence upon the iron core tends to move it
in one direction, with a forward current and in the reverse direction with a
return current.
When the current in the circuit is flowing in its normal direction, the move-
ment of the core tends to securely lock the catch in position, but when the series
current is reversed relatively to the current in the shunt winding, then the move-
ment of the core tends to release the catch and open the switch or cut out.
The accompanying drawing shows diagrammatically, my improved construction
of magnetic cut out apparatus and its application to alternating current circuits
comprising, by way of example, outgoing and return leads 1, 1ª (hereinafter called
bus bars) and alternating current generators 2, 2ª which are connected in parallel
across the said bus bars and supply the same with alternating currents each through
conductors 3, 3" in one of which is a break 3b normally closed by a switch 4
provided with a loaded arm or lever 4ª which, when released, automatically acts
to move the switch in a direction to open the circuit it controls. The magnetic
cut out apparatus, of which only one is shown arranged to control the circuit of
the alternator 2, comprises a field magnet 5 made in the form of a bent iron core
provided with a series winding 6 and between the polar ends of which the rotary
armature core 7 provided with a shunt winding 8 is pivoted with the normal position
of its field approximately at right angles to the field produced by the series wind-
ing, the armature in this position acting through a catch device 4b, formed in the
example shown by the end of the switch arm or lever 4°, to normally hold the

page_text: said arm or lever in the raised position and the switch 4 in the closed position.
This position of the armature is insured when no current is flowing through the
cut-out device, by loading the armature by means of a spring or weight so that
it normally bears against a fixed stop 7".
The winding 6 is arranged in series with the conductor 3" and alternator 2
which the cut-out apparatus is to control. The shunt winding 8 may be con-
nected to the secondary winding 9 of a transformer the primary winding 9ª of
which is connected as a shunt across the bus-bars 1, 1ª to which the alternators 2,2"
are connected. Or the shunt winding 8 may be itself connected directly across
the bus-bars. As will be seen, the direction of the current in the said shunt
winding 8 will pulsate synchronously with the current in the bus-bars 1, 1" and
will be quite independent of the direction of the current in the series winding 6,
whereas the direction of the current in the latter winding relatively to the current
in the bus-bars, will depend upon whether the alternator 2 is acting as a generator
and supplying current to the bus-bars, or is receiving current from the bus-bars
and is acting as a motor. If both alternators 2, 2 are generating current, then
the direction of the current through the whole system at a given moment will
be represented by the arrow heads shown in full lines, and the polarity of the
In this
field magnet poles and armature poles by the letters N and S thereon.
case, the relative direction of the currents in the shunt and series windings is
such as to tend to make the armature rotate in a clockwise direction against a
stop 10 and so to securely lock the switch 4 in the closed position. If, however,
the alternator 2 should fail, it will tend to short circuit the rest of the system
and the current will rush back into it in the direction shown by the dotted arrow
heads whereas the direction of the current in the other circuit will remain un-
changed. In this case the direction of the series current relatively to the shunt
current will be reversed with the result that the armature will rotate in a counter-
clockwise direction and release the weighted switch lever 4" which will immediately
fall and open the switch 4.
The induction of the shunt circuit 8 must be carefully adjusted to produce the
requisite lag in phase of the shunt current, necessary to obtain the greatest torque
between the two magnetic fields at the time when the armature is required to
release the loaded switch.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed I declare that what I
claim is:
The construction and use as set forth of the improved magnetic cut-out apparatus
for alternating current circuits berein before described with reference to and
shown in the drawings annexed for the purposes specified.
Dated this 15th day of Santember 1898