US1724863A - Time-limit device - Google Patents

Description

Aug. 13, 1929. L. s. WALLE ET AL 1,724,863

TIME LIMIT DEVICE Filed Jan. 25, 1926 h'wvencor 6 Harold \A/. Brown,

Ludv g' S. Wane, y M f Their Ak'bor ey.

Patented Aug. 13, 1929.

UNITED STATES PATENT OFFICE.

LUIJVIG S. WALLE, OF SCOTIA, AND HAROLD W. BROWN, OF SCHENECTADY, NEW YORK, ASSIGNORS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

TIME-LIMIT DEVICE.

Application filed January 23, 1926. Serial No. 83,411.

Our invention relates to improvements in time limit devices and more particularly to improvements in time limit electroresponsive devices, such as relays, for use in the protection of electric systems. An object of our invention is to provide an improved time limit electroresponsive device which is normally inactive but is definitely acuated only when an electric quantity such as the current of a circuit exceeds a predetermined value and which, without the expenditure of a relatively excessive amount of power, has almost instantly available at the expiration of a time dependent on the value of the electric quantity a force amply sufiicient to actuate a movable member for example one of a pair of relatively movable cooperating contacts.

Our invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims. a

The single figure of the accompanying drawing illustrates a time limit electroresponsive device embodying our invention. This device, in accordance with our invention, comprises a movable member 1 and means comprising an energizing winding 2 constructed and arranged to restrain the member 1 against movement when the current in the winding 2 is less than a predetermined value and to move the member when the current exceeds such value. For utilizing the movement of the member 1, when it attains a predetermined or critical speed, means such as a centrifugal mechanism 3 is provided. This speed responsive mechanism may be arranged to control an actuating means comprising one or more movable members 4 which may actuate one of a pair of relativel movable cooperating contacts 5, 6 arrange to control a circuit 7 such as, for example, the circuit of the controlling coil of a circuit breaker.

The movable member 1 and the controlling means therefor may be and is shown of the induction disc motor type, the member 1 being the disc which is secured to a suitably journaled shaft 8. The controlling means,

or motor element which is inductively related to the disc, is electromagnetic and as illustrated comprises a plural branched core 9 and a cooperating magnetic member 10 between the poles of which the disc 1 is mounted. The core 9 provides two magnetic circuits which comprise the core branches 11 and 12 and which have the common energizing winding 2. The core branches 11 and 12 are provided with shading or short circuited windings 13 and 14 respectively, which cooperate with the winding 2 to exert torques on the disc 1 in a well known manner. In order to have the centrifugal mechanism 3 normally inactive, these shading windings are so arranged that the torques are opposed and with current in the winding 2 less than a predetermined value, their re sultant effect is approximately zero, that is,

when the excitation of the driving magnet 910 is below a predetermined amount. In order, however, to have the centrifugal mechanism 3 positively actuated when the current in the winding 2 exceeds this predetermined value, that is to have a definite pickup point, the motor is arranged to provide a torque suflicient to accelerate the disc 1 and rotate it at a speed dependent on the current. For this purpose, one of the magnetic circuits, such as that comprising the core branch 12, may be arranged to saturate at the predetermined current as by providing the branch 12 with a portion 15 of restricted cross-section. Then when the current that is to say the excitation of the driving magnet 910 exceeds the predetermined value, the torque exerted by windings 2 and 14 is exceeded by the torque exerted by windings 2 and 13, and the greater the current the greater the difference between the torques.

The building up of the speed of the disc 1 will be retarded by the inertia of the rotating parts including the disc and the centrifugal mechanism 3. This mechanism may comprise, as shown, two weights or balls 16 pivotally mounted on a member, such as the shaft 8, which is rotated by the disc 1. At the expiration of a time dependent on the current in the winding 2 and the inertia of the rotating parts, the disc 1 will attain a 1 critical speed suiiicient to cause the weights 16 to fly out and raise a member such as a flanged collar or weight 17 which is slidably mounted on the shaft 8 and which may be biased to the position shown by a spring 18, as well as gravity. This collar- 17, when moved through a suitable distance, engages the controlling member A and in the arrangement shown opens the contacts 5 and 6.

1W ith this arrangement, the downward force comprising the weight of the collar 17, the bias of the spring 18, and the weight of the balls 16, tends to maintain the balls in the position shown. lVhen the disc 1 attains a speed such that the centrifugal force acting on the balls 16 is suiiicient to overcome this downward force, the balls fly out very quickly with considerable force. While the torque due to the weight of the balls 16 tends to increase as they move farther from the shaft, this increase is offset by the decrease in the torque exerted by the weight of the collar 17 and the bias of the spring 18 as the arms 19 of the ball-supporting levers move toward the shaft.

For varying the time action of the device, the balls may be arranged to fly out at dif ferent critical or predetermined speeds of the disc 1 in a number of ways, for example, by"

having the spring 18 adjustable so that. its force may be varied as by a nut 20 on the shaf 8-. V

r The force available to operate the contact mechanism, being derived from the accelera- 35 mined speed. Consequently, the relay is "so particularly applicable where it is desired to have circuit 0 ening action in circuit breaker control circuits on the occurrence of abnormal circuit conditions. By reason of the large available force,other suitable contact arrangements such as the well known toggle hand-reset type may, of course, be used. Vhen the winding 2 is deenergized as by the opening of the line circuit breaker, the disc 1 ceases to rotate and the weights 16 and the collar 17' resume the position shown in the drawing, the contacts 5 and 6' reclosing, if

desired, by having the weight distribution or the member 1' such as to tend to turn it counterclockwise or using suitable resilient means. V

While we have illustrated and described a "particular embodiment of our invention and more particularly described its application to a system wherein a single exc ting coil is responsive to the current. in a clrcuit so as to produce operation when a predetermined connected to respond to various circuit conditions according to the particular application that it is desired to make of our invention. We, therefore, aim in the appended claims to cover all such changes and modific'ations as fall within the scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States,

1. A time limit electroresponsive device comprising a movable member, means com prising an energizing winding for exerting opp'osing'forces on the member constructed and arranged to exert forces whose resultant efiect is approximately zero. when the winding is energized by current less than a predetermined value whereby to prevent movement of the member and to move the member when the current exceeds said value, a centrifugal mechanism arranged to be actuated upon movement of said member, and actuating means arranged to be controlled by the centrifugal mechanism when the member has acquired a predetermined speed.

2. A time limit electroresponsive device comprising a rotatably mounted member, means comprising an energizing winding for exertlng opposing torques on the member constructed and arranged to preventmovement of the member when the winding is energized by current lessthan a'predeter mined value and to move the member when the current exceeds said value, and a normally inactive centrifugal mechanism associated with the member and arranged to be actuated thereby.

3. A time limit electroresponsive device comprising an induction disc, electromagnetic means tending to rotate the disc in opposite directions comprising an energizing winding and two windings cooperating therewith, said means being constructed and arranged to hold the disc against movement when the current in'the energizing winding is less than a predetermined value and to move the disc when the current exceeds such value, and a normally inactive centrifugal mechanism arranged to be actuated by the 'disc when the disc attains a predetermined speed. 7 I

1. A time limit electroresponsive device comprising an induction disc, means tending to rotate the disc in opposite directions for normally holding the disc against movement comprising an electromagnet having two-flux circuits, an energizing winding for the flux circuits, one of said circuits being arranged to saturate with current in 'excessof a predetermined value in said winding whereby to effect rotation of the disc in one ofs'aid directions at a speed dependent on the value of the current in the winding, a normally inactive centrifugal mechanism arranged to be actuated upon a predetermined speed of rotation of the disc and relatively movable cooperating contacts arranged to be controlled by the mechanism.

5. A time limit electroresponsive device comprising an induction disc, a motor element for rotating the disc inductively related thereto and arranged to exert opposing torques thereon, and speed responsive means operative on the occurrence of an unbalance between said torques sufficient to move said disc at a predetermined speed.

6. A time limit electroresponsive device comprising a movable member, and electromagnetic means for rotating the member arranged with excitation below a predetermined amount to exert approximately equal opposing torques on the member and with excitation above said amount to bring the member up to a predetermined speed in a time dependent on the inertia of the memher and the amount of excitation, and circuit controlling means responsive to the speed of said member.

7 A time limit electroresponsive device comprising a movable member and a motor element for moving the member arranged to exert opposing torques thereon, and a normally inactive centrifugal mechanism operative on the occurrence of an unbalance between said torques sufiicient to move said member at a predetermined speed.

8. A time limit electroresponsive device comprising a rotatable member, a motor element for rotating the member arranged to exert opposing torques thereon, circuit controlling means and a centrifugal mechanism for actuating the circuit controlling means on the occurrence of an unbalance between said torques suflicient to move the rotatable member at a predetermined speed.

9. In combination, a member to be operated, a motor of the induction disc type having electromagnetic means for producing opposing torques on the disc arranged to balance each other when the energization of the elctromagnetic means is below a predetermined amount characterized by the fact that a portion of the electromagnetic means is arranged to become saturated on energization thereof above said amount whereby to unbalance the torques and move the disc, and means controlled by the disc for actuating the member to be operated.

In witness whereof, we have hereunto set our hands this 22nd day of January, 1926.

LUDVIG S. lVALLE. HAROLD lV. BROWN.

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