US895135A - Controlling system for lifting-magnets. - Google Patents

Description

Riv-1mm) AUG14, 1908; R.I.WRIGHT.

' CONTROLLING SYSTEM FOR LIPTING MAGNETS.

- APPLICATION ITILED APR. 10, 1908.

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ATTORN EV been shunt wound onrT D STAT PAT T nEL'BEX. I, WRIGHT, or cLEvELAND,

To all may concern:

Be it knownthat I, REUBEN I. YVRIGHT, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented or discovered new anduseful Improvements in Controlling Systems for Lifting-Magnets, of which the following is a specification.

My invention relates to a new andjmproved system of control forlifting magnets.

As far as I know, all lifting magnets have and connected directly across the supply mains, or'with'permanent resistances in series with 1 Under these conditions, the current which flows through the magnet depends on the resistance of the magnet circuit and the vol-' tage of the mains where the magnet is connected. When lifting magnets are attached to eiectric'hoistsor cranes, the voltage of the supply mains at the crane or hoist is at its lowest value just as the magnet is being hoisted away from the pile of maghetioinaterial, on which it is working.

principally'to two causes: First, more current is required to accelerate the hoisting mechanism, the magnet and the load than is required after the load has left the pile; and second, with an excited lifting magnet resting on a pile of magnetic material, the

separate the magnet and its pi e than to hoist the {magnet and load after the load has been lifted from thepile. This increased current causes an increased drop in e crane and thus a drop of curvoltage at til rent in the magnet circuit.

I have oliserved that the lifting capacity of a inagnetis roportional-to the current flowing through ItS WlIKhH and that after a load of magnetic materia has been lifted an" from thedpile, this current may-be materiaily reduce without causing the magnet to drop its load. It is therefore seen that a shunt magnet has a minimum current through its shading 'ust at the time that a maximum current is (l esirable and it has a maximum current when it is desirable to have a minimum current. Such a magnet therefore loses in lifting capacity, and its winding is subjected to greater heating than is desirable.

My invention overcomes these objections and supplies means whereb a greater current may be caused to flow t rough the magtheir wind ings This is due a greater pull to' load from the H OHIO, assIeNoR To THEELECTRIc CONTROLLER AND SUPPLY COMPANY, OF CLEVELAND,

OHIO, A CORPO RATI\ON QF OHIO.

CONTROLLING SYSTEM FOR LIFT'ING-MAGnn s'.

o' iPatented Aug; 4, .1908. v

Application flle d April 10, 1902. Serial 4 6,207.

1 net winding just as the magnet and load are leaving the pile, and later to automatically reduce thiscurrentnnd theconsquent unnecessary heating of the magnet winding.

same load with less heating;

My invention, is illustrated the accompanying sheet of drawin s' which shows a diagrammatic view thereog -On the drawing, S is a double-pole knife switchwhich connects the motor and magnet circuits to a suitable source of electrical energy'. From the positive pole of this switch current is led by of the relay 0, from which winding the current passes through the motor controller switch C when closed and through the arma- The wire 2 connects the contact I) of the 'magnet controller B to the wire 1 which is connected to the positive side of the switch S.

nected by the wire 3 tothe contact 6 of said cont-roller B, whose arm b carries the brush 6 arranged to bridge the contacts VI) and b when the controller arm I) is swung to the left. I; The arm 8 carries the contact 8, which c0 trolled by the winding 0. The contact 0' is connected through the winding 0 and the wire 1 to the positive side if the switch S and thecontact 0 is connected through the winding 8 of the switch S to the wire 4. The winding s controls the core 3 connected to s and s to be closed when the winding .9 lifts the said core: I

b. to the left so that brush 1)! spans the conthe magnet winding M as follows: from the caries.

This allows a magnet to lift a greater load with the same heating of windings or the the wire :1 to the winding 0 i ftureA and its field F to the negative pole of The movable arm sf of the switch S is con-- operates with the fixed contact 8', to whiched, the remaining end of the magnet winding and 0 arranged to be bridged by the switchor contacto, which carries a core 0? con-'1' i the switch arm 8 so as to cause the contacts If the switch B is closed by moving its arm tacts b and b, a circuit is established through "positive side, of the switch S through thewires 1 and 2, the contacts b, b, and b, the wire 3, the resistance R, the winding M and the wire 4 to the negative side of the switch S. In this circuit the winding M is in series with the resistance R and connects both across the line. If now thecontroller or switch C is closed, current is established through the motor circuit as follows: from the positive side of the switch S, through the wire 1, the relay'coil 0, the switch C, the armature A and the field F to the negative side of the switch S. As stated before, the current through the motor at starting is large. It, therefore, energizes the relay coil 0 sufficiently to cause the core '0 to rise so that switch '0 bridges the contacts 0' and 0, thus establishing a circuit as follows :from the positive side of the switch S through the wire 1, the coil 0, the contacts 0, 0 and 0, the coil 3 of the switch S, and the wire 4 to the negative side of the switch S. This circuit energizes the coil 8 so as to cause it to raise the core 8 and close the contacts 8' and The closing of these two contacts shunts the resistance R with the arm .5 of the switch S. This shunt permits a larger current to flow through the magnet M, the circuit now being as follows: from the positive side of the switch S, through the wire'l, the wire 2, the

contacts b b and b the wire 3, the arm s, the contacts .9 and s, the magnet winding M, and the wire 4 to the negative side of a switch S.

By the proper adjustment of the relay 0, the core 8 may be caused to remain in its upward position until the hoisting motor has lifted the magnet and the load from the pile, and all the moving parts brou ht up to speed. When this has occurred, the current t rough the hoistin motor and the relay coil 0 has gradually decreased until the relay is nolonger able to hold up its core 0. When the core dro s, the circuit of the switch coil s v of switch is opened at the switch 0 and the arm 8 opens the contacts s and s, which re-inserts the resistance R in series with the magnet winding M and decreases the current throu h the magnet, thus reducin its heat ing. if the resistance R is properly proportioned, the current in the winding may be materially reduced without causing the mag- ,net to dro any of its load.

When t reload has been transferred to the desired osition, it may be released from the ma net ynioving the arm I) of the switch 13 to t e right so that the brush 12 leaves con tact with the contacts 6' and b.

I claim 1. In a controlling system for lifting magnets, an electric motor, "a lifting -magnet winding in shunt with the motor circuit, and means for automaticallyinserting resistance in series with the said winding.

2. In a controlling system for lifting magnets, an electric motor, a lifting-magnet winding, and means for automatically decreasing the current in the said winding after the said motor has been accelerated.

3. In a controlling system for lifting magnets, an electric motor, a lifting magnet winding in shunt with the motor circuit, and means governed by theicnrrent in the motor circuit for automatically controlling the amount of current flowing in the said wind.- ing.

4. In a controlling system for lifting magnets, a lifting-magnet winding, a resistance in series with said winding, an electro-mags net, contacts controlled by the electro-magnet to shunt said resistance, an electric motor, a relay winding in the motor circuit, contacts controlled by the relay winding and controlling said electro-magnet, and a switch to close the circuit of the magnet winding.

5. In a controlling system forlifting 1nag-' nets, a lifting-magnet winding, a resistance in series with the said winding, an electromagnet, contacts controlled by said electro magnet to shunt the resistance, an electric motor, a relay winding in the motor circuit, means actuated by said relay winding during the rush of current in the motorcircuit be-.

fore the motor has been accelerated to shortcircuit said resistance.

Signed at Cleveland, Ohio, this sixth day of April, A. D. 1908.

REUBEN I. I VRIGHT.

Witnesses: i

C. PmTLE, H. M. DrEMnR.

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