US960995A - Lifting-magnet controller. - Google Patents

Description

J P. MOTZ.

LIFTING MAGNET CONTROLLER.

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960,995. Patented June 7, 1910.

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ATTORNEY UNITED STATES PATENT OFFICE.

JACOB F. MOTZ, OF PITTSBURG, PENNSYLVANIA ASSIGNOR TO THE ELECTRIC CON- TROLLER AND SUPPLY COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

LIFTING-MAGNET CONTROLLER.

To all whom it may concern:

Be it known that I, Jaooa F. Mo'rz, a citizen of the United States, residing at Pittsbur in the county of Allegheny and State of Iennsylvania, have invented or discorered new and useful Improvements in Lifting-Magnet Controllers, of which the following is a specification.

In the operation of lifting magnets, I have found that when the current is quickly broken, a high inductive voltage is generated in the magnet windings. This voltage I have measured and found it to be several times the normal voltage with which the mamet is excited. The presence of this high volta e I have found puts a strain on the'insulatlon of the magnet winding and on the wires going to the magnet. In the past it has been the practice to introduce a resistance in series with the magnet before opening its circuit. This decreases the current in the magnet and this reduces the inductive voltage enerated when the circuit is finally opened. To introduce resistance in series with a magnet as described above, requires the use of some form of controller having a rather large number of steps and a bank of resistance with a corres onding number of sub-divisions. Even tien the purpose of the controller can be defeated by a careless operator who may open the circuit of the controller so quickly that the current cannot be reduced to its proper value (due to the inductive effect of the magnet) and a severe flash will occur in the controller and a high inductive voltage be generated in the magnet. To overcome these difficulties, I have devised for magnets a controller that is independent of the speed, with which the operator moves the controller. This controller is simpler and smaller than a controller which inserts resistance in series with the windin of a magnet before opening the circuit of t e same.

Referring to the drawings, Figures 1 and 2 are diagrammatic views showm two of the many forms which my invention may assume.

Referring now to Fig. 1, I use a master switch or controller D and an electro-magnetically operated switch E. To ener ize the magnet, the handle of the switch is moved to the right so that the blade 2' makes connection with the contacts j and 7c and leaves connection with contact Z. Current Specification of Letters Patent.

Application filed December 17, 1907.

Patent-ed June 7, 1910.

Serial No. 406,851.

will then flow from plus line through the coil m of switch E, the contact A of the switch D, the blade 7'. and the contact j to the negative main. This will energize the coil m of the switch E and cause the arm a to make connection with the contact 0, which is joined to the positive main through the blow-out coil I. Current will then flow as follows: from the positive main through the contact 0, the arm n, and the magnet M to the negative main. To deenergize the magnet, the handle of the switch 1) is placed m the position shown and the magnet discharges as follows: from the terminal g to the lower terminal of the switch E, through the resistance It to the contact Z of switch D, through the blade 5 to the contact j, and thence to the terminal It of the mzwnet. It is to be noted that contacts II: and l overlap so that the resistance R is inserted before the switch E is opened. Switch E can be made to open quickly and may have the blow-out coil P attached to extinguish quickly any are formed at its contacts. Thus it will have a longer life than a switch with the time of opening dependent on the operator, who ma cause it to open slowly and the arc to en ure for a longer time.

Still another arrangement of my invention is shown in Fig. 2. In this arrangement I use two electro-magnetically controlled switches, a master switch or controller, and a bank of resistance. To energize the magnet the handle of switch F is moved to the right. so that the blade 8 makes connection with terminals t and u. Current then flows as follows: from the positive main through the coil 1 of the switch H, the contact a of switch F, the blade .9, and the contact If to the ne ative main. This closes the switch II and the current flows through the magnet as follows: from the positive main through the contact w of the switch H, the arm on, and the magnet to the negative main. To deenergize the magnet, the handle of the switch H is moved to the left until it assumes the position shown, when the blade 8 makes connection with the contacts t and v. The current then flows from the positive main through the coil d of the switch G, the contact a) of the switch F, the blade 8, and the contact t to the negative main. The magnet then discharges as follows: from the terminal 9 through the resistance R, the arm a of the switch G,

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the contact 2 to the terminal h of the magnet.

In both of the figures and description, I have shown and sioken of the contacts on the master controller or switch as overlap- )ing. It is ohvious that this is not ahsoutely necessary.

I. The combination of a lifting magnet having therein au energizing winding, a magnetically operated switch for connecting the winding of the lifting magnet to a source of current. a hunk of resistance, and a manually operated controlliu switch, said controlling switch being provided with contacts whereby, when it is moved from its till-position, the winding of said magnetically operated switch is ener ized and the circuit closed throu h the winding of said littin magnet, am when said controlling switch is moved to its otI-position. the said hunk of resistance is connected across the terminals of the winding of said lifting ma net through certain of the contacts of sait controllin switch.

2. The combination of an electric apparatus having an inductive winding, a magnetically-o rated switch connecting a source of e ectric energy to the said winding, a resistance, and a controlling handoperated switch having contacts arranged to close a circuit across the line wherehy. when it. is moved from its oil-position, the winding of the nnignetically operated switch is energized and circuit. closed through the said inductive winding, and when said controlling switch is moved to its otY-position, the said resistance is connected across the terminals of the said inductive winding.

3. The combination of an electric device having an inductive winding, a magneticalLv-operated switch connecting a source of euergv to the said winding. a resistance, a second magnetically-operated switch having contacts arranged to connect. the said inductive winding and the resistance in a closed circuit, and a hand-operated switch having contacts for closing the first magnetically-operated switch to energize the said electric device and for closing the second magnetically operated switch to connect. the said winding and resistance in said closed circuit when the contacts of the first. magnetically operated switch are ogcued.

bigned at Pittsburg, Ia., this 9ti day of December, 1907.

JACOB F. MOTZ.

Witnesses:

F. N. Banana, ANNA R. Bnam'.

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