US770007A - Time-limit circuit-breaker. - Google Patents

Description

PATENTED SEPT. 13, 1904.

E. M. HEWLETT. TIME LIMIT CIRCUIT BREAKER.

APPLICATION FILED EBB. 11.}899.

N0 MODEL.

'NVENTEIR. Edward M. HewIeHz.

WITNESEES.

by MM UNITED STATES Patented September 13, 1904,

PATENT OEEIcE.

EDWVARD M. HEIVLETT, OF SCHENECTADY, NEIV YORK, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, A CORPORATION OF NEl/V YORK.

TIME-LIMIT CIRCUIT-BREAKER.

SPECIFICATION forming part of Letters Patent No. 770,007, dated September 13, 1904.

Application filed February 11, 1899. Serial No, 705,239. (No model.)

To all whom, it may concern:

Be it known that I, EDWARD M. HEWLETT, a

. citizen of the United States, residing at Schenectady, in the county of Schenectady and State ,7

of New York, have invented certain new and useful Improvements in Time-Limit Circuit- Breakers, of which the following is a specification.

My present invention relates to time-limit circuit-breakers of the same general class as that described in my pending application, Serial No. 705,236, filed February 11, 1899. The utilities and advantages of this form of device are described in full in that application. It is sufficient for the purposes of this one to say that occasions frequently arise (particularly in large systems where the apparatus has capacity for sustaining considerable overloads for a short time) in which it is undesirable to open the circuit immediately upon the occurrence of an overload. I have therefore devised different forms of circuit-breaking apparatus which operate after a determinate time interval, which in that case and in this is called the time limit. If the causes of overload be removed within this time limit, the circuit-breaker does not operate at all; but if it still exists at the end of the time the circuit is opened in the usual way.

In the pending application referred to I have used electrical devices for tripping the circuit-breaker, the series coils merely acting to close the circuit of a relay-coil, while the latter does the mechanical work of opening the circuit-breaker. It is, however, possible to operate the invention beneficially in other ways, and one of these ways is set out in this application.

It consists, in brief, of a clock mechanism or spring-actuated wheel having a detent under the control of the series coil and provided, preferably, with an escapement or other retarding device of any desired form. hen the detent is removed by the action of the coil, the spring drives the wheel around and if the overload is persistent trips the circuitbreaker by means of a mechanical connection interposed in the path of a lug on the wheel.

If, however, the overload is removed, so that the armature of the series coil is released, the mechanical connection is droppedout of the path of the lug and the circuit-breaker remains set, the wheel'continuing its revolution until the lug brings up again against the detent.

The accompanying drawing shows the device in front elevation.

The circuit-breaker it is unnecessary to minutely describe, inasmuch as it is like in general that shown in the patent to IV. E. Potter, No. 533,083, and consists of circuit-breaking contacts operated by a toggle T, and having a latch or trip I, held in place by a spring K. A blow-out magnet is provided having a pole-piece R, and the whole, together with the time-limit device, is mounted upon a base A, of slate or other suitable insulating material.

The time-limit device consists of a magnetcore C, with a controlling-coil D upon it. I have shown the core as of laminated iron, the bolts illustrated serving to fasten the parts together, because in the particular installa tion for which the apparatus shown was designed alternating current is employed; but this is of course an immaterial feature, as a magnet of any suitable construction for the circuit controller may be employed. The armature E of the controlling-coil is held away from the core bythe spring H and is connected by a link F with another link, F, provided with a projecting lug f and attached to the trip I of the circuit-breaker. A springactuated escapementwheel G is also illustrated,having a lug upon its face and driven by the spring 9. Apendulum Q, with a weight g, by the adjustment of which the time of revolution of the wheel may be determined, carries the lugs Q, forming an escapement pawl.

The operation of the device as'a whole is as follows: l/Vhen the current rises in the coil D to a predetermined maximum, fixed in the usual way by the tension of the spring H, it attracts the armature E, drawing it up to its dotted-line position, in which the lug f is interposition and the circuit-breaker remains posed in the path of the lug g upon the wheel i G. The wheel is released and, if the current in the coil continues at the determined maximum, rotates, bringing the lug g against the lug f and pulling open the trip by the force of the spring. when the circuit is opened, current ceases in the coil D and the parts assume their illustrated position. If, however, before the lug g reaches the lug f the overload ceases, the parts resume their illustrated closed.

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

1. The combination, with a circuit-breaker, of a controlling-coil included in the same circuit, inoperative under normal conditions but operative under a predetermined maximum load, a time device having a rate of movement independent of variations in potential of the circuit, said time device being started when the coil operates, and connections between the time device and circuit-breaker for rupturing the circuit only after a predetermined time interval.

2. The combination of a circuit-breaker, a controlling-coil therefor inoperative under a normal current carried by the circuit-breaker but operative under predetermined abnormal current, a clock mechanism, and a mechanical connection between the clock and the circuitbreaker acting after a predetermined time to open the latter when a given overload per.- sists, but inoperative when the overload diminishes within the time limit.

3. The combination with a circuit-breaker,

of a time-limit mechanism consisting of a spring-actuated wheel, a lug on the wheel, a detent for the lug controlled by the circuitbreaker coil, a link connected to the trip of the circuit-breaker, a mechanical connection between the link and the detent such that both cannot be in the path of the lug at once, and a retarding device for the wheel.

4:. The combination with a circuit-breaker, of a time-limit mechanism consisting of a clock-train, a detent for the clock-train controlled by the armature of the series coil, a mechanical connection between the clock-train and the trip of the circuit-breaker, and a lug on one of the wheels of the clock-train so arranged that in its revolution it may engage with either the armature or the mechanical connection, but not with both.

5. The combination of a circuit-breaker, a clock mechanism having a pendulum-escapement, a lug upon a wheel of the clock, an armature for the series coil of the circuitbreaker in the path of the lug, a link connected to the trip of the circuit-breaker, and a second link connecting the armature to the first link, the second link being of such length that when the armature lifts, it brings the first link into the path of the lug in its revolution, and when the armature drops, the link falls below the path of the lug.

In witness whereof I have hereunto set my hand this 10th day of February, 1899.

EDl/NARD M. HElVLETT.

Witnesses:

B. B. HULL, EDWARD WILLIAMS, Jr.

Images