US2250217A - Circuit-interrupting system - Google Patents

Description

July 22, 1941. E. w. BQEHNI' CIRCUIT INTBRRUPTIHG SYSTEI Filed Feb. 28, 1940 INSULATION nvento .m W e m am w m e 55' w i MWJ ,-clrcuit. breaker depends to some extent at least upon a Patented July22, 1941 UNITED STATES PATENT OFFICE 2,250,211 CIRCUIT-WW6 srs'rm New York Application February 28, 1940, Serial No. 321,235

- Claims; (01. 175-234) My invention relates to a circuitinterruptlng system and more specifically-to such a system employing a circuit breaker which depends for Since a circuit-interrupting system must interrupt the circuit at the proper time and in theproper manner, it is essential that the control equipment and associated apparatus cooperating with the circuit breaker to cause its operation do not fail at a. crucial time and, if they fall, that additional means be provided for protecting the Where the operation of the circuit source of fluid under pressure, there is always the possibility of 'a reduction or complete failure of the pressure of this source of fluid so that the protection given by the circuit breaker is nonexistent or at least doubtful. Therefore, means should be provided for insuring the interruption of the circuit in case of an abnormal-current condition even thoughthe source of fluid pressure upon which the operation of the circuit breaker depends to a certain extent fails for some reason or other so that the circuit breaker cannot be operated.

It is an object of my invention, therefore, to provide a circuit-interrupting system employing a circuit breaker which depends for its operation at least to some extent upon a source of fluid under pressure, wherein interruption of the circuit under abnormal conditions will occur even though there is a failure of the source of fluid under pressure so that the circuit breaker'cannot be operated satisfactorily.

trated my circuit-interrupting system as employing a circuit breaker of the cross fluid-blast type which is disclosed and claimed in the joint application of David C. Prince, William K. Rankin, .and Wilfred F. Skeats, Serial No. 303,126, filed November 6, 1939, and assigned to the same assignee as the present application. It will be understood, however, that this circuitinterrupting system may employ other types of circuit breakers which depend for their operation to a certain extent at least upon a source of fluid under pressure.

Referring now to the drawing, I have illustrated my invention as employing a fluid-blast circuit breaker .ll of the cross-blast type comprising a stationary contact II and a movable contact l2 arranged to be operated so as to draw an arc in an arc chute it. The fixed contact II is connected to the line terminal I4 while the movable contact I2 is connected to the lineter minal l5. Fixed contact II is provided with spring-pressed contact fingers Ila. and longer arcing contact fingers ll, whilecmovable contact i2 is provided with anarcing tip i2 so that, when the contacts separate, an arc therebetween occurs between arcing tips H and, I2. Immediately after separation of the contacts, one terminal of the arc is transferred by a blast of fluid, preferably air, issuing out of conduit it, from contact fingers H to the contact II" which is provided with a tip of arc-resistant metal. The air blast from conduit l6 upon opening of the breaker drives the are into the arc chute it against the edges of a plurality of partitions H in the arc chute, which partitions are transverse to the air gap and the ends of which extend close to the path of movement of the arcing tip l2 of the movable contact l2. The circuit breaker Ill, illustrated by way of example in order to describe my circuit-interrupting system, is notmy invention but is described and claimed in copending application Serial No. 303,126, referred to above.

In order to operate circuit breaker i6 automatically by fluid pressure, there is provided a.

cylinder it with a piston i9 connected through a rod 26 to operate a lever 21 secured to the shaft 22. The shaft 22 has attached thereto 'an arm 23 of insulating material for operating the V movable contact H of the circuit breaker.

1- though circuit breaker I0 is described with respect to a single phase, it will, of course, be understood by those skilled in the art that it may just as well comprise a plurality of phases,

.in which case, a plurality of arms 23 would be provided for operating the movable contacts I2 0! the various phases. The arm 22 is shown provided with a pin 24 operating the member 25 secured to the outer end of movable contact i2. Member 28 is arranged to slide on a pair of rods 26, only one of which is shown in the drawing since the other is obwured from view thereby. It wfll be apparent that, when the shaft 22 is rotated in a counterclockwise direction, the arm 23 will move the contact ii to the open position 23 will move the contact it to the closed DOSition. The member 25 and the rods 26 constitute a kind of cross-head arrangement by which the movable contact is reciprocated. This type of operating mechanism is described in detail in United.States Letters Patent 2,218,797, granted October 22, 1940, upon the joint application of Leonard J. Linde and Torild Andersen, and assigned to the same assignee as the present application.

In order to operate the circuit breaker in as well as to supply a blast of fluid through conduit is for arc-extinguishing purposes, a source of fluid pressure is provided which is preferably air under pressure. This source of air under pressure 27 is connected through a suitable blast valve 28 to conduit ii for supplying a blast of air adjacent contacts H and I? of circuit breakor i G for arc-extinguishing purposes. Blast valve 28 is normally biased to the closed position by means of spring 28 and is operated by rneans'of solenoid 39 which may be energized at the desired time by any suitable control circuit. The source of fluid 2? is also connected with the resoective ends oi" cylinder I8 for operating circuit breaker to through a four-way control valve 3i. valve is arranged to control the closing of circuit breaker ill by connecting source 21 with the right-hand end of cylinder l8 through conduit 32. For opening the circuit breaker, on the other hand, valve 3! is adapted to interconnect the source of fluid under pressure 21 with the left-hand end of cylinder 18 through conduit Valve 95 is so constructed as to vent one end of cylinder 53 to atmosphere through conduit 3% whenever the other end of cylinder is subjected to pressure from source 21. A suitable spring means 35 is provided to bias valve iii to the closed position shown in the diagram. Valve is arranged to be operated for opening circuit breaker I!) by means of an opening solenoid which may be energized from any suitable control circuit. Similarly, valve 8! is arranged to be operated to control the closing of circuit breaker by means ot a closing solenoid S? which also be energized from any suitable control circuit. Blast valve solenoid oper ug solenoid and closing solenoid 3 are prererably controlled in the manner disclosed and claimed in copending application Serial No. 310,599 of Bryce W. Wyman, filed December :22, 1939, and assigned to the same assignee as the application.

In the event that there is a reduction or complete failure of the pressure of source 21, it becomes impossible properly to operate circuit breaker Even if means were provided other than the fluid-operated means disclosed for producing relative movement between contacts H and i2, without a sumcient fluid blast from conduit it, the circuit could not be interrupted. In accordance with. my invention, however, for the purpose of clearing the circuit in the event that circuit breaker 10 cannot be operated due to an inadequate pressure at the source 21, I provide auxiliary interrupting means 38, which preferably may comprise a high-tension fuse which has a circuit-interrupting capacity comparable with that of circuit breaker III. This fuse or auxiliary circuit-interrupting means 38 is connected in series with terminal I! of circuit breaker 10 so that both circuit breaker I! and auxiliary circuit-interrupting means 38 are connected in the main power circuit 38. Fuse II is normally shunted by a switch 40 which may be of the air break or any other suitable type and this switch is arranged to carry substantially all the current in power circuit 39 when in the closed position so that very little current passes through auxiliary circuit-interrupting means ll.

The switch blade of switch 40 is provided with an extension 01' insulating material 40a to which is attached a spring 4! so as normally to bias the switch 40 to the open position. This switch is adapted to be latched in its closed position by means of a latching element 42 pivotally mounted so as to engage with extension 40a. Latch 42 is controlled by means of solenoid 43, the energization of which causes clockwise rotation of latch 42, thereby releasing extension 40a whereupon spring 4| movm switch 40 to the open position.

In order to make auxiliary circuit-interrupting means 38 eflective to interrupt the circuit in the event that circuit breaker I. cannot be operated and an abnormal current condition occurs in power circuit 39, I provide a suitable control circuit for solenoid 43 which is energized when the pressure of the fluid at source 21 is insufficient to allow proper operation of circuit breaker Iii.

This control circuit includes a pressure-respon-' sive relay 44 comprising a Sylphon bellows 4! connected to the source of pressure 2! and a suitable switch 46. Movement of Sylphon bellows 45 in response to the pressure of source 11 controls the operation of associated switch 46. The control power for energizing solenoid 43 may be obtained from any suitable source, such as 41. when circuit breaker i0 is in the open position, it would, oi course, be undesirable and unnecessary to open switch 40 in the event that pressure relay 44 operated in response to insufficient pressure at source 21 to close switch 46. Accordingly, limit switch 48 is provided to break the control circuit for solenoid 43 when circuit breaker i0 is in the open position. Switch 48 is connected with arm 23 and operated by movement thereof. In order to deenergize solenoid 43 after switch 40 has been opened, 1' provide a limit switch 49 operatively connected to extension 400. so as to be opened when switch M opened. It will be understood that switch 40 may be closed and latch '32 reset by any suitable means after the pressure at 2! has been restored to normal.

The operation of the circuit-interrupting system described above will be obvious to those skilled in the art since, it for any reason the pressure of the air or fluid in source 21 falls sufllciently so that it is undesirable or impossible to open circuit breaker HI in the event of an abnormal current condition, relay 44 will operate to close associated switch 46. Thereupon solenoid 43 is energized to release latch 52 from restraining switch 40 in theclosed position whereupon fuse 38 is connected to carry all the current in power circuit 38 and the latter is protected even though circuit breaker II cannot be operated. By this arrangement, protection 0! the circuit is insured in all cases.

While I have shown and described a particular embodiment. of my invention as applied to a circuit-interrupting system, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects and I. therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent 01 the United States is:

1. A circuit-interrupting system comprising a source of fluid under pressure, a main circuit breaker for interrupting said circuit which depends for its operation at least to some extent upon said source of fluid under pressure, an auxiliary interrupting ,device, mean normally maintaining said auxiliary interrupting device ineffective to interrupt said circuit, and means for controlling said last-mentioned means so that said auxiliary interrupting device becomes efl'ective to interrupt the circuit when said source of fluid pressure is inadequate to operate said mai circuit breaker properly. 1 I

.2. A circuit-interrupting system comprising a source of air under pressure, a main circuit breaker which depends for its operation at least to some extent upon said source of air under pressure, an auxiliary interrupting device having a capacity comparable with that of said main circuit breaker, a switch normally shunt ing said auxiliary device thereby maintaining the latter ineffective, and means for opening said switch so that. said auxiliary interrupting device becomes effective to interrupt the circuit when said source of air under pressure is inadequate to operate said main circuit breaker properly.

3. A circuit-interrupting system comprising a fluid-operated circuit breaker of the fluid-blast type for normally interrupting the circuit, a source or fluid under pressure for operating said circuit breaker and producing a blast of fluid for arc-extinguishing purposes, an auxiliary intempting device in said circuit having 2. capacity comparable with that of said circuit breaker, a switch normally shunting said am;- lliary device, and means for opening said switch when said source of fluid pressure is insufiicient to operate 'said circuit breaker properly.

4. A circuit-interrupting system comprisingin combination a source of fluid under pressure;

a main circuit breaker which depends for its operation at least to some extent upon said source of fluid under pressure, an auxiliary interrupting device having a capacity comparable .with that oi. said circuit breaker connected in said circuit, a switch normally shunting said auxiliary device, a pressure-responsive relay associated with said source 01' fluid pressure forfirst-mentioned means being dependent at least in part upon fluid from said source for proper operation thereof, additional interrupting means" for said circuit normally maintained ineifective to interrupt said circuit, and means responsive to a predetermined abnormal condition of said;

source of fluid for rendering said additional'interrupting means efiective to interrupt said cit-- cuit in response to an abnormal electricalicondition thereon. EUGENE W. BOEHNE;

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