US2463029A

US2463029A - Circuit interrupter

Info

Publication number: US2463029A
Application number: US706735A
Authority: US
Inventors: Francis J Fry
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1946-10-30
Filing date: 1946-10-30
Publication date: 1949-03-01
Anticipated expiration: 1966-03-01

Description

March 1, 1949. FRY 2,463,029

CIRCUIT INTERRUPTER Filed Oct. 30, 1946 4 Sheeds-Sheet 1 WITNESSES:

INVENTOR Z4 Fame/5155A March 1, 1949. J FRY 2,463,029

CIRCUIT INTERRUPTER Filed Oct. 50, 1946 4 Sheets-Sheet 4 WITNESSES: INVENTOR Patented Mar. 1, 1949 CIRCUIT INTERBUPTER' Francis J. Fry, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation,

East Pittsburgh,

Pa., a corporation of Pennsylvania Application October 30, 1946, Serial No. 706,735

This invention relates to circuit interrupters in general, and, more particularly, to improved arc-extinguishing structures therefore.

A general object of my invention is to provide an improved circuit interrupter of the type providing a pair of parallel disposed arc-extinguishing units, one of the units being particularly suitable for interrupting high current power arcs and the other unit being especially adaptable for the interruption of relatively low currents, such as low value magnetizing currents or charging currents. Preferably I employ improved current responsive means for selectively determining in which unit the circuit will be interrupted so as to have the circuit interrupted in the unit which is particularly adapted for the current being interrupted.

In United States patent application, Serial Number 465,244, filed November 11, 1942, now U. 8. Patent 2,406,469, issued August 27, 1946, to Leon R. Ludwig, Winthrop M. Leeds and Benjamin P. Baker, and assigned to the assignee of the instant application, there is disclosed and claimed a circuit interrupter of the liquid break type in which multi-orifice plate structure is disposed adjacent to the interrupting arc to effectively direct the oil into the interrupting arc to effect the extinction thereof. This type of interrupter has been demonstrated to show that the arc voltage encountered is extremely low and effective deionizing conditions are brought to bear upon the interrupting arc to effectively extinguish the latter in a very short period of time. The orifices in such a structure are designed to carry sufllcient liquid or oil flow in such quantities as to bring about the fast interruption of high power interrupting arcs.

However, during the interruption of low value currents, such as charging currents, the orifices normally used to interrupt power currents of larger magnitude may be too large to effectively direct oil flow against such small arcs.

It is a further object of my invention to take advantage of the remarkable interrupting ability of a multi-orifice type of interrupting structure, such as that described in the above patent application, by employing two such inter- 18 Claims. (Cl. 200-450) Another object is to provide an improved circuit interrupter oi the foregoing type in which improved means are provided so that the circuit will always be closed in the high power interrupting structure and not closed in the low power interrupting structure, the elements of which are relatively small.

Another object is to provide an improved hydraulic operating mechanism for a liquid-type circuit interrupter embodying two such multiorifice interrupting structures in parallel.

A further object is to provide a mechanical operating mechanism which will also achieve the selectivity desired.

Further objects and advantages will readily become apparent upon a reading of the following specification taken in conjunction with the drawings, in which:

Figure 1 is a side elevational view, partially in section, oi! a tank-type liquid break circuit interrupter embodying my invention and shown in the closed circuit position;

Fig. 2 is a vertical enlarged sectional view through the right hand arc-extinguishing assemblage of Figure 1, the contact structure being shown in the closed circuit position;

Fig. 3 is a view similar to Fig. 2 but showing the disposition of the contact structure during the interruption of relatively low currents;

Fig. 4 is a sectional view taken along the line IVIV of Fig. 2, looking in the direction of the arrows;

Fig. 5 is a diagrammatic view of the circuit interrupter of Figs. 1-4 showing the disposition of the contact structure during the interruption of relatively high currents;

Fig. 6 is a curve showing the contact travel of the movable contact in the low current unit as a function of time;

Fig. 7 is a vertical sectional view through a modified type of arc-extinguishing assemblage, the mechanism being mechanical, and the contact structure being shown in the closed circuit position;

Fig. 8 is a sectional view taken along the line VIII-VIII of Fig. '7 looking in the direction of the arrows;

Fig. 9 is a diagrammatic view of the interrupter of Figs. 7 and 8 showing the disposition of the contact structureduring the interruption of relatively low value currents; and

Fig. 10 is a diagrammatic view similar to Fig. 9 but showing the disposition of the contact structure during the interruption of relatively high value currents.

Referring to the drawings, and, more particularly. to Figure 1 thereof, the reference numeral l designates a tank filled to the level 2 with a suitable arc-extinguishing fluid 3, in this instance circuit breaker oil. Depending from he cover 4 of the tank I are terminal bushings 5, to the lower ends of which are threadedly secured and clamped arc-extinguishing assemblages generally designated by the reference numeral 6.

The arc-extinguishing assemblages 9 are electrically interconnected in the closed circuit position, as shown in Figure 1, by a conducting bridging member 1 reciprocally operated in a vertical direction by an insulating lift rod 8. The lift rod 8 is actuated by suitable mechanism, not shown, but which is responsive to either manual operation or to the existence of excessive currents carried by the circuit to cause reciprocal motion of the lift rod 8 to effect opening and closing of the interrupter.

Referring to Fig. 2, which more clearly shows the internal construction of the arc-extinguishing assemblage 6, it will be observed that the extinguishing assemblage 3 includes a low current arc-extinguishing'unit, generally designated by the reference numeral 9 disposed in parallel with a high current arc-extinguishing unit generally designated by the reference numeral l0. Suitable contact structure is employed in the high current unit 10 to effect the establishment of a pressure-generating arc II and an interrupting are 12 as more clearly shown in Fig. 5. More specifically, such contact structure includes an upper movable pressure-generating contact l3 cooperable with a relatively stationary intermediate contact l4 to establish the pressure-generating arc H. A lower movable interrupting contact l6 cooperates with the intermediate contact I4 to establish the interrupting are 12.

In this embodiment of my invention, I employ a hydraulic operating mechanism or means generally designated by the reference numeral l1 to effect both the opening of the contact structure and also the desired flow of oil through the low current unit 9. It will be observed that the pressure-generating contact I3 has an operating piston l8 secured to its upper end and movable within an operating cylinder l9, the piston l8 being spring-biased to the closed, circuit position, as shown in Fig. 2, by a compression closing spring The lower end of the spring 20 seats upon the piston l8 and the upper end of the spring 20 seats against a plate 2| embedded in a recess 22 formed in a casting member 23. The casting member 23 is secured by insulating bolts, not shown, to an insulating plate I01. The latter is secured by insulating means to a contact foot 11 threadedly secured and clamped by a bolt 24 to the terminal stud 25 which passes interiorly through the terminal bushing 5.

The lower movable interrupting contact l6 likewise has an operating piston 26 secured to its lower end which is movable within an operating cylinder 21 and biased to its upper closed circuit postion by a compression closing spring 28. The lower end of the compression spring 28 seats upon a suitably inwardly extending flange portion 29 integrally formed with the operating cylinder 21. The upper end of the cylinder 21 has a horizontally extending flange portion 30 which abuts against the upper edge of a pump cylinder designated by the reference numeral 3|.

Movable within the pump cylinder 3| is a pumping piston 32. the latter being biased downwardly in the pumping direction by a pump spring 33. The pumping piston 32 has a depending cylindrical portion 34 which in the closed circuit position of the interrupter, as shown in Fig. 2, makes abutting engagement with the extremity 35 of the'bridglng member 1.

The pressure-generating arc ll (Fig. 5) is established within a pressure-generating chamber generally designated by the reference numeral 36 in Fig. 2. The interrupting arc I2 (Fig. 5) is established within an interrupting chamber generally designated by the reference numeral 31 and formed by the superpositioning of a plurality of suitably configured insulating plate members. More specifically, the plate members form a multi-oriflce interrupting structure adjacent to the path of movement of the interrupting arc l2.

The plate structure is formed of three different types of plates. The first type is herein called an insulating inlet plate and is designated by the reference numeral 38 in Fig. 4. It will be noted that the insulating inlet plate 38 has two cutout portions 39 formed therein which are interconnected by inlet passages 40.

On opposite sides of the inlet plate 38 are disposed a pair of insulating orifice plates desig: nated by the reference numeral 4| and shown more clearly in Fig. 4. The orifice plates 4! have the cutout portions 39 formed therein and, in addition to the plates 38, have apertures 42 provided therein through which extend insulating tie rods 43 which serve to hold the plate structure fixedly in position. Furthermore the

plates

38, 41 have cutout portions 44 provided therein, the purpose for which will appear more clearly hereinafter.

The insulating orifice plate M has an orifice 45 formed therein through which the movable interrupting contact it passes to draw the interrupting arc l2 therethrough.

The third type of insulating plate used in the interrupting chamber 31 is a composite vent plate generally designated by the reference numeral 46. The composite vent plate 46 consists of two

insulating halves

41, 48 laterally spaced apart to form opposite vent passages 49 leading out of the assemblage 6 away from the interrupting chamber 31. The insulating half 41 has apertures 42 provided therein for the reception of the tie rods 43. The insulating half 41 also has the cutout portion 39 provided therein.

The insulating half 48 has the cutout portion 39 formed therein and also has the apertures 42 provided therein through which extend the in sulating tie rods 43. Also the plate 48 has the cutout portion 44 provided therein.

The cutout portions 39 provided in the several insulating plates align to form vertical flow passages generally designated by the reference numeral 50 and interconnecting the pressure-gengratin'g chamber 36 with the interrupting chamer 3 From the above description, it will be apparent that upon opposite movement of the contacts l3, l6 away from the relatively stationary intermediate contact l4 there will be formed the pressure-generating are H within the pressure-generatlng chamber 36 and the interrupting arc 12 within the interrupting chamber 31, as more clearly shown in Fig. 5.

Fluid, in this instance oil, under pressure from the pressure-generating arc llwill flow downwardly through the two vertical flow passages 58 into the interrupting chamber 31 through the plurality of inlet passages 46, to strike the interrupting arc I2 radially thereof.

The oil will then be compelled to fiow longitudinally of the interrupting arc |2 through the orifices 45 provided by the several insulating orifice plates 4| to vent out of the high current unit l6 through the oppositely disposed vent passages 49 as provided by the several vent plates 46. Interruption of the interrupting arc I2 soon follows by such effective deionizing conditions and the circuit passing through the contacts I3, l4, I6 is thereby interrupted.

The interrupting plate structure is set forth and claimed in United States patent application, Serial Number 465,244, filed November 11, 1942, now U. S. Patent 2,406,469, issued August 27, 1946, and assigned to the assignee of the instant application.

It will be noted that upon the opening downward motion of the extremity 35 of the member 1, the pump spring 33 will be permitted to force the pumping piston 32 downwardly to thereby cause a flow of fluid, in this instance oil, to pass out of the pump cylinder 3|, as shown by the arrows in Fig. 2, through one or more apertures provided in the pump cylinder 3| to flow upwardly through a passage 52 provided by a casting member 53, integrally formed with cylinder 3|, to flow through a passage 54 to the top side of the operating piston 26 and also upwardly through a conduit 55 (as provided by the alignment of the several cutout portions 44 provided in the plate structure) to act upon the lower surface of the operatin piston I8.

Thus the operating liquid will serve during the opening operation to force by hydraulic action upward movement of the piston l8 and contact l3 against the biasing action exerted by the closing spring 20, and downward opening motion of the piston 26 and contact |6 against the upward biasing action exerted by the closing spring 28. The result is a simultaneous movement of the contacts l3, l6 away from the intermediate stationary contact H to practically simultaneously establish the pressure-generating are H and the interrupting arc l2 within the high current are extinguishing unit ll) of the assemblage 6.

Immediately adjacent to the high current interrupting unit In is the low current interrupting unit 9, which will now be described. This unit 9 consists of a first movable selective current responsive contact 59 having secured thereto at its upper end an armature 66 which is actuated by a current responsive mechanism generally designated by the reference numeral 6|, and including a series coil 62 disposed in a suitable magnetic structure 63. Upon the passage of current of predetermined magnitude through the series coil 62, the electromagnetic force will cause upward opening movement of the armature'66 and first movable selective contact 59 away from an intermediate contact structure generally designated by the reference numeral 64.

The intermediate contact structure 64 includes an upstanding stationary contact 65, which in the closed circuit position of the interrupter, as shown in Fig. 2, makes abutting contacting engagement with the selective contact 69. The lower portion of the intermediate contact structure 64 includes a cup-shaped portion 66, within which are disposed a plurality of contact segments 61 biased inwardly by the resiliency thereof and into contacting engagement with a lower second movable contact 68 of the unit 9. The second movable contact 66 has secured thereto at its lower end an operating piston 66 movable within an operating cylinder 16, in this instance formed as an integral portion of the casting member 53. Preferably a slider contact 1| is provided furnishing electrical contact between the contact 68 and the casting 53. A closing compression spring 12 is provided which biases the piston 69 and contact 68 upwardly toward their closed circuit position.

It will be observed that in the low current interrupting unit 9 there is provided a contact overlap designated by the length of arrow A. Thus the movable contact 66 must move downwardly a predetermined distance equal to the length of the qmtact overlap distance A before it is permitted tos arate from the contact segments 61 to draw an arc in the low current unit 9. The purpose of th= contact overlap distance A will be more fully apparent hereinafter.

The interrupting portion 16 of the low current unit 9 is formed by the superpositioning of a plurality of insulating plates which form the same type of multi-orifice interrupting structure adjacent the are drawn between the contacts 6T, 68 as was provided in the interrupting chamber 31 of the high current unit ID of the assemblage 6. The plate members are considerably smaller than those used in the interrupting chamber 31 to more effectively direct the oil flow adjacent the smaller size arc, but their general configuration is the same. Consequently since the plate members are merely smaller and have the same type of interrupting structure as was described formerly, they have been used with the same reference numeral but with the suffix A. Since the interrupting plate structure for the interrupting chamber 31 was previously specifically described, it is not believed to be necessary to repeat the aforesaid description for the interrupting portion 16 of the low current unit 9.

In the closed circuit position of the interrupter as shown in Figs. 1 and 2, the electrical circuit therethrough includes terminal stud 25, contact foot 11, conducting strap 18, series coil 62, conducting strap 19, casting member 23. The electrical circuit then has two parallel paths through the two electrical parallel disposed units 9, ill to the lower depending portion 34.

More specifically, the path through the high current unit I6 includes the piston l8, contact |3, contact l4, contact l6, piston 26, flexible shunt to the operating cylinder 21 and hence to the depending portion 34.

Also the current can pass through the parallel disposed low current unit 9, as by means of the casting 23, flexible conductor 8|, movable selective contact 59, stationary contact 65, cup-shaped portion 66, contact segments 61, lower movable contact 68, slider contact 1| to the casting member 53. The circuit extends from the casting member 53 through the conducting depending portion 34 to the bridging member 1, and through the other arc-extinguishing assemblage 6 of the interrupter (Fig. 1). The electrical circuit then extends in parallel paths through the left hand assemblage 6 in an identical manner to its passage through the right hand assemblage 6, to the left hand terminal stud 25 of the interrupter.

During the opening operation, suitable mechanism not disclosed, but which is responsive to either manual operation or to the existence of excessive current conditions existing in the electrical circuit controlled by the interrupter, causes downward opening motion of the lift rod 6. The downward motion of the lift rod 6 causes corresponding downward opening motion of the bridging member I.

Considering only the right hand assemblage 9, as shown in Fig.2, and assuming the existence of relatively high current conditions in the circuit controlled by the interrupter, the contact mechanism for the assemblage 6 will immediately function to cause upward opening motion of the movable current responsive contact 59 as caused by operation of the current responsive mechanism 9 I. This is shown in Fig. 5.

The downward motion of the extremity 35 of the bridging member 1 permits the pump spring 33 to force the pumping piston 32 downwardly to force oil under pressure out of the pump cylinder 3| to flow out of the one or more apertures 51. This oil flows upwardly through the passage 52 and on the top side of the piston 26 secured to the lower movable interrupting contact ii of the high current unit In. The oil also flows upwardly through the conduit 55 to act upwardly against the piston l8 to cause upward motion of the movable pressure-generating contact I 3 f the high current unit I 0.

Furthermore, the oil acts on the top surface of the operating piston 69 to force it downwardly within the operating cylinder III to thereby cause separation of the contacts 61, 58 after the contact 58 has travelled the predetermined contact overlap distance A.

It will be observed that the electromagentic selective mechanism 5| will immediately function before any downward motion of the lift rod 8. This is so because the coil 62 is constantly in series circuit and is immediately responsive to any overload condition existing in the circuit in the same manner as are the overload relays which cause functioning of the mechanism which causes downward opening motion of the lift rod 8. Thus upon high current conditions existing in the circuit controlled by the interrupter, the selective mechanism device 6| will immediately (without any delay) operate to separate the movable selective control 59 from the stationary contact 65. This will cause the current path to extend through the high current unit and not through the low current unit 9, the circuit through the latter being opened by the separation of the

contacts

59, 55 as shown in Fig. 5.

Thereafter, the hydraulic operating mechanism I1 functions to cause opposite movement of the contacts l3, IS in the high current unit I!) and also downward movement of the movable contact 69 in the low current unit 9. The opening of the contact structure within the high current unit l0 will cause interruption of the high amperage current therein as indicated in Fig. 5. There will be no arcing whatsoever within the low current unit 9 during high current interrupting operations.

Fig. 6 shows the contact travel of the movable contact 68 in the low current unit 9 as a function of time. It will be remembered that the contact 69 is hydraulically operated and is relatively light in construction. The contact 68 begins its opening movement from rest with a relatively low speed as indicated by the low initial slope of the curve. At time T the contact 68 has just completed the contact overlap distance A, and at this point begins its separation from the stationary contact segments 61.

During relatively high current interruption, the initial separation of the

contacts

59, 55 causes the circuit to pass through the high current unit Ill. Because of the gap between the

contacts

59, 65 of the low current unit 9, arcing is initiated in the high current unit l0. Because of the highspeed operation of the contact 69, after its initial slow speed, as represented by'the curve of Fig. 6, the

sum of the two contact gaps in the low current unit 9 is greater than those of the high current unit Ill. The contact 98 is relatively light in con-' struction and moves faster than the contacts l3 or 16 of the high current unit. Since the summation of the contact gaps of the low current unit 9 is always greater than the summation of the contact gaps of the high current unit l0 during high current interruption because of the high speed of the relatively light contact 68, when interruption finally does occur in the high current unit Iii, there will be no restriking in the low current unit 9 since at this time there will be a greater total gap distance in the low current unit 9 than that which exists at the time of interruption in the high current unit I9. Thus when the gap distances in the high current unit are sufficient to effect interruption, the interruption process will be completed and the circuit will be finally interrupted.

After the high current circuit has been interrupted within the high current unit lo, the pumping piston 32 will cease its downward following travel with the bridging member I by striking the lower plate portion 82 of the casting 53 to terminate the downward opening movement of the pumping piston 32. When this occurs the extremity 35 of the bridging member I will separate downwardly away from the depending cylindrical portion 34 to insert an isolating gap into the circuit.

In the fully open circuit position of the interrupter, the several closing springs 20, 28, and I2 will function to close the contact structure within the units 9, l0, leakage occurring around the several pistons f8, 26 and 69. Also a closing spring 83 associated with the electromagnetic selective mechanism Bl will cause downward closing motion of both the armature 60 and movable selective contact 59. Consequently in the fully open circuit position of the interrupter, the entire contact structure within the assemblage 6 is completely closed, as is the condition shown in the closed circuit position of the interrupter of Fig. 2. The only difference is that in the fully open circuit position of the interrupter, the bridging member I has moved downwardly to its fully open circuit position inserting two isolating gaps in series and permitting a complete contact closure of assemblage 6, as shown in Fig. 2.

Assuming the existence of relatively low cur-, rent conditions in the circuit controlled by the interrupter, the current responsive device 5| will not function at all, and hence the

contacts

59, 65 of the low current unit 9 will remain in contacting engagement. This is shown in Fig. 3.

Since there is a contact overlap distance equal to A, which must be traversed by the movable contact 68 of the low current unit 9 before there is any contact separation in the low current unit 9, the contact gaps will hence first occur in the high current unit III. The circuit is then only completed through the low current unit 9, and arcing will first be initiated in the low current unit 9 between the

contacts

61, 68 to draw an arc 51 (Fig. 3).

In other words, during the time T while the

contacts

61, 68 are still in engagement, there will be separation occurring between the contacts in the high current unit I0, to force the electrical circuit through the low current unit 9.

Deionization of the low current arc 51 will occur in the low current unit 9 by a flow of fluid, in this instance oil, pumped by the pumping piston 92 through the multi-orifice interrupting portion I5 of the low current unit 9, and circuit interruption follows.

It is to be noted that because of the failure of the current responsive device 6| to operate during low currents, and because of the predetermined contact overlap distance A, the summation of the contact gaps in the high current unit I will at all times during the interruption process be greater than the gap distance between the

contacts

61, 50 in the low current unit 9. When interruption of the arc 51 finally does occur in the low current unit 9, the circuit will, at this time, be finally interrupted, because at this time of arc extinction the gap distances provided by the contact structure in the high current unit I0 is greater than that afforded by the contact gap at the time of interruption between the

contacts

61, 50.

After the arc extinction during low current interruption, the bridging member I inserts two isolating gaps in the circuit, and the contact structure recloses in the manner previously described.

There may be an intermediate range of current values in which operation of the current responsive device BI may be sluggish so it will not be definite in which interrupting unit the arcing will be initiated. Thus, the operation of the device will be so rapid at high current values that interruption in the high current unit I0 is always assured. Then, also, at low values of current the device 5| will not operate at all. But both interrupting units 9, I0 are each capable of interrupting satisfactorily currents in the intermediate range in which operation of the current responsive device GI may be sluggish.

The foregoing description referred to an assemblage 6 which was operated hydraulically and in which during the closing operation the circuit was completed exteriorly of the assemblage 6 so as not to contaminate the gaps within the units 9, I0 with any prestriking. This term means striking of the arc during the closing operation as the nearing contacts approach one another during the closing operation with voltage on the line. Since high voltage may exist on the line, there will be flash-over between the approaching contacts during the closing operation, even before they have actually contacted one another in abutting engagement.

Referring to Figs. 7 10, it will be apparent that I have provided a mechanically actuated type of assemblage 90 as contrasted with a hydraulically actuated assemblage 8 heretofore described. The plate structure for the high current unit I0 is exactly the same as that described hereinbefore; consequently, a further description thereof is not deemed necessary. Also, the construction of the low current unit 9 is the same as previously described, and therefore a specific description thereof is unnecessary. It will be observed that I have provided in this embodiment of my invention a pivotally mounted pressuregenerating contact 9I, pivotally mounted at 92 to the modified casting member 93. An insulating operating rod 90 is pivotally mounted by a pin and slot connection 95 to two externally extended actuating arms 96, only one of which is shown in Fig. 7, which are preferably integrally formed with the contact lever 9I. The operating rod 94 has an upwardly extending push rod portion 91 extending within a pump cylinder 98, in this instance, integrally formed with the casting member 93. A freely moving pump piston 99 makes separable abutting engagement with the upper end of the push rod portion 91 of the operating rod 94. The lower end of the operating rod 94 makes separable abutting engagement with the extremity 35 of the bridging member I only near the end of the closing stroke and during the initial portion of the opening stroke.

A flexible conductor I00 electrically interconnects the pivotally mounted pressure-generating contact 9I with the casting member 93. It will be noted that the casting member 99 is insulated from the contact foot 11 by an insulating plate IOI, as was the case in Fig. 2, so that the ele ctrical circuit may pass entirely through the strap I0 and series coil 62 of the electromagnetic selective mechanism 6 I.

A pair of brackets I02 are secured to the lower plate I03 of the assemblage 90 to pivotally support at I04 a contact arm I05 having pivotally connected thereto by a pin and slot connection I00, the movable contact 60 of the low current unit 9.

The contact arm I05 has a cup-shaped spring seat I01 pivotally secured thereto at I00 to serve as a lower seat for a compression spring I09, the upper end of which seats against the lower plate I03 of the assemblage 90.

In this modification, the interrupting contact IIO of the high current unit I0 is fixedly secured by a threaded connection to the bridging member I so as to move therewith. Fixedly secured to the side of the movable interrupting contact IIO is an actuating lug II I which makes separable abutting engagement with the spring seat I01 during the closing operation to cause upward closing movement of the contact 58 of the low current unit 9.

An armature 50 of the selective mechanism 6| has an upstanding rod portion I I2 having a. slot H3 formed therein through which passes a pin I I4 guided thereby, the pin I I4 being secured to the right hand extremity of an actuating lever I I5 pivotally mounted at I I6 to the casting member 99. The left-hand end of the actuating lever I I5 is pivotally connected at to the operating rod 94.

From the foregoing description, it will be apparent that in the closed circuit position of the interrupter, as shown in Fig. 7, the electrical circuit therethrough includes terminal stud 25, contact foot 11, strap I8, series coil 52, strap 19, to the casting member 93. The circuit then extends through two parallel paths through the parallel disposed units 9, I0 to the contact IIO, which is affixed to the conducting bridging member I. More specifically, the electrical path through the high current unit I0 includes the flexible conductor I00, pressure-generating contact 9|, intermediate contact I4 to the lower movable interrupting contact I I 0. The other parallel electrical path which extends through the low current unit 9 includes flexible conductor 8 I, upper rod portion II 2, armature 80, movable selective contact 59, stationary contact 65 of the intermediate contact structure 54. The circuit then extends through the contact segments 61, through movable contact 58 and thence through the conducting contact arm I05.

The circuit then extends through a flexible conductor 9 to the conducting bracket I02 and other assemblage 90, not shown, through which the circuit passes in an identical manner to the right-hand terminal stud 25 of the interrupter.

During the opening operation, assuming the existence of relatively high currents to be interrupted, the selective mechanism 6| will immediately function, as shown in Fig. 10, to cause upward motion of the movable selective contact 59 away from the stationary contact 55. This causes the electrical circuit to pass through the high current unit 10 and to be interrupted therein.

The high current carried by the circuit controlled by the interrupterwill cause the actuation of suitable relay mechanism to cause actuation of the operating mechanism, not shown, which drives the insulating lift rod 8 in a downward circuit opening direction. The downward opening movement of the lift rod 8. causes corresponding downward opening movement of the conducting bridging member 'I and the lower movable interrupting contacts I I secured fixedly thereto. The downward motion of the bridging member I permits the compression spring l2l to force both the pump piston 99 and the operating rod 94 downwardly. The downward motion of the pump piston 99 forces fluid, in this instance oil, under pressure downwardly within the pump cylinder 98 and through a conduit I22 to the low current unit 9 where the oil under pressure passes through the multi-oriflce interrupting structure 16 adjacent the path of movement of the movable contact 58 in a manner as previously described.

The compression spring l2l also forces the operating rod 94 downwardly as permitted by downward motion of the bridging member 1. The downward opening movement of the operating rod 94 causes counterclockwise opening rotative motion of the pressure-generating contact 9| to cause the separation thereof upwardly away from the intermediate contact M. This draws a pressure-generating are H, as more clearly shown in Fig. 10.

Since the lower movable interrupting contact H0 is fixedly secured to the bridging member I,

it moves therewith downwardly during the opening operation to separate downwardly away from the intermediate contact H to draw an interrupting arc l2, as more clearly shown in Fig. 10. Also, the downward motion of the actuating lug Ill permits the compression spring I09 to force the contact arm I05 downwardly to thereby cause downward opening movement of the movable contact 68 in the low current unit 9.

During the interruption of high amperage currents, as previously mentioned, there first occurs upward separating motion of the movable selective contact 59 to insert a gap in the low current unit 9 between

contacts

59 and 65. This opens the circuit through the low current unit 9 and forces the current to flow through the high current unit Ill. The downward motion of the bridging member I establishes practically simultaneously a pressure-generating are H and an interrupting are I! within the high current unit In as shown in Fig. 10.

As was the case with the hydraulic operating assemblage 6, the summation of the contact gaps in the low current unit 9 is greater at all times during the opening operation than the summation of the contact gaps in the high current unit ID, in which arcing is initiated and extinguished, In

this connection it will be noted that the lever arm distance to the movable contact 58 is over twice that for the contact llli, it being remembered that the spring seat maintains abutting relationship with the lug Ill movable with the contact H0. So the speed of opening of contact 58 is over twice that of contact I I0.

Once the contact separation in the high current unit I0 is suflicient to effect interruption, at

this same time the contact separation is greater in the low current unit 9 so the circuit will remain interrupted.

It will be observed that in the fully open circuit position of the interrupter that the pin Ill holds the armature 60 and movable selective contact 59 in their upper position. The reason for this is that during a closing operation it is more desirable to close the circuit through the high current unit In in which the contact structure is relatively heavy, than in the low current unit 9, where the contact structure is relatively light and not adapted for the carrying of currents of considerable magnitude. Thus, by having the pin H4 maintain the selective mechanism 6| in its open position in the fully open circuit position of the interrupter, during a subsequent closing operation the contacts 9|, M, NO, moving fast, will make engagement to complete the circuit in the unit l0, even before the movable selective contact 59 has lowered sufliciently to make contacting engagement with the stationary contact to thus close the circuit through the low current unit 9. Thus, the arrangement is operable to always close the circuit through the high current unit In and not through the low current unit 9 during a closing operation.

Assuming the existence of relatively low current in the circuit to be interrupted, the current responsive device 6| will not be actuated as shown in Fig, 9. Since the movable contact 68 must traverse. the predetermined contact overlap distance A before there is any contact gap distance in the low current unit 9, the contacts in the high current unit III will open during this time T and hence open the circuit through the high-current unit l0. Thus, the circuit is closed through the low current unit 9 and open in the high current unit NJ as shown in Fig. 9.

The construction is such that the summation of the contact gaps in the high current unit I!) is at all times greater during low current interruption than the gap distance between the

contacts

61, 68 in the low current unit 9. Thus, when the

contacts

61, 68 have separated a sufficient extent so that extinction of the low current are 51 in the low current unit 9 may take place, since at this same time the summation of the gap distances in the high current unit I ll is greater than the gap distance between the

contacts

61, 68, the circuit when interrupted in the low current unit 9 will remain open and no arc will restrike in the high current unit l0.

Deionization of the low current are in the low current unit takes place by the oil flow down the conduit I22 and through the multi-oriflce interrupting structure 16.

As before, there may be an intermediate range of current values in which operation of the current responsive device 6| may be sluggish, and it will not be certain in which interrupting unit interruption of the circuit will take place. But this is not important since either unit is capable of adequately interrupting the circuit in this intermediate circuit range.

During the closing operation, the bridging member 1 moves upwardly to thereby cause the entrance of the interrupting contact H into the arc-extinguishing unit 80, while at the same time the extremity engages the operating rod 94 to cause closure of the pressure-generating contact 9| against the. intermediate contact l4 and also to cause charging motion of the pumping piston 99. The spring "I is thereby compressed. Also, the actuating lu Ill movable with the interrupting contact llll strikes the spring seat lli'l to cause upward closing movement of the movable contact 88 in the low current unit 8.

It will be apparent from the foregoing description that I have provided an improved circuit interrupter in which the orifice size in each unit is such as to most effectively direct fluid flow adjacent the arc drawn into the orifice. I have employed a relatively large multi-orifice interrupting construction for interrupting relatively high currents, and I have utilized a relatively small bore multi-orifice interrupting construction to effect extinction of relatively low currents.

Furthermore, the constructions are such so that when arcing occurs in one unit the summation of the contact gaps in the other unit is always greater during the entire opening operation. The hydraulic construction is operable in a simple manner, having relatively few moving parts and permitting contact closure in the fully open circuit position of the interrupter. The mechanically actuated interrupter is operable to always close the circuit during a closing operation through the high current interrupting unit.

Thus, I have employed aninterruptlng construction particlarly adapted for the use of liquid flow in which interruption is brought about in the unit particularly adapted for the magnitude of current being interrupted.

Although I have shown and described specific constructions, it is to be clearly understood'that the same were merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter of the liquid blast type, an arc-extinguishing assemblage including electrically parallel arc-extinguishing units, one of the units being especially suitable for high current interruption, the other of the units being especially adaptable for low current interruption, contact means associated with the high current unit operable to establish a pressure-generating arc and a serially related interrupting arc, liquid flow passage means interconnecting the two arcs so liquid under pressure from the pressuregenerating arc may fiow under pressure toward the interrupting arc to effect the latters extinction, a current responsive mechanism, contact structure associated with the low currentunit including a movable selective contact cooperating with a relatively stationary contact and a second movable contact also cooperable with the relatively stationary contact, means providing a contact overlap distance between the said second movable contact and the relatively stationary contact, the current responsive mechanism causing the opening motion of the movable selective contact only during high current interruption, and a hydraulic operating mechanism for actuation of the contact means of the high current unit and also of the second movable contact of the low current unit.

, ,2. In a circuit interrupter of the liquid blast type, an arc-extinguishing assemblage includin electrically parallel arc-extinguishing units, one of the units being especially suitable for high current interruption. the other of the units being especially adaptable for low current interruption, contact means associated with the high current unit operable to establish a pressure-generating arc and a serially related interrupting arc, a multi-orifice interrupting structure disposed adjacent to the interrupting arc so that liquid under pressure from the pressure-generating arc may flow through the multl-orifice interrupting structure adjacent the interrupting arc to efi'e'ct the extinction of the latter, a current responsive mechanism, contact structure associated with the low current unit including a movable selective contact cooperating with a relatively stationary contact and a second movable contact also cooperable with the relatively stationary contact, means providing a contact overlap distance between the second movable contact and the relatively stationary contact, the current responsive mechanism causing the opening motion of the movable selective contact only during high current interruption, and a hydraulic operating mechanism for actuation of the contact means of the high current unit and also of the second movable contact of the low current unit.

3. In a circuit interrupter of the liquid blast type, an arc-extinguishing assemblage including electrically parallel arc-extinguishing units, one of the units being especially suitable for high current interruption, the other of the units being especially adaptable for low current interruption, contact means associated with the high current unit operable to establish a pressure-generating arc and a serially related interrupting arc, a multi-orifice interrupting structure disposed ad- Jacent to the interrupting arc so that liquid under pressure from the pressure-generating arc may flow through the multi-orifice interrupting structure adjacent the interrupting arc to efiect the extinction of the latter, a current responsive mechanism, contact structure associated with the low current unit including a movable selective contact cooperating with a relatively stationary contact and a second movable contact also cooperable with the relatively stationary contact, the current responsive mechanism causing the opening motion of the movable selective contact only during high current interruption, a hydraulic operating mechanism for actuation of the contact means of the high current unit and also of the second movable contact of the low current unit, means defining a muiti-orifice interrupting structure disposed adjacent the arc established between the second movable contact and the relatively stationary contact associated with the low current unit, and means whereby the hydraulic mechanism is operable to send liquid through the multi-orifice interrupting structure in the low current unit to effect the extinction of the are drawn therein during low current interruption.

4. In a circuit interrupter, an arc-extinguishing assemblage including two interrupting units in parallel one of which is especially adapted for high current interruption and the other of which is especially suited for low current interruption, contact means in the high current unit for establishing therein an arc, contact means associated with the low current unit including a movable selective contact, a relatively stationary contact and a second movable contact, means providing a contact overlap distance between the said second movable contact and the relatively stationary contact, and current responsive means for ensuring that the circuit will be interrupted only in the high current unit during high current interruption and in the low current unit during low current interruption, the current responsive means causing actuation of the movable selective contact only during high current interruption.

5. In a liquid break type of circuit interrupter, a high current unit connected in electrical parallel with a low current unit, contact structure associated with the high current unit including two oppositely movable contact members, a pair of operating pistons secured to the two contact members for causing opening of the same, a pair of operating cylinders within which the pair of operating pistons move, a pump cylinder, a pump piston movable within the pump cylinder, a member for charging the pump piston, biasing means for the pump piston, conduit means interconnecting the pump cylinder with the two operating cylinders so that opening motion of the pump piston will force operating liquid through the conduit means to effect opening of the pair of contact members, contact structure associated with the low current unit including a movable selective contact, a relatively stationary contact and a second movable contact, a current responsive mechanism for causing opening separating motion of the movable selective contact only during currents of predetermined large magni-.

tude, an operating piston secured to the second movable contact, an operating cylinder within which the last-mentioned operating piston moves, conduit means interconnecting the pump cylinder with the last-mentioned operating piston to cause opening of the second movable contact of the low current unit simultaneously with the movement of the pair of contact members, and means providing a predetermined contact overlap distance between the relatively stationary contact and the second movable contact of the low current unit.

6. In a liquid break type of circuit interrupter, a high current unit connected in electrical parallel with a low current unit, contact structure associated with the high current unit including two oppositely movable contact members, a pair of operating pistons secured to the two contact members for causing opening of the same, a pair of operating cylinders within which the pair of operating pistons move, a pump cylinder, a pump piston movable within the pump cylinder, a member for charging the pump piston, biasing means for the pump piston, conduit means interconnecting the pump cylinder with the two operating cylinders so that opening motion of the pump piston will force operating liquid through the conduit means to effect opening of the pair of contact members, contact structure associated with the low current unit including a movable selective contact, a relatively stationary contact and a second movable contact, a current responsive mechanism for causing opening separating motion of the movable selective contact only during currents of predetermined large magnitude, an operating piston secured to the second movable contact, an operating cylinder within which the last-mentioned operating piston moves, conduit means interconnecting the pump cylinder with the last-mentioned operating piston to cause opening of the second movable contact of the low current unit simultaneously with the movement of the pair of contact members, means defining a multi-orifice interrupting structure of relatively large bore within the high current unit, and means defining a multi-orifice interrupting structure of relatively small bore within the low current unit through which liquid from the lastmentioned conduit means may flow.

'7. In a liquid break type of circuit interrupter, a high current unit connected in electrical parallel with a low current unit, contact structure associated with the high current unit including two oppositely movable contact members, a pair of operating pistons secured to the two contact members for causing opening of the same, a pair of operating cylinders within which the pair of operating pistons move, a pump cylinder, 8. pump piston movable within the pump cylinder, a

member for charging the pump piston, biasing means for the pump piston, conduit means interconnecting the pump cylinder with the two operating cylinders so that opening motion of the pump piston will force operating liquid through the conduit means to effect opening of the pair of contact members, contact structure associated with the low current unit including a movable selective contact, a relatively stationary contact and a second movable contact, means providing a contact overlap distance between the said second movable contact and the relatively stationary contact, a current responsive mechanism for causing-opening separating motion of the movable selective contact only during currents of predetermined large magnitude, an operating piston secured to the second movable contact, an operating cylinder within which the last-mentioned operating piston moves, conduit means interconnecting the pump cylinder with the lastmentioned operating piston to cause opening of the second movable contact of the low current unit simultaneously with the movement of the pair of contact members, and biasing means for all the contact structure toward tho zlosed circuit position so that in the open circuit position of the interrupter the contacts associated with the high and low current units are completely closed.

8. In a circuit interrupter of the liquid break type, a high current unit including a pivotally mounted pressure-generating contact, a relatively stationary contact, and a movable interrupting contact, a movable member to which the movable interrupting contact is secured, an operating rod operatively connected to the pressure-generating contact and actuated by the movable member during the end of the closing operation, a low current unit in parallel with the high current unit and including a movable contact, means whereby motion of the movable member will cause movement of the movable contact of the low current unit, a movable selective contact cooperable with a relatively stationary contact, means providing a contact overlap distance between said movable contact of the low current unit and the relatively stationary contact, and a current responsive means for causing actuation of the movable selective contact associated with the low current unit only during high current interruption.

9. In a circuit interrupter of the liquid break type, a high current unit including a pivotally mounted pressure-generating contact, a relatively stationary contact and a movable interrupting contact, a movable member to which the movable interrupting contact is secured, an operating rod operatively connected to the pressure-generating contact and actuated by the movable member with the low current unit the movable member for forcing the contact arm to the closed position, a movable selective contact, and a current responsive means for causing actuation of the movable selective contact associated with the low current unit only during high current interruption.

10. In a circuit interrupter of the liquid break type, a high current unit including a pivotally mounted pressure-generating contact, a relatively stationary contact, and a movable interrupting contact, a movable member to which the movable interrupting contact is secured, an operating rod operatively connected to the pressure-generby the movable memating contact and actuated ber during the end of the closing operation, a low current unit in parallel with the high current unit and including a movable contact, means whereby motion of the movable member will cause movement of the movable contact of the low current unit, a movable selective contact, another relatively stationary contact, means providing a contact overlap distance between the movable contact associated with the low current unit and the said other relatively stationary contact, 1

a current responsive means for causing actuation of the movable selective contact associated only during high current interruption, and liquid flow moving means operated by the operating rod to effect extinction of the arc in the low current unit.

11. In a circuit interrupter oi the lifiuid break type, a high current unit including a pivotally mounted pressure-generating contact, a relative stationary contact, and a movable interrupting contact, a movable member to which the movable interrupting contact is secured, an operating rod operatively connected to the pressure-generating contact and actuated by the movable member during the end of the closing operation, a low current unit in parallel with the high current unit and including a movable contact and another relatively stationary contact, means where by motion of the movable member will cause movement of the movable contact of the low current unit, a movable selective contact cooperable with said other relativelystationary contact, a current responsive means for causing actuation of the movable selective contact associated with the low current unit only during high current interruption, means causing the openingof the movable selective contact in the fully open circuit position of the interrupter, and means de laying the closing of the movable selective contact during the closing operation until complete closure of the contacts associated with the high current unit.

12. In a liquid break type of circuit interrupter, an arc-extenguishing assemblage including two interrupting units in parallel one of which is especially adapted for high current interruption and the other of which is especially suited for low current interruption, contact means in the high current unit for establishing therein an arc, contact means associated with the low current unit including a movable selective contact, a relatively stationary contact and a second movable contact, means providing a contact overlap distance between the second movable contact and the relatively stationary contact of the low ourthe current responsive means causing actuation of the movable selective contact only during high current interruption. 7

13. In a liquid break type of circuit interrupter, an arc-extinguishing assemblage including two interrupting units in electrical parallel one of which is especially adapted for high current interruption and the other 01' which is especially suited for low current interruption, contact means in the high current unit for establishing arcing therein, a current responsive mechanism, contact structure associated with the low current unit including a movable selective contact actuated to the open position by operation orthe current responsive mechanism during high current interruption and also including a pair of separable contacts connected in series with the aforesaid movable selective contact, and means providing a, contact overlap distance between the pair of separable contacts of predetermined amount.

14. In a liquid break type of circuit interrupter, an arc-extinguishing assemblage including two interrupting units in electrical parallel one of which is especially adapted for high current interruption and the other or which is especially suited for low current interruption, contact means in the high current unit for establishing therein a pressure-generating arc and a serially related interrupting arc, passage means for the liquid under pressure from the pressure-generating arc to flow toward the interrupting arc to effect the latters extinction, a current responsive mechanism, contact structure associated with the low current unit including a movable selective contact actuated to the open position by operation of the current responsive mechanism during high current interruption and also including a pair of separable contacts connected in series with the aforesaid movable selective contact, and means providing a contact overlap distance between the pair of separable contacts of predetermined amount.

15. In a liquid break type of circuit interrupter, an arc-extinguishing assemblage including two interrupting units in electrical parallel one of which is especially adapted for high current interruption and the other of which is especially suited for low current interruption, contact means in the high current unit for establishing arcing therein, a current responsive mechanism, contact structure associated with the low current unit including a movable selective contact actuated to the open position by operation of the current responsive mechanism during high current interruption and also including a pair of separable contacts connected in series with the aforesaid movable selective contact, and means for causing the summation of the arcing distance in each unit to be greater during the interruption process than that in the other unit when arcing is initiated in the other unit.

16. In a liquid break type of circuit interrupter, an arc-extinguishing assemblage including two interrupting units in parallel one of which is especially adapted for high current interruption and the other of which is especially suited for low current interruption, contact means in the high current unit 'for establishing therein a pressuregenerating arc and a serially related interrupting arc, passage means for the liquid under pressure from the pressure-generating arc to flow toward the interrupting arc to efiect the latters extinction, a current responsive mechanism, contact structure associated with the low current unit including a movable selective contact actuated to the open position by operation of the current responsive mechanism during high current interruption and also including a pair of separable contacts connected in series with the aforesaid movable selective contact, and means for causing the summation of the arcing distance in each unit to be greater during the interruption process than that in the other unit when arcing'is initiated in the other unit.

17. In a circuit interrupter, an arc-extinguishing assemblage including two interrupting units in electrical parallel one of which is especially adapted for high current interruption and the other of which is especially suited for low current interruption, contact means in the high current unit for establishing arcing therein, an operating mechanism for actuating the contact means in the high current unit, a current responsive device, contact structure associated with the low current unit including a movable selective contact and contact means including a pair of separable contacts serially related to the movable selective contact, a contact overlap distance between said last-mentioned pair of separable contacts, the

current responsive device causing the opening motion of the movable selective contact during the interruption of currents of predetermined high value, and the operating mechanism also causing the opening motion of the contact means associated with the low current unit.

18. In a circuit interrupter, an arc-extinguishing assemblage including two interrupting units in electrical parallel one of which is especially adapted for high current interruption and the other of which is especially suited for low current interruption, contact means in the high current unit for establishing arcing therein, an operating mechanism for actuating the contact means in the high current unit, a current responsive device, contact structure associated with the low current unit including a movable selective contact and contact means including a pair of separable contacts serially related to the movable selective contact, the current responsive device causing the opening motion of the movable selective contact during the interruption of currents of predetermined high value, the operating mechanism also causing the opening motion of the contact means associated with the low current unit, and means for causing the summation of the arcing distance in each unit to be greater during the interruption process than that in the other unit when arcing is initiated in the other unit.

FRANCIS J. FRY.

nnramanoas crew The following references are of record in the file of this patent:

UNITED STATES PATENTS