US2863019A - Relay system controlling release of isolating switches - Google Patents

Description

Dec. 2, 1958 A. KLIMESCH 2,363,019

RELAY SYSTEM CONTROLLING RELEASE OF ISOLATING SWITCHES Filed March 15, 1956 3 sheets-sheet 1 INVENTOR n-M J W :3, mph

ATTORNEYS Dec. 2, 1958 A. KLIMESCH' 2,863,019

RELAY SYSTEM CONTROLLING RELEASE OF ISOLATING SWITCHES Filed March 15, 1956 3 Sheets-Sheet 2 ATTORNEYS Dec. 2, 1958 b A. KLIMESCH I 2,863,019

RELAY SYSTEM CONTROLLING RELEASE OF ISOLATING SWITCHES Filed March 15, 1956 3- Sheets-Sheet 3 INVENTOR BY W 02v PW)JW 2 1 ATTORNEYS United States Patent RELAY SYSTEM CONTROLLING RELEASE OF ISOLATING SWITCHES 1 Alfred Klimesch, Gmunden, Austria, assignor to Aktiengesellschaft Brown, Boveri & Cie, Baden, Switzerland, a joint-stock company Application March 15, 1956, Serial No. 571,631

Claims priority, application Austria March 16, 1955 8 Claims. (Cl. 200-102) This invention relates to an improved arrangement for effecting automatic opening of the contacts of an isolating switch, or a similar switch having a relatively low disconnect rating, so as to isolate short-circuited portions of an electrical distribution system in the voltage and current free state. Disconnection of the short-circuit itself is eifected in the usual manner by means of power switches of sufiicient disconnecting power located at the feeding points in the system.

The known switching arrangements of a similar type require either connecting lines between the control devices for the isolating switches, or transformers, a source of direct current and a plurality of follow-up relays. Sue-h arrangements make the disconnection of short-circuits dependent upon the time of their cessation, but not on the absence of the voltage and expiration of a delay period following cessation of the short-circuit current. In such switching arrangements, isolating switches to be actuated in the current-free state cannot be used at all. Such switching arrangements are also generally costly and can be used only to a limited extent.

In accordance with the present invention, disconnection of the short-circuited portion or portions of the distribution system is effected in a most simple manner by an isolating switch controlled by means of a relay combination of an excess (short-circuit) current relay, and which includes also a time delay factor, and a voltage relay. These relays are so arranged that after the voltage has failed to reappear, and after termination of a time delay period following cessation of the short-circuit current, the isolating switch is released for automatic opening of its contacts. Moreover, the arrangement is such that the contacts of the isolating switch cannot be separated during the existence of the short-circuit current.

In a particular embodiment of the invention to be described hereinafter, the isolating switch is provided with contact means which are opened by means of a spring in which energy is stored. Release of the spring energy is controlled by a pawl, and actuation of the pawl is controlled by the armature elements of a current relay and a voltage relay acting conjointly in such manner that both armatures are required to be in the positions assumed when the relays are in an unenergized state before the pawl can be tripped to thus effect opening of the switch contacts.

The objects and advantages of the invention will become more apparent from the following detailed description of preferred embodiments and from the accompanying drawings which illustrate them.

In the drawings:

Fig. l is a schematic view of a power distribution system in which isolating switches constructed in accordance with the present invention are arranged; I

Fig. 2 is a view in side elevation of a power isolating switch having contacts which are opened by means of a releasing spring and a release pawl controlling operation of the releasing spring, the switch being provided, in accordance with the invention, with mechanism controlled jointly by an excess current relay, a voltage relay and a time delay interval in such manner that the release pawl and spring are actuated to effect opening of the switch contacts only upon an absence of the voltage and cessation of the excess current for the predetermined time delay.

Fig. 3 is a view similar to Fig. 1 showing an application of the invention to an isolating switch; and

Figs. 4-7 are somewhat schematic views of the isolating switch in accordance with Fig. 2 illustrating the various phases involved in its operating procedure.

Fig. 1 illustrates a distribution system for electrical power which includes two interconnected switching stations A and B. From these two stations start a plurality of high voltage main feed lines which can be disconnected by power switches LS having a high disconnecting power. On the feed lines are arranged a plurality of transformer stations T from which longer high voltage branch lines lead to additional transformer stations T1. Selective disconnection of any of the main or branch line sections when trouble occurs, is desirable. The arrangement of automatic power switches or fuses is not possible, however, for reasons of costs, space requirements and operation. A switch with a lower disconnecting power such as distribution switch TS is therefore provided. This latter switch can be either a power isolating switch or an isolating switch. The switch TS disconnects selectively within its disconnecting capacity overloaded sections of the mains, without impairing operation of the sound mains. When a short-circuit condition occurs, release of the isolating switch TS is at first blocked; It is opened, however, in an automatic manner with a time delay, after the two automatic power switches LS have been disconnected in the voltage free and current free state in stations A and B, so that operation can be continued without trouble, after the power switches LS have again been connected in the stations A and B. In the same manner, the isolating switch TS, which is not suitable, however, for the disconnection of excess currents,-disconnects selectively the trouble section of the line, after cessation of the short circuit current.

With reference now to Fig. 2, the power isolating switch indicated in general by SW1 is seen to be comprised of an upstanding support 1, an upper tubular stationary contact member 2 spaced laterally from the support by means of a horizontally extending insulator 3, and a movable contact in the form of a rod 4 which is arranged telescopically in a tubular member 5 of con ductive material that is likewise spaced laterally from the support 1 by means of a horizontally extending insulator 6. The rod contact 4 moves in a generally vertical direction to establish or break the connection between it and the stationary contact member 2. To this end it will be seen that rod 4 is articulated intermediate the ends thereof at 7 to one end of an arm 8 which is likewise surrounded by an insulator 9, the other end of arm 8 being pivotally connected to the support 1 on a rock shaft 10 that is actuated by linkage 11. In Fig. 2 the switch is shown with its contacts in closed position. To

elfect separation of the contact members 2 and 4, switch SW1 is provided with a spring (not illustrated), in which energy is stored, for moving arm 8 and contact rod 4 downwardly, this spring being released by means of a tripping member such as a release pawl 12. -The dual,-

R1 including a winding 13 adapted to be energized by the current and an armature 14 which is drawn inwardly of winding 13 when the latter is energized. This relay also includes a time delay feature illustrated by dashpot 51 which prevents the armature 14 from moving upward in the direction away from winding 13 until the latter has been deenergized for a predetermined time delay interval. Alternatively, the time delay feature may be incorporated in a separate relay but in either arrangement, the armature 14 is not to release until the shortcircuit current on the line has ceased for a period equal to the desired'time delay.

A bellcrank 1-5, pivotally mounted at 15 has one arm 15a thereof pivotally connected to arm 14 and the other arm 15b pivotally connected to one end of a generally horizontal insulated rod 16. The other end of rod 16 is pivotally connected to one arm 17a of a second bellcrank 17 pivotally mounted on support 1 at 13 and the other arm 17b is connected pivotally by a link 19 to a vertically arranged bar 2% which is guided for displacement longitudinally of itself in two spaced guides 2 l, 22. A tension spring 23 has one end connected to the lower end of bar 20 and the other end anchored to a lateral projection 1a on support 1, the spring 23 exerting a downward force, as indicated by the lower arrow, on bar 2543 in opposition to and which is overcome by an upward lifting force, indicated by the upper arrow, exerted on bar 29 acting through link 19, bellcrank 17, rod 16, bellcrank 15 and armature 14 when the winding 13 of current relay R1 is energized, thus causing these elements to take positions indicated by broken lines in Fig. 2. It is thus evident that the position of bar 20 is determined in part bythe condition of relay R1.

The control imposed upon the opening operation of the contact members of switch SW1 by the voltage on the system includes a voltage relay R2 having a winding 25 which is energized by the voltage at the operating point, which latter may be a station transformer, or a voltage transformer, or the Voltage in a branch line on the system. The armature element 26 of relay R2 which is drawn to the left when winding 25 is energized has one end articulated to one end of a lever 27, the other end of lever 27 being pivotally connected at 28 on a stationary pi ot. A link 29 has one end articulated to the movable end of lever 27 and the other end of link 2 is articulated to the movable end of a lever 39, the opposite end of lever 30 being pivotally connected at 31 to the bar 2t A leaf spring 32 has one end fixed to bar .24} and the free end of spring 32 bears against lever 34} in such direction as to urge the latter in a clockwise direction of rotation about pivot 31 to the position shown in full lines in Fig. 2 wherein the lever 30 is longitudinally aligned with bar 20. As is evident from Fig. 2, energization of winding 25 of voltage relay R2, drawing armature 26 to the left acts thru link 29 to rotate lever 30 in a counterclockwise direction in opposition to the counteraction of spring 32. The end of lever 30 to which link 29 is articulated includes a horizontally projecting portion 30a at the outer end of which a roller 33 is mounted. This roller is adapted to move beneath a laterally projecting arm 12a on release pawl 12 when bar 20 is raised upon energization of relay R1 with current of short-circuit magnitude and when voltage relay R2 is energized. When voltage relay R2 becomes deenergized and bar 20 occupies its raised position, spring 32 will move lever 38 clockwise thus to shift the roller 33 to the right as to move over a second laterally extending arm 12b on release pawl 12. Assuming the current relay R1 now to be deenergized, its armature will be permitted to release and move upward upon expiration of. the time delay associated with this relay thus permitting the energy stored in tension spring 23 to pull bar 26 downward. As bar 2% moves downward, lever 30 and roller 33 are likewise carried downward thus rocking release pawl 12 about its pivot 12c and hence releasing the spring (not illustrated) by which arm 8 and contact rod 4 are caused to move downward thus separating contact rod 4 from its complementary stationary con- 4 tact member 2. The contacts of the switch can be reclosed later by actuation of the linkage 11.

From the above it will now be evident that cooperation of the current and voltage relays R1 and R2 are required to release the pawl 12 by which the contacts on the isolating switch SW1 are caused to open. In the presence of a voltage on relay R2, roller 33 bears against the under side of arm 12a of pawl 12 and hence renders counterclockwise rotation of pawl 12 impossible thus preventing the contacts of the isolating switch Swll from being opened either automatically or by hand. Also, during the presence of any short-circuit current on relay R1, or within the time delay period after cessation of the short-circuit current, the armature of. relay R1 cannot be released thus preventing spring 23 from pulling bar 2 and roller 33 downward, even though the armature of voltage relay R2 has been released. The contact members 2 and 4 of switch SW1 are thus opened only when voltage relay R2 is deenergized so that roller 33 engages arm 12b of release pawl 12, the current relay R2 has become currentless, and the time delay period following cessation of the short-circuit current has expired. A brief response of the current relay R1 with repeated short-circuit switching of the main power circuit breakers will bring about a response of the mechanism according to the invention but not a release, not even after the short-circuit current has ceased, if the voltage relay R2, due to reappearance of the holding voltage, has responded during the running of the time delay period.

Figs. 4-7 depict various positions for the operating components inaccordance with the invention. In Fig. 4, current relay R1 has not been energized but voltage relay R2 is energized. Thus bar 2t) occupies its lower position and lever 30 is pulled to the left thus readying roller 33 to be raised past the lower arm 1211 on release pawl 12. These positions are occupied when normal electrical conditions exist on the system.

In Fig. 5, a short-circuit has occurred thus energizing excess current relay R1, raising bar 20 and bringing roller 33 up against the under side of pawl arm 12a, voltage relay R2 still being energized.

In Fig. 6 the voltage relay R2 has become deenergized, thus moving roller 33 to a position above arm 12b of pawl 12. However, bar 20 cannot move since the armature on the current relay R1 has not yet released.

In Fig. 7 both relays R1 and R2 are deenergized, the time delay period has elapsed, the release pawl 12 has but which does not reach the high level (short-circuit condition) required to effect lifting of the bar 20. To this end it will be seen that current relay R1 also controls a second lever system comprising bellcrank 35 associated with a second armature component 52 of relay R1, an insulated rod 36 articulated at one end to an arm of bellcrank 35 and at the other end to one end of a dogleg lever 37 pivoted at 18 intermediate its ends, the other end of lever 37 being articulated to one end of a link 38 having its otherend articulated to an arm 12d on release pawl 12. Thus when excess current is applied to relay R1, armature 52 is pulled in, rod 36 is pulled to the right, shifting link 38 obliquely upward to the left and rotating release pawl 12 counter-clockwise to efiect release of the spring mechanism which, in turn, effects separation of the switch contacts 2, 4. This sequence of events will occur only if current relay R1 has not been excited by a current of short-circuit magnitude which, as previously explained, prevents opening of the switch contacts until a given sequence of events has taken place.

Fig. 3 illustrates a slightly different embodiment of a switch equipped with the coordinated voltage and current relay controlled contact operating mechanism but which has a lower power rating than the switch shown in Fig. 2. The switch SW2 of Fig. 3 is thus commonly known as an isolating switch. The contact members 2 and 4 of switch SW2 are generally the same as in switch SW1 of Fig. 2. However, the means for moving the contact rod 4' in the vertical direction is slightly difierent, it being noted that linkage 11 connected to the lower end of rod 4 projecting below guide sleeve 5 is used for such purpose. The arrangement of the current and voltage relays and the mechanism controlled thereby is generally the same as that shown and described with respect to the power isolating switch SW]. of Fig. 2. Consequently, corresponding components have been indicated with the same reference numerals but with primes added for purpose of distinction, and no further description thereof is considered to be necessary. However, the embodiment of Fig. 3' does include an additional safety device for locking the contacts of the isolating switch SW2 in the closed condition so as to prevent inadvertent separation of those contacts while current is still passing through them. To this end it will be seen that a second bellcrank 40 is associated with a second armature element 53 of current relay R1, this bellcrank being articulated to one end of an insulated rod 41, the other end of rod 41 being articulated to one arm of another bellcrank 42 and the other arm of hellcrank 42 being articulated to the upper end of a second guide bar 43 which is arranged at the side of bar 20 and guided longitudinally of itself by spaced sets of guides 44, 45. In a manner similar to bar 20, the bar 43 is urged in the downward direction by means of a biasing tension spring 46 having one end secured to the lower end of bar 43 and the opposite end anchored to a lateral projection 1b on support 1'. Spring 46 is preferably made adjustable so that the downward biasing force on bar 43 can be varied and this adjustability can be efiected by making projection 1b adjustable in the vertical direction. To this end, projection 1b is provided with an elongated vertical slot 48, and bolts 49 passing through this slot into the support 1 secure projection 1b to support 1 in any vertical position within the range of movement of the slot 48 along the bolts 49. In the current-carrying state, the armature 53 on relay R1 pulls rod 41 to the right, even when the excitation of the winding 13' on this relay is comparatively low, thus pulling bar 43 upwardly until a stop 43a thereon bears against the underside of a third lateral projection 12s on pawl 12 thus preventing the pawl from being rotated about its pivot and thus preventing the contact actuating spring of the switch from actuating the contacts.

The power isolating switch of Fig. 2 and the isolating switch of Fig. 3 can also be provided in known manner with mechanical or electrical indicating devices to show the on and off positions of the switch contacts.

In conclusion, it will be evident that the present invention affords an economical and most practical manner for automatic control of the contacts of an isolating or power isolating switch in the opening direction and in such manner that contact opening is initiated only when the voltage has ceased and the current flow has stopped for the duration of the predetermined time delay period. Also, while two embodiments of the invention have been described, it will be evident that various changes in the construction and arrangement of component parts may be adopted without, however, departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In an electrical switching device including a pair of relatively movable contact members and means including a tripping member for effecting disengagement of said contact members, a short-circuit current relay, a voltage relay and interconnected mechanical means controlled conjointly by said relays and actuated upon termination of a predetermined time delay period subsequent to cessation of the current flow in said current relay and in the absence of a voltage applied to said voltage relay for operating said tripping member.

2. An electrical switching device as defined in claim 1 wherein said mechanical means is arranged to lock said tripping member against movement so long as a shortcircuit current is applied to said current relay. I

3. An electrical switching device as defined in claim 1 wherein said voltage relay controls a member of said mechanical means preventing operation of said tripping member so long as a voltage is applied to said voltage relay.

4. In an electrical switching device including a pair of relatively movable contact members and means including a tripping member for effecting disengagement of said contact members, a short circuit current relay, a voltage relay, mechanical means conditioned by energization of said current relay with a current of short-circuit magnitude for actuating said tripping member upon termination of a time delay period subsequent to cessation of said current and the removal of voltage from said voltage relay, and means effective during energization of said voltage and current relays for preventing operation of said tripping member actuating means.

5. In an electrical switching device including a pair of relatively movable contact members and means including a tripping member for effecting disengagement of said contact members, a short-circuit current relay, a voltage relay, mechanical means including a bar movable longitudinally of itself from a spring loaded rest position upon energization of said current relay with a current of short-circuit magnitude, means carried by said bar for engaging said tripping member upon movement of said bar to prevent operation of said tripping member when said current relay is energized with short-circuit current, and means actuated by and upon deenergization of said voltage relay for changing the position of said means carried by said bar so as to reengage said tripping member in such manner as to effect its operation and hence disengagement of said contact members as said bar moves back to its position of rest upon termination of a time delay period subsequent to cessation of said short-circuit current.

6. An electrical switching device as defined in claim 5 wherein the means carried by said bar to prevent or to effect operation of said tripping member is comprised of a lever pivoted to said bar and a roller mounted at the end of said lever for engagement with said tripping member, and said means actuated by said voltage relay is constituted by a link interconnecting said lever with the armature element of said voltage relay.

7. An electrical switching device as defined in claim 5 and which further includes mechanical means controlled by and responsive to a lower order of current in said current relay for actuating said tripping member and effect disengagement of said contact members.

8. An electrical switching device as defined in claim 5 and which further includes a second bar arranged generally parallel with said first bar, said second bar also being movable longitudinally of itself from a spring loaded rest position upon energization of said current relay with a current lower than short-circuit magnitude, and said second bar including a member thereon engageable with said tripping member when said bar is moved to secure said release pawl against such movement as would effect disengagement of said contact members.

References Cited in the file of this patent UNITED STATES PATENTS 1,029,753 Harris June 19, 1912 1,919,466 Iansson Jan. 25, 1933 2,319,279 Watkins May 18, 1943 2,616,999 Bohn Nov. 4, 1952 2,678,361 Mitchell May 11, 1954

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