US2402479A - Arc furnace regulator switch - Google Patents

Description

June 18', 1946. J, YOUNG ARC FURNACE REGULATOR swmcn Filed Oct. 25, 1 943 2 Sheets-Sheet 2 lll'l INVENTEIR J.YDLINI3 AT'ru RNEYS Patented June 18, 1946 UNITED STATES PATENT OFFICE ARC FURNACE REGULATQR SWITCH John Young, Welland, Ontario, Canada Application October 25, 1943, Serial No. 507,648

This invention relates to improvements in arc furnaceregulators, and especially applying to those furnaces where the arc is submerged in the charge and where changes in the current passing. through the electrodes are of a. gradual nature.

In furnaces of this type and where the regulator is equipped with electric contact devices, the corn tact points very soon become burned pitted andcease to make contact. This is due to the very gradual change in the current density of the electrode which does not give enough pressure on the contact points to make an electric contact. For the above reason I use the knife edge type of contact as used on some of the earlier types of regulators, for instance, the Thury regulator. This regulator, however, had numerous mechanical and other disadvantagesit was purely a step by step regulator, the steps not being adjustable, a feature extremely necessary in order that it would function properly on the various types and sizes of furnaces.

The present invention overcomes these disadvantages and it is an object of the invention to provide an arc furnace regulator which is simple in construction, positive in its action, and in which contact is made indirectly by positive mechanical action.

A further object of the invention is to provide a regulator of this type wherein by simple adjustment the duration of contact may be readily determined.

With these and other objects in View, the invention generally comprises a regulator incorporating a swingable metering arm normally held in the neutral position under proper current conditions but swingable to one side or the other depending upon an increase or decrease in the current effected by the furnace electrodes, the metering arm carrying knife edge contacts cooperating with swingable contact arms as a mechanical movement for effecting proper contact to correct the abnormal current condition, said mechanical means being maintained completely out ofaction under normal current conditions.

--The invention will be clearly understood-by reference to the following detailed specification taken in conjunction with the accompanying drawings.

In the drawings: I

Fig. 1 is a front elevation of a regulatoraccording to the present invention illustrating the several novel features thereof; and i Fig.2 is a side elevation of Fig. 1. v 1 Referring to thedra'wings, l and H indicate Claims. (Cl. 200-104) the connections with a current transformer of an electric arc furnace, which latter is connected on either the high tension or low tension bus bars of the furnace transformer. The current-transformer is thus connected by way of leads i2 and being pivoted as at I8 so that it may oscillate about its pivot point. On each side of the arm ll adjustable stop members l9 and as are positioned to regulate the throw of arm H. Under normal conditions the arm I! is designed to be disposed vertically as shown.

The arm I! is in effect operatively connected with the horizontal rod 2| which, on the one hand, is connected with the dash pot arm 22 of a dash pot 23 which serves as a damper in respect to any vibration that may be set up, and, On the other hand, is connected with the coil spring 24 suitabl anchored to an adjustable anchoring member 25 through which the tension of the spring may be varied. The coil spring 24 serves to maintain the neutral position of the arm H. For instance, the regulation may be such that by adjustment the arm I! remains neutral when a current of two amperes passes through the solenoid coil. However, where there is a current increase the change reflected upon the solenoid coil l4 through the current transformer will cause the metering arm I! to swingto the left, whereas a drop below two amperes would cause' the arm to move to the right.

On the end of the metering arm I? is a knife contact member 26 provided with the upwardly directed knife edge 21 and downwardly directed knife edge 28. The knife edge 21 is designed to be positioned in the path of a finger 29 of a dog 30 when the arm [1 is moved to the left and conversely the knife edge 28 is designed to be positioned in the path of the finger 3| of a dog 32 when the arm I! is moved to the right. Each of these fingers is provided with a notch 33 which is positioned directly in the path of the knife blade under the circumstances mentioned, pro- 38. Each of these dogs has an arm 31 and 38 respectively extending on the opposite side of their pivot points and which carry the contact bars 39 and 40, the dogs being normally spring pressed by the bow spring 4| and connected to a suitable terminal 42 by the lead 43. The contact plates 39 and 40 are designed to cooperate with the spring contacts 44 and 45 respectively, the spring arms of which are carried on the rocker arms 46 and 41 each pivoted as at 48 on the plate 36 and normally spring tensioned by the coil spring 49 which tends to swing the contacts 44 and 45 away from each other, the distance of separation or location being regulatable by the regulating screws 50 and The contacts 44 and 45 are connected with the proper circuit in each case by the leads 52 and 53 respectively, operating in the respective circuit for winding or unwinding the winch motor.

The plate 36 is pivoted on pin 54 from a suitable base plate or panel A and derives an oscillating motion from an eccentric 55 which operates the arm 56 (see Fig. 2) connected with plate 36, the eccentric being driven through suitable reduction gearing operated by a small motor B. Consequently, as the plate oscillates back and forward on its pivot 54, under normal circumstances no action will result but where there has been a change in current due to changes brought about by the electrodes of the furnace and their position, a swinging of the metering arm I] to the left or the right results according to an increase or decrease in current. Either the finger 29 or the finger 3| of the dogs 30 and 32 respectively will contact with the knife contact member 26 since the latter will then be directly in the path of the fingers of one of these dogs. As a result, therefore, of contact between the blade contact member 26 and either of the dogs 30 or 32, contact plates 39 or 40 as the case may be will engage the corresponding contact 44 or 45 resulting in the completion of the circuit controlling the winch motor for either raising or lowering the electrodes of the furnace and contact will be maintained for a suitable dura tion depending upon the adjustment of the adjusting screws 5| so as to cause the motor to wind or unwind to the required extent.

From the foregoing it will be obvious that a positive acting regulator is produced which through the simple expedient of a knife edge and a unit actuated thereby will cause positive contact to be made, thus providing for eilicient operation and eliminating the burning and pitting of the electric contacts. In this connection it will be apparent that until the metering arm has been moved to the position where one of the knife edges is positioned to engage the mechanical unit for effecting contact, no contact will be made. Consequently, contact is only made at a predetermined change in current density which must result in a. positive contact.

What I claim as my invention is:

1. Switch means for controlling electrically operated apparatus responsively to electric current conditions in a circuit therefor comprising a solenoid designed to be operatively connected with the source of said current, and reactable to variations therein, a swingable arm movable by said solenoid and swingable in one direction or the other upon plus or minus variations in said current, means normally holding said arm in a neutral position, an oscillating member cooperatively related to said arm, contacts carried by said osclllating member and controlling secondary circuits, displaceable means engageable with said contacts upon displacemnt, for completing the secondary circuits, including projecting fingers disposed adjacent to said arm, actuating means carried by said arm and disposed out of the path of said fingers, in the neutral position of said arm, said actuating means being disposed in the path of one or other of said fingers upon movement of said arm, to cause displacement of one of said fingers, said secondary circuits being adapted to actuate a means to correct current varying causes in said apparatus.

2. Switch means as claimed in claim 1 in which the movable fingers are pivotally mounted adjacent one end of the oscillating member and designed to project therefrom to a position directly in the path of the actuating means carried by said arm when the latter is swung from the neutral position to the right or to the left.

3. Switch means as claimed in claim 1 including means for adjusting the position of said contacts to determine the duration of contact effected by said actuating means.

4. Switch means for controlling electrically operated apparatus, responsively to electric current conditions in a circuit therefor comprising a solenoid designed to be operatively connected with the source of said current and reactable to variations therein, a swingable arm cooperating with said solenoid and swingable in one direction or the other upon plus or minus variations in said current, means normally holding said arm in neutral position, an oscillating member cooperatively related to said arm and having contacts controlling secondary circuits, displaceable means, engageable with one of said contacts upon displacement, for completing one of said secondary circuits, said displaceable means including movable projecting fingers disposed adjacent to said arm, opposed knife edges carried by said arm and disposed out of the path of said fingers, in the neutral position of said arm, said knife edges being disposed in the path of one or other of said movable fingers upon movement of said arm to cause displacement of one of said movable fingers, said secondary circuits being adapted to actuate a means to correct current varying causes in said apparatus.

5. Switch means as claimed in claim 4 in which the movable fingers are pivotally mounted adjacent one end of the oscillating member and designed to project therefrom to a position directly in the path of the opposed knife edges carried by said arm when the latter is swung from the neutral position to the right or to the left, said fingers being connected with contact arms and being spring pressed to retain them in normal position until engaged by one of said knife edges to effect contact, said latter engagement swinging a contact arm against the pressure of said spring means, into contact position.

6. Switch means as claimed in claim 4 in which the movable fingers are notched for engagement with the knife edges and means is provided for stopping the arm in its movement to the right or to the left at a predetermined point to coincide with the position of the notch of either one of said fingers.

7. Switch means for controlling electrically operated apparatus, responsively to electric current conditions in a circuit therefor comprising a solenoid designed to be operatively connected with the source of said current and reactable to variations therein, a swingable arm movable by said solenoid and swingable in one direction or the other upon plus or minus variations in said current, means normally holding said arm in a neutral. position, an oscillating plate-like member swingably mounted from one end thereof and cooperatively related to said arm, said oscillating plate carrying contacts designed to control sec ondary circuits, a pair of opposed pivotally mounted fingers carried by the opposite end of such plate-like member and movable to engage said contacts for completing the secondary circuits, said fingers having projecting parts extended towards one another in spaced apart relation and located closely adjacent'to said arm, actuating means carried by said arm disposed out of the path of said projections, in the neutral position of said arm, said actuating means be ing disposed substantially between said projecting parts of the fingers and in the path of one or other of said projecting parts of the fingers upon movement of said arm to cause displacement of one of said fingers and its engagement with one of said contacts, said secondary circuits being adapted to actuate a means to correct current varying causes in said apparatus.

8. Switch means as claimed in claim 7 in which projecting parts are formed with notches, said actuating means comprising a pair of oppositely projecting knife edges disposed in spaced parallel planes, one of said knife edges being moved into alignment with one of said notches when said arm is moved in one direction or the other and means for stopping said arm in either direction of its movement to locate a knife edge accurately in alignment with one of said notches.

9. Switch means as claimed in claim '7 in which said contacts are pivotally mounted and means is provided for adjusting the spacing of said contacts relatively to said fingers.

10. Switch means as claimed in claim 7 in which said fingers are held in spaced relation to said contacts by a bow spring having substantially parallel spaced apart extremities, each of said extremities being fastened to one of said fingers, said fingers being swingable against the pressure of said bow spring when engaged by the actuating means of said arm to engage the adjacent contact.

JOHN YOUNG.

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