US784722A - Automatic circuit-breaker. - Google Patents

Description

PATENTED MAR. 14, 1905.

E. P. WETMORE.

AUTOMATIC CIRCUIT BREAKER.

APPLICATION FILED OCT. 22, 1903.

2 SHEETS-SHEET 1.

I WITNESSES idwfi @QWM INYEIVTOH make, 3 4 TTOHWEY FsC-LZ am. a 7% PATEN'I'EI) MAR. 14, 1905.

1-]. P. WETMORE.

AUTOMATIC CIRCUIT BREAKER.

APPLICATION FILED OUT. 22, 1903.

2 SHEETS-SHEET 2.

Patented Marel'i 14, 1905.

PATENT OFFICE.

EARL PORTER lVElMORE, OF \VOLVERHAlVIPTON, ENGLAND.

AUTOMATIC CIRCUIT-BREAKER.

SPECIFICATION forming part of Letters Patent N 784,722, dated March 14, 1905.

Application filed October 22, 1903. Serial No, 178,069.

To (bl/Z whmn it may concern:

Be it known that I, EARL PORTER IV n'rnonn, of Wolverhampton, in the county of Stafford, England, have invented a new and useful Improvement in Automatic Circuit-Breakers, of

which the following is a full, clear, and exact description, reference being had to the accompanying drawings, which form a part of this specification.

My invention has relation to certain new and useful improvements in automatic circuitbreakers.

The objects of my invention are to provide an efficient and reliable instrument for automatically rupturing electric circuits of relatively high voltage whenever the current therein exceeds a certain predetermined maximum, which will operate automatically to restore the circuit after a short time interval, but which cannot close or be closed while a short circuit remains on the line which it protects, and which shall be simple and compact in its construction. To attain these objects, I employ a circuit-breaker of the well-known type, wherein movable and fixed contacts are held in circuit-closing engagement by means of a latch controlled by a trip-coil, which is connected in series with said contacts in the circuit to be protected, so that when the current flowing through said coil exceeds a certain predetermined maximum the latch is released and the contacts are separated to break the circuit. In connection therewith 1 provide a resetting-coil which is arranged when energized to again restore the contact engagement. This coil is connected in a circuit which is in shunt to the main circuit through the instrument and is normally open, means being provided, set in operation by the opening of the breaker, whereby this shunt-circuit is automatically closed after a short time interval, caused by the action of a retarding device operating upon the movable contact or contacts of the shunt-circuit-closing switch. Included in this shunt-circuit is an auxiliary coil whose function is to maintain the shuntcircuit closed while theinstrument is resetting, after which said coil is automatically shortcircuited and the shunt-circuit is opened.

To prevent the breaker from being reset while a short circuit remains on the line to be protected, 1 provide a locking device arranged to prevent the'shunt-circuit through the resetting-coil from being closed so long as any considerable amount of current remains on said line.

The exact nature of my invention will be better understood by reference to the accompanying drawings, in which Figure 1 is a front elevation of a circuitbreaker embodying my invention, with portions of the casing removed andthe parts in open-circuit position. Fig. 2 is a plan view of the resetting-coil, the latch, the latch-operated switch, and the parts adjacent thereto;

Fig. 3, a side view of the same, and Fig. i

a diagram illustrating the electrical circuits and connections.

The numerals 1 and 2 designate the main fixed contacts of the breaker, and 3 and 4 the relatively fixed auxiliary contacts of the same, preferably of hard carbon.

5 is a plunger upon which is a spindle 5, carrying a main contact 6, which is arranged to close the circuit between the main contacts 1 and 2, and an auxiliary contact 7, which is arranged to bridge the contacts 3 and 4. The spindle 5 may be positively connected to the plunger 5 or it may be a separate piece.

8 designates an arc-rupturing chamber surrounding the contacts 3, i, and 7, and 9 designates blow-out magnets.

As thus far described the breaker is of a well-known type.

The spindle 5 is held in circuit-closing position by means of a sliding jointed latch 10, whose nose engages the underside of a collar 11 on said spindle 5. 12 is a spring acting upon said latch to maintain its said engagement. The latch is pivoted at 13 and has an arm 14, which extends above'a solenoid tripcoil 15, which is in series in the circuit to be protected and with the said main and auxiliary contacts and which has a movable plunger 16.

17 is the auxiliary coil, whose connections, as shown in Fig. l, are such that under certain conditions it is connected in a shunt-circuit between one of the main terminals A of the instrument and ground, as hereinafter described. ing at its lower end a piece 19, of spring brass or copper, insulated from the plunger and carrying two contacts 20, which cooperate with two fixed contacts 21. Connected to the upper end of the said plunger is a rod 22 engaged by one arm of a lever 23, whose other arm engages the plunger 5. Seated between a head on the upper end of the rod 22 and the said lever is a coiled spring 24. 25 is a spring acting upon said lever to cause it to exert a downward pressure upon the plunger Connected to the lower end of the plunger 18 is a retarding device consisting, in the present instance, of a cord 25 wound several times about a drum 26 and connected to a light spring 27, which is arranged to oppose its resistance to upward movement of the plunger 18. On the shaft of this drum is an escapement-wheel 27 and cooperating therewith is an escapement-pawl 28 on a pendulum 29, the weight 30 of which is of magnetic material and is adjacent to the pole of an electromagnet 31. The high-resistance coil of this magnet is connected in a shunt between the two main terminals A and 2 of the breaker. (See Fig. 4.)

32 and 33 are two small fixed contacts, to which are connected the two terminals of the auxiliary coil 17. (See Fig. 4.)

34 is a conducting-piece carried by the latch and arranged to bridge the contacts 32 and 33. Contact 32 is connected to ground or the return side of the circuit through the resetting-coil 35, the core of which is formed by an extension of the plunger 5.

The operation is as follows: l/Vhen the current flowing through the series trip-coil exceeds the predetermined maximum, its plunger 16 is drawn upwardly against the arm 14 of the latch 10, thereby withdrawing said latch from underneath the collar 11 on the spindle 5. This causes said spindle to drop under the action of the spring 25 and opens the circuit. The spindle by this movement pulls down the engaging arm of the lever 23, and thereby throws its other arm upwardly, causing a compression of the spring 24. This spring now acts to pull up the plunger 18 against the opposing action of the retarding device, which may be set to give any desired amount of retardation, until the contacts are brought into engagement with the contacts 21. As will be readily seen from Fig. 4, this engagement of contacts completes a circuit through the auxiliary coil 17 and the resetting-coil 35, the circuit being from the main terminal A to the contacts 20 and 21, thence through coils 17 and 35 in series, and thence to ground. Coil 35 now acts to draw up the plunger 5 and reset the breaker. The purpose of the coil 17, as will now be clearly seen, is to hold up the plunger 18 and maintain the circuit through the coil 35 while the resetting operation is being performed. As soon as the This coil has a plunger 18, carryplunger 5 has been raised far enough to close the main circuit the nose of the latch 10 is, by means of spring 12, reengaged with the collar 11. This movement of the latch moves the conductor 34 into position to bridge the contacts 32 and 33. This short-circuits the coil 17, and the plunger 18 at once drops and opens the shunt-circuit. The upward movement of the plunger 18 is, as above stated, delayed by the retarding device. The chain or cord of this device, wound several times around the drum 26, is caused by the spring 27 to grip said drum sufiiciently to cause the rotation of the latter. and thereby of the escapement-wheel 27 This rotation is, however, retarded by the escapement 28. By increasingor diminishing the weight or by changing the length of its arm it may be made to vibrate faster or slower, with a corresponding increase or decrease in the time of operation of the switch. If a short circuit continues to exist on the line to be protected, current will of course continue to How through the coil of the magnet 31. The continued energization of this magnet holds the weight 30 of the pendulum 29 attracted thereby, thereby locking the escapement-wheel 27 and preventing any movement of the plunger 18. It is therefore impossible for the breaker to be reset so long as a short circuit remains on. the line to be protected. \Vhen no short circuit exists, the current liowing through the coil 31 is insullicient to cause the magnet to attract the weight 30.

The parts above described are capable of com pact and simple construction and arrangement, and the circuit-breaker is particularly adapted for usein the feeder systems of surfacecontact electric railways for preventing injury due to the formation of a short circuit at one of the contact-boxes; also for use in connection with switchboards and substations in lighting and tramway work in fact, wherever it is desirable to provide a protection against short circuits and to insure an automatic restoration of the circuitas soon as the short circuit shall have passed.

It will be readily understood that various changes may be made in the details of the construction and arrangement of the various parts without departing from my invention.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is*

1. In a circuit-breaker of the character described, the combination with a tripping-coil and tripping devices, of a resetting-coil, a shunt-circuit for said coil, a make-and-break switch for said coil, means for actuating the said switch arranged to be set in operation by the opening of the breaker, a retarding device for retarding the operation of said actuating means, and a locking device for preventing the operation of the said actuating means so long as a short circuit remains on the line protected by the circuit-breaker.

2. In a circuit-breaker, thecombination with automatic tripping devices, and automatic resetting mechanism, of a retarding device, acting to delay the resetting action, and positive locking means for preventing the action of the resetting means so long as a short circuit remains on the line protected by the circuitbreaker.

3. In a circuit-breaker of the character described, the combination with the trippinglatch and its actuating-coil, of the resettingcoil, the shunt-circuit therefor, a switch controlling such circuit, a spring for actuating said switch, and means actuated by the opening of the breaker for putting said spring into condition for operation.

4c. In a circuit-breaker of the characterdescribed, the combination with the trippinglatch and its actuating-coil, of the resettingcoil, the shunt-circuit therefor, a switch for controlling said circuit, a spring for closing said switch, and the lever actuated by the opening of the breaker and arranged to compress said spring.

5. In a circuit-breaker of the character described, the combination with the resettii'lgcoil, its shunt-circuit and switch, of means for closing said switch, arranged to be put in condition for operation by the opening of the circuit-breaker, and a locking device connected to the movable member of said switch, together with means whereby said locking device holds the switch against movement so long as a short circuit remains on the line protected by the circuit-breaker.

6. In a circuit-breaker of the character described, the combination with the resettingcoil, its shunt-circuit and switch, and means for closing said switch arranged to be put in condition for operation by the opening of the circuit-breaker, of a retarding device connected to the movable member of said switch, a locking device for said movable member, and an electromagnet connected across the main terminals of the breaker and controlling the operation of the locking device.

7. In a circuit-breaker, of the character described, the combination with the resettingcoil, its shunt-circuit, the controlling-switch for said circuit, and means for closing said switch, of an auxiliary coil for holding said switch closed while the resetting-coil is operating.

8. In a circuit-breaker of the character described, the combination with a resetting-coil, its shunt-circuit, the switch for controlling said circuit, and means for closing said switch,

of an auxiliary coil for holding the switch closed while the resetting-coil is operating, and means for short-circuiting said coil when the breaker has been reset.

9. In a circuit-breaker of the character described, the combination with the resettingcoil, its shunt-circuit, a controlling-switch l for said circuit, and means for closing said switch, of a retarding device connected to the movable member of the said switch, and consisting of a cord or the like, a drum around which said cord is passed and beyond which it is secured, and an escapement device in connection with the said drum.

10. In a circuit-breaker of the character described, the combination with a resetting-coil, a switch for closing the circuit of said coil, an electromagnetic lock for holding said switch against operation so long as a short circuit remains on the line, an auxiliary coil for holding the said switch closed while the resetting-coil is in operation, and means for subsequently short-circuiting the auxiliary coil.

11. In a circuitbreaker of the character described, the combination with a resetting-coil, a shunt-circuit therefor, a switch for controlling said circuit, a retarding device connected to the movable member of said switch, and means whereby said retarding device acts as a positive lock for said member so long as a short circuit remains on the line protected by the circuit-breaker.

12. In a circuit-breaker of the character described, the combination with the resettingcoil, its shunt-circuit and switch, of the auxiliary coil surrounding the movable member of said switch, and means for energizing said auxiliary coil by the closing of the said switch, said auxiliary coil forming a solenoid whereby said switch is, during the operation of the resetting-coil, held in closed position.

13. In a circuit-breaker of the character described, the combination with the trip-latch, and the resetting-coil, of the circuit-controlling switch for said coil actuated by the movement of the said latch.

14. The herein-described circuit-breaker having the tripping coil and latch, the resetting-coil, the shunt-circuit for said coil, the switch for controlling said circuit, the spring for closing said switch, the auxiliary coil for holding the switch closed, the retarding device for said switch, and the locking device arranged to hold said switch against movement under certain circuit conditions, all arranged to operate substantially as and for the purpose set forth.

15. In a circuit-breaker of the character described, the combination with a resetting-coil, and an automatic switch, which controls the circuit of said coil, of an escapement device in connection with the movable member of said switch for retarding the closing of the switch.

In testimony whereof I have affixed my signature in presence of two witnesses.

EARL PORTER IVEMORE. \Vitnesses:

A. B. HANBURY-SPARROW, MARTIN ALDnmvIoK.

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