US639447A - Polyphase alternating-current magnet. - Google Patents

Description

No. 639,447. Patented Dee. I9, i899.

w. M. scoTT.

POLYPHASE ALTERNATING CURRENT MAGNET.

(Application filed June 11, 1898.)

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UNITED STATES PATENT OFFICE.

VILLIAM M. SCOTT, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO TI-IE CUTTER ELECTRICAL AND MANUFACTURING COMPANY,

NEIV JERSEY.

POLYPHASE ALTERNAT SPECIFICATION forming part of Letters P Application filed June ll, 1898.

Magnets, ot' Which the following is a speciiil,

cation.

My invention relates to improvements in electromagnets, especially with respect to their use with alternating currents.

If to the exciting-coils of the ordinary type of electromagnet employing an armature adapted to beheld to its poles against gravity or spring tension by flow7 of direct or continuous current through the coils I apply an alternating current instead of a continuous current the magnetism will vary as the current varies in passing through points of positive maximum, zero, negative maximum, and zero again practically in unison with the current- Wave. The pull exerted between the armature and pole-pieces will vary with the magnetism. It will then be obvious that during each cycle of the current there are two instants at which the pull is zero. lVhen the magnet is sustaining strain, such as might be imposed by spring force tending to separate the armature from the pole-pieces, such separation will occur at these points of zero pull, and if the current is strong enough as the magnetic pullincreases the armature will be drawn back sharply against the pole-pieces, the frequency of these blows depending upon the frequency of the alternations of the current. For this reason it is obvious that the ordinary electromagnet is unsatisfactory for use with alternating currents.

The object of my invention is to overcome this objection and is accomplished by supplying the exciting-coils With currents,not all (or both) in the same phase, and, further, by providing the core or armature with such projections as will serve to allow the individual magnetic streams set up by each coil to unite and form a resultant stream or streams of uninterrupted flovv Whose continuity is independent of the relative directions ot' thei component streams,

ING-CURRENT MAGNET.

atent N0. 639,447, dated December 19, 1899.

serai No. 633,172, (No maar.)

By the proper Winding of the coils and a proper selection of the phase difference of the exciting-currents the magnetic flux through the armature can be made to approach a constant value.

In the accompanying drawings, Figure l is a diagrammatic view of a magnet With plurality of poles,single armature, and excitingcited by currents not all in the same phase. Fig. 2 is a diagram of electromagnet with direction of magnetomotive forces at a given instant indicated by arrows. Fig. 3 is a side elevation of a portion of an automatic magnetic circuit-breaker employing such a magnet. Fig. 4f is a view in perspective of improved means of securing the armature to the pivoted or flexible supporting member.

In Fig. l, 2 represents a triphase generator, 4C the core, and 5 the armature, and a, h, and c the coils of the electromagnet. The coils are separated from each other by alternative magnetic pathsyl and 7c for the formation of poles upon the cooperation of opposed magnetic streams therthrough-f-that is, the coils tend to cause magnetic streams of different phase, which when they flow in the saine direction unite and iiow in a single stream and when opposed coperatie in forming consequent poles. Thus when magnetic flow in sections a, h, and c is induced in the same direction it will unite to set up a magnetic stream the major portion of which will pass from armature to core, or vice versa at e andf. .Vhile this condition prevails, the members j and 7e could be removed withoutsensibly alter; ing the efficiency of the magnet. Suppose, however, these members being removed, that the magnetomotive force set up by the coil a should be equal to and in the opposite direction to the combined magnetomotive force of the coils Z) and c. There will then be no magnetic flow, the magnetoinotive forces neutralizing each other. The insertion of the magnetizable member j, however, provides a path along which these magnetomotive forces may cooperate, as indicated by the diagram in Fig. 2. It is evident that the insercoils capable of acting independently and exl tion of another member Will provide a path l with the plane of the contacting faces ot' the for the magnetic streams set up when the site directions.

The pivoted armature 5 ofthe electromagnet above described is pivoted to the exible o`r swinging member 9, which is actuated by springs wound about its pivotal bearings i3, but not shown, and adapted upon below normal Iiow of current through the magnet to carry the armature away from the pole-pieces. The cross-rod 14 is adapted to encounter the upper member of the latch lO to cause its actuation to release the movable switch 11 to permit its separation from the fixed contacts l2 in response to the actuation of spring-piston 18, which projects from cylinder 1G and bears against the upper part ot' switch member 1l.

An improved method ot' securing the arma ture 5 to its pivoted or iiexible supporting member 9 is shown in Fig. it. The armature is provided with a shank or projection l5 on its rear side, by means of which it is loosely pivoted to said supporting member 9, so that it will have sufficient vertical and horizontal play to permit its contacting face to coincide pole-pieces, thus securing perfect contact between them and without the necessity of nice adjustment of said supporting member and the consequent danger of injury by accidental impairment of said adjustment.

What I claim as my invention, and desire to secure by Letters Patent, is-

l. In combination with an automatic magnetic actuating device and an electromagnet for the control of its actuation consisting of a magnetic core having three or more legs, coils Wound on the core between and sepa y rated from each other by the legs and adapti ed to carry alternating currents, the currents in adjacent coils in different phase, and an armature adapted to cooperate with the legs.

In an automatic magnetic circuit-breaker having separable cooperative contacts, means for causing their separation, means for restraining said separating 1n eans,and an electromagnet as means for controlling the actuation of said restraining means consisting of a magnetic core having three or more legs, coils wound on the core between and separated from each other by the legs and adapted to carry alternating` currents, the currents in adjacent coils in dilerent phase, and an armature adapted to cooperate with the legs, substantially as described.

In an automatic magnetic circuit-break er, having separable cooperative contacts, means for causing their separation, means for normally restrainingthe separating means, a magnetic core having three or more legs, coils wound on the core between and separated by the legs, and adapted to carry alternating currents, the currents in adjacent coils in different phase, and an armature cooperating therewith as means for carrying magnetic streams not in phase with each other and providing alternative paths adapted for the maintenance of a continuous magnetic flow through the armature and core, the armature carried upon a spring-actuated lever which is adapted upon subnormal ilow through the said electromagnet to actuatc the above-mentioned restraining means, substantially as described.

VILLIAM M. SCOT'.

Witnesses:

JNO; Sronns Anims, E. F, GRACE.

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