US2470628A - Circuit interrupter - Google Patents

Description

y 1949. R. LUDWIG mm. 2,470,628

CIRCUIT INTERRUPTER Filed May 24, 1944 2 Sheets-Sheet l &

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W/KM KW /W Patented May 17, 1949 Leon R. Ludwig,

Wilkinsburg, Herbert J. Webb,

Forest Hills, and Benjamin P. Baker, Turtle Creek, Pa., Corporation,

assignors to Westinghouse Electric East Pittsburgh, Pa., a'corporation of Pennsylvania Application May 24, 1944, Serial No. 537,074 11 Claims. (01. 200-148) resistors or impedance means which shunt the main interrupting gaps.

Another object is to provide an improved circuit interrupter of the fluid blast type in which the sequence of opening the several gaps is provided in an improved manner.

Another object is to more effectively control the distribution of voltage above and below an orifice through which an arc is drawn to be interrupted.

Another object is to provide an improved circuit interrupter having a shunting resistor in parallel with the main interrupting gap and to utilize the fluid blast employed to interrupt the residual current through the shuntin resistor to also operate a conservator which prevents further escape of fluid to the atmosphere following interruption of the main arc and which also maintains a high pressure adjacent the main orifice to thereby maintain a high dielectric strength thereat to minimize the possibility of iestriking.

Another object is to provide an improved interlocking valve which prevents the application of closing air to close the disconnect contacts until the voltage is removed from the interrupting I gaps by the reclosure of the main contacts.

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

Figure 1 is a perspective view of a complete circuit interrupter embodying our invention and shown in the closed circuit position;

'Fig. 2 is an enlarged view in verifical cross-section of the left-hand half of the pole unit, it being understood that the right-hand half is of the same construction;

Fig. 3 is a sectional view taken along the line I II[III of Fig. 2; and

Fig. 4 is a fragmentary schematic view showing a portion of the operating arrangement.

fingers biased radially Referring to the drawings and more particularly to Fig.1 the reference numerals l, 2 and 3 designate hollow insulator columns supported on a base structure 4, the latter enclosing suitable operating equipment. The hollow insulators I, 2 and 3 support a housing 5 composed of a conducting material, the latter in turn supporting two additional insulatin columns 5 and 1. Dis-- connect contacts 8, 9 may be retracted into the housing 5 at the completion of an opening operation.

Referring more particularly to Fig. 2 it will be observed that the left-hand hollow insulator column 6 has an annular insulating plate l0 supported at its upper end which provides an orifice ll defined by an annular ring I2 of conducting material. The plate i0 supports a second annular insulating plate l3, the latter in turn supporting a conducting cylindrical member I4 having integrally formed therewith a spider member I5 and having exhaust apertures IS. The spider member l5 supports the stationary contact l1 which is preferably of the type havin segmental inwardly and serving to make engagement with a movable tubular main contact member i8.

Slidable within the conducting cylindrical member l4 and serving tocontrol the exhaust apertures I6 is a conservator is biased downwardly by compression springs 20. The compression springs 20 seat at their upper ends against a conducting cap member 2i, the latter secured by bolts 22 to the cylindrical member H. A Weather-proof cylindrical member 23 may be depended from the cap member 2i to prevent rain or snow from entering the exhaust apertures I 6. The movable main contact l8 makes sliding contact at 24 with segmental fingers 25, the latter being secured toan outer conducting tube 26 the lower end of which is supported by a cylindrical member 27 composed of a conducting material.

Threadedly secured to the lower end of the movable main contact l8 and operative within the cylindrical member 21 is a piston 28 biased upwardly by a compression spring 29. After the piston has moved down past the point 30 it uncovers by-passing channels 3| which lead to a conduit 32 by means not shown, except schematically in Fig. 4, which is hereinafter described. Bumper 33 supported on aplurality of resilient insulating washer members 34 is provided to cushion the end of the downward stroke of the piston 28. The cylindrical member 21 is threadedly secured at 35 to a casting member 36 through which passes a rod 31. The rod 31 is slidable through an aperture provided at the lower end of the tubular main contact member l8 and has a nut 38 threadedly secured to its upper end. Apertures 39 are provided at the lower end of the tubular contact l8 adjacent to the aperturethrough which the rod 31 is slidable. At the lower end of the rod 31 is a cylindrical valve 46 biased downwardly by a compression spring 4| and servin to control openings 42, 43 and 44. The opening 42 leads to atmosphere; the opening 43 leads to the tube 45 (Fig. 4), the latter conducting the closing air of the interrupter. The opening 44 leads 'to the left-hand end of the disconnect operating cylinder 46 (Fig. 4).

The conduit 32 connects with a dump valve generally designated by the reference numeral 41 by means of a conduit 49. The conduit 32 also leads by means of a conduit49 to the righthand end of the disconnect operating cylinder 46. The conduit 32 furthermore connects with a conduit 50 which leads at its right-hand end (Fig. 2) to the hollow insulator 1. The hollow insulator 1 contains concentrically positioned therein a resistor tube having at its upper end a stationary contact 52. Making engagement with the stationary contact 52 is a tubular movable contact 53 having secured thereto at its upper end a piston 54 biased downwardly by a compression spring 55.. The piston 54 is movable within a cylindrical member 56 having an aperture 51 at its upper end. The aperture 51 communicates with a tube 58 which leads to a pipe 59, the latter communicating with the region 66 above the conservator I9.

For some applications, it is desirable to provide a resistor R. which has a portion 11 in parallel between the line terminal 6| and the ring The resistor R also has a portion 1': in parallel between the ring l2 and the casting member 36. The resistor R may be mounted within a third insulating column, if desired, for protection against the weather. For other applications the resistor R need not be used, or the part 1'1 may be used without the part 1': as hereinafter described.

The operation of the circuit interrupter will now be explained. In the closed circuit position of the interrupter, as shown in all the figures, the electrical circuit therethrough proceeds from the line 62 to the line terminal 6|, conducting cap member 2|, bolts 22, conducting cylindrical member I4, spider member l5, stationary contact l1, movable tubular main contact l8, segmental fingers 25, conducting tube 26, cy-

lindrical member 21, casting member 36, to one 7 terminal of and through the primary winding of a current transformer not shown, but which is enclosed within the hollow insulator column 3. The other terminal of the primary winding makes sliding contact at 63 to the disconnect contact 8.

The circuit passes through the right-hand half of the pole unit in an identical manner, to the line 64'.

It will be observed that there is a shunting circuit around the contacts l1, l8 by means of the circuit through the resistor 5| in the insulator column 1. This shunt circuit extends from the line terminal 6| through conducting cap member 2|, through conducting pipe 59, conducting tube 58, cylindrical member 65, cylindrical member 56, piston 54, tubular contact 53, stationary contact 52, resistor tube 5|, conducting stem 66 to housing 5. Thus there are two parallel paths for the 4 4 current to flow between the line 62 and the housing 5.

To open the circuit controlled by the circuit interrupter manual means may be operated, or the current transformer may trip on overloadan overload contactor and open a valve, not shown, admitting air to conduit 61, which arrangement is, not herein disclosed but which is of a type shown in a patent application filed May 24, 1944, Serial No. 537,075, by Leon R. Ludwig, Benjamin P. Baker, and James Cumming, now Patent No. 2,447,656, issued August 24, 1948, and which is assigned to the assignee of the instant application. By an actuation of the aforesaid means opening air is caused to pass through the conduit 61 (Fig. 4). The opening air passing through the conduit 61' also passes through conduit 68 to move a piston 69 movable within a piston chamber 10 of the dump valve 41. The air pressure acting through the conduit 69 moves the piston 69 against the biasing action of a compression spring 1| to the left closing the port 12 leading to atmosphere. Thus the movement to the left of piston 69 closes the communication of conduit 48 to atmosphere.

The opening blast air passes through a conduit 13 of the interior of the insulator column 6 where it acts through an aperture 14 (Fig. 2) provided in the cylindrical member 21 to act downwardly on the piston 28. The piston 28 is not moved downwardly by the air pressure to overcome the biasing action of the compression spring 29 until theaif is of a sufllcient pressure to efiect interruption of the are drawn between the contacts |1, I8. When, however, the air is of this predetermined pressure the piston 28 will be moved downwardly, compressing the compression spring 29 until finally the by-passing channels 3| are uncovered. The air will then pass through the by-passing channels 3|, to the conduit 32 leadingtoward both the disconnect cylinder 46 and the interior of the insulator column 1. 7

By the time that the air pressure acts through the conduit'50, through the insulator column 1. through the aperture 15 to move the piston 54 upwardly compressing the compression spring and drawing an are between the contacts 52, 53, the arc drawn between the contacts |1, |8 will have been extinguished.

The breaking of the are between the contacts l1, l8 forces the current to flow through the shunting resistor circuit within the column 1 to not only decrease the rate of rise of the'recovery voltage transient but also to lower the amplitude of the recovery transient. Furthermore, the current is greatly reduced in magnitude as a result of having to pass through the, resistor tube 5| tures l6 which were originally opened by the initial application of air through the orifice II when interrupting the are between the contacts l1 and I8. Consequently, the reclosure of the exhaust apertures l6 prevents further escape of gas through the apertures I6 to maintain high pressure in the space between the contacts without further waste of air. The result is more economical breaker performance.

By the time that the opening air, passing through the conduit 49 to the right-hand end of the disconnect cylinder 45, effects leftward movement of the disconnect piston Hi, the are carrying the residual current passing through the resistor 5| will have been interrupted. As a result the disconnect contacts 8 and 9 are not separated to provide an isolating gap in the electrical circuit until all the arcs are extinguished and the circuit has been interrupted except for the very small current through the resistor R, if it is used.

It will be noted that the region II below the orifice II is at high pressure and hence is of a high dielectric strength, whereas the region I8 above the orifice II is a region of initially low pressure .and consequently of low dielectric strength. This is assuiring the state of affairs after the conservator has been raised by the initial application of opening air and before the conservator has been closed over the exhaust openings It by the air passing through the pipe 59. Thus it is desirable to provide for an impressing of a lower proportion of the total voltage across the contact gap above the orifice than across the contact gap below the orifice I I. We accomplish this by tapping oil a small fraction, say of the total value of the resistance R designated 11, between the contact I! and the ring I 2, while a greater fraction, say of the resistor R, designated 1:, is shunted across the ring I2 and the lower segmental contacts 25. By the aforesaid means we control the division of voltage across the orifice I I to take advantage of the higher dielectric strength of the high pressure gas within the region 11.

For some applications it may be desirable to use only the portion n of resistor R and not to use either the portion T2 of R or resistor 5I and its associated contact structure 52, 53. In this event, the portion r1 would effect a rapid interruption of the are drawn between the stationary contact I1 and the movable contact I8, and the passage of the movable contact I8 below the ring. I2 would draw only a residual current are between the ring I2 and the movable contact I8. This residual current are drawn between the ring I2 and movable contact I8 would not only be of low amperage but would have a considerably improved power factor and hence would be easily extinguished by the blast of air passing through the orifice I I.

Following the opening of the disconnect contacts 8 and 9 and the closing of the valve supplying conduit 61, a gradual leakage of air past the conservator I9 and through various connections will tend to lower the pressure of air within the insulator column 5 and blast tube I3. Finally the pressure will be sufliciently low to permit the compression spring II to force the piston '59 within dump valve 41 to the right opening the exhaust port I2. The opening of the exhaust port I2 will dump the air from the interior of the resistor column I and from the right-hand side of the disconnect piston I6. The compression springs 29 in column 6, and 55 in resistor column I will thereby eifect reclosure of the contacts II, I8 and 52, 53. Thus after the disconnect contacts 8, 9 have separated to introduce an isolating gap into the circuit following interruption of the arcs, the separable contacts will then reclose to remove voltage across the contact gaps so that the entire voltage impressed across the interrupter will be impressed across the gap produced by the separation of the disconnect contacts 8 and 9.

disconnect cylinder 48.

The circuit interrupter is closed by closing air passing through the conduit I9 (Fig. 4). Fig. 4 schematically shows the operation of the valve 48 of Fig. 2. In other words, upon downward movement of the movable contact I8 the rod 31 will actuate the valve, generally designated by the reference numeral 8| in Fig. 4, to effect thereby a dumping of air from the left-hand end of the Thus an opening immediately following a closing of the interrupter will not be retarded by pressure of closing air contained within the left-hand end of the disconnect cylinder 46 retarding the leftward movement of the disconnect piston I6. In other words, referring to Fig. 2, it will be observed that upon downward movement of the movable contact II the compression spring 4| will force thecylindrical valve downwardly closing the opening 48 and permitting communication between the exhaust port 42 and the opening 44 leading to the left-hand end of disconnect cylinder 48.

It will also be observed from Fig. 2 that the downward movement of the cylindrical valve 40 permits atmospheric air to enter through the aperture 82 to maintain the region 83 within the casting member 36 at atmospheric pressure. Consequently, there may be some exhaust of air through the movable tubular contact I8 during the interruption of the are drawn between the contacts II and I8. This exhaust of are products through the movable tubular contact I8, through the apertures 39 and into the region 83 within casting member 36 at atmospheric pressure will facilitate the interruption of the are drawn between the contacts II, I8.

It will be observed that following the completion of the opening operation and after reclosure of the contacts I!, I8 and 52, 53 following actuation of the dump valve 41, that the contact actuated valve 8| will be actuated to permit communication between conduit 45, through the valve 8|. to the left-hand end of the disconnect cylinder 48. Thus the breaker may be closed by an application of the closing air through the valve 8I into the disconnect cylinder 46 to effect a closing movement to the right of disconnect piston I6 and a consequent reclosure of the disconnect contacts 8 and 9 to effect thereby a completion of the electrical circuit through the interrupter.

It will be observed that the two resistor tubes 5|, or other impedance means, associated with the two columns 5 also serve to balance the voltage division between the two series interrupter columns 8 during the interruption process. Thus each half of the pole unit is not required to interrupt more than half the voltage impressed across the entire interrupter. The shunting impedances also cause the circuit rate of rise of recovery voltage to be decreased and at the same time decreases the overshoot of the restored voltage, easing the interrupting duty on the main interrupters 5. It is also apparent that charging currents of low amperage values may more easily be interrupted, for reasons wellknown in the art.

By reclosing the arcing contacts with springs, the interrupters 6, I are short-circuited, and all the applied voltage is placed across the visible outside isolating gap.

An alternative arrangement for using the shunting impedances 5| would be to permanently connect them across the two pairs of main contacts II, I8. In this event after the arcs drawn between the contacts II, I8 were extinguished, the

residual current drawn by the two impedances Such an arrangement may be obtained by using the resistor R, omitting the tap connection 85 and also omitting resistor 5| with its associated contact structure 52, 53.

By varying the value of the resistor tubes 5| the voltage can be divided between the two halves ofv the interrupter in any desired manner during the interruption process.

Although we have shown and described specific structures 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 by those skilled in the art without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. In a circuit interrupter of the gas blast type, means defining an orifice, a stationary contact disposed above the orifice on the low pressure side thereof, a movable contact separable from the stationary contact and movable through the orifice to draw an arc therethrough into the high pressure side of the orifice, a conducting member disposed adjacent to the orifice, and impedance means constantly connected in parallel with the contacts and having a tap connection to the conducting member to control the division of recovery voltage after arc extinction between each of said contacts and said conducting member generally in accordance with the dielectric strength of the gaseous medium on the respective sides of said orifice.

2. In a gas blast circuit interrupter, an are 7 extinguishing assemblage comprising a main interrupting unit and a parallel connected impedance interrupting unit, means for drawing a main arc in the main interrupting unit, first gas blast means for extinguishing the main arc, means responsive to said first gas blast means for drawing a residual current are in the impedance interrupting unit after the extinguishing of the main are, second gas blast means for extinguishing the residual current arc, and means actuated by gas from the second gas blast means to limit escape of gas from the main interrupting unit.

{3. In a gas blast circuit interrupter, an arc extinguishing assemblage comprising a main interrupting unit and a parallel connected impedance interrupting unit, piston means operative at a predetermined pressurefor drawing a main arc in the main interrupting unit, means comprising a gas blast for extinguishing the main arc, and piston means operative by and in response to the creation of a predetermined blast pressure in said main interrupting unit for drawing a residual current are in the impedance interrupting unit after the extinguishing of the main arc.

4. In a circuit interrupter of the gas blast type, an arc extinguishing assemblage comprising a main interrupting unit and a parallel connected impedance interrupting unit, means defining an orifice in the main interrupting unit, contact means for drawing a main are through the orifice, means permitting the flow of -a gas blast through the orifice to extinguish the main arc, venting means on the exhaust side or the orifice, a conservator controlling the venting means, means directing gas to flow from said main interrupting unit through the impedance interrupting unit after extinction of the main arc to establish and extinguish a residual current are in said impedance interrupting unit, and means could be interrupted by the disconnect contacts 7 utilizing the exhaust gas from said impedance 1 terrupting unit to force the conservator to cl e the ventingxmeans.

v 5. In a gas blast circuit interrupter, an arc extinguishing assemblage comprising a main interrupting unit and a parallel connected impedance interrupting unit, contact means for drawing a main arc in the main interrupting unit, piston means for actuating the contact means, a by-passing channel uncovered by the piston means only after a predetermined contact separation to permit flow of gas to the impedance interrupting unit, contact means in the impedance interrupting unit for establishing an arc therein, means utilizing the flow of gas to the impedance interrupting unit for assisting extinction of the second-mentioned arc, and means employing gas entering theimpedance interrupting unit for limiting the escape of gas from the main interrupting unit.

6. In a gas blast circuit interrupter, an interrupting unit having gas blast directing means including an orifice, stationary contact means disposed on one side of the orifice, a movable contact separable from the stationary contact means and movable through the orifice to draw an are therethrough, a conducting member lining said orifice,

means for causing a blast of gas to fiow through said orifice to extinguish the arc, and impedance means connected between the stationary contact means and the conducting member and also between said conducting member and said movable contactto cause the recovery voltage on each side of said orifice following are extinction to divide generally in accordance with the dielectric strength of the gaseous medium on the respective sides of said orifice.

7. In a circuit interrupter, a pair of terminal members for connecting said interrupter in an electrical circuit, means defining an orifice, separable contact means connected between said terminal members, means for actuating said con tact means to open circuit position to establish an arc through said orifice, said contact means having a contact connected to each of said terminal members and disposed on each side of said orifice when said contact means are in the open circuit position, a conducting member adjacent said orifice, means for moving a blast of arc-extinguishing fiuid through said orifice to extinguish said are, and impedance means connected across said terminal members and having a tap connection to said conducting member for controlling the division of voltage from said orifice to each of said contacts following are extinction generally in accordance with the dielectric strength of the gaseous medium on each side of said orifice.

8. In a circuit interrupter of the gas blast type, a pair of relatively movable contacts operable to open and closed circuit position, means defining a gas passage surrounding said contacts, means positioned between said contacts when in the open circuit position obstructing said passage except for an orifice through which at least one of said contacts is movable to establish an arc, an annular conductor surrounding said orifice, means directing a blast of gas through said passage to extinguish said arc, said passage obstructing means causing a higher gas pressure to be maintained on the inlet side of said orifice than on the exhaust side thereof, impedance means connected across said contacts, and means connecting said annular conductor to an intermediate position along said impedance means to cause the recovery voltage appearing across said contacts after arc extinction to divide on either side of said orifice generally in accordance with the dielectric strength of the gaseous medium on the respective sides of said orifice.

9. A circuit interrupter of the gas blast type comprising a pair of relatively movable contacts for establishing an arc, gas blast passage means surrounding said contacts, means directing a blast of gas through said passage means to extinguish said arc, pressure responsive means operative to control the flow of exhaust gas from said passage means, said pressure responsive means being operative during arc extinction to permit the escape of gas from said passage means, a resistance connected in parallel with said contacts to limit the rate of rise of the circuit recovery voltage, a second pair of relatively movable contacts in series with said resistance for establishing a residual current are, a second gas blast passage means surrounding said second pair of contacts, and means responsive to the establishing of a gas blast of predetermined pressure in said first passage means for directing a portion of said gas from said first passage means to said second passage means to extinguish said residual current are, and means directing the exhaust gas from said second passage means to said pressure responsive means for causing the latter to prevent the further escape of gas from said first passage means.

10. A circuit interrupting structure comprising a first and second fluid passage means, contact structure including a first and second pair of separable contacts respectively disposed in said first and second fluid passage means, a resistance connected 'in series with said second pair oi separable contacts, the first pair of separable contacts being connected in shunt with said resistance and said second pair of separable conts, means for separating said first pair of contacts to establish an arc. means directing a blast of fluid through said first passage means to extinguish the arc and confine the circuit through said resistance and said second pair of contacts, a pressure responsive conservator associated with said first fluid passage mean for controlling the flow of exhaust gas therefrom, means for separating said second pair oi contacts to establish an arc, means directing a blast of fluid through said second fluid passage means to extinguish said last-named arc and finally interrupt the circuit,

and means rendering said conservator responsive; e pressure created by the exhaust fluid from to th said second fluid passage means to prevent the further escape or means,

fluid from said fluid passage 10 11. A circuit interrupter of the gas blast type comprising a pair of relatively movable contacts for establishing an arc, gas blast passage means of gas through said passage means to extinguish said arc, valve means responsive to pressure in both opening and closing directions for controlling the fiow of exhaust gas from said passage means, spring means biasing said valve means toward the closed position, an impedance connected in parallel with said contacts to limit the rate of rise of the circuit recovery voltage, a second pair of relatively movable contacts in series with said impedance for establishing a residual current arc, a second gas blast passage means surrounding said second pair of contacts, means responsive to the establishing of a gas blast of predetermined pressure in said first passage means for directing a portion of said gas from said first passage means to said second passage means to extinguish said residual current arc, and a conduit connecting said second passage means with said valve means for causing the exhaust gas from said second passage means to assist said spring means in closing said valve means to prevent the further escape of gas from said first passage means.

LEON R. LUDWIG.

HERBERT J. WEBB.

BENJAMIN P. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,298 Wyman Apr. 6, 1943 1,717,260 Rankin June 11, 1929 1,783,279 Brunham Dec. 2, 1930 1,904,577 Uebermuth Apr. 18, 1933 1,967,989 Clerc July 24, 1934 2,049,996 Clerc Aug. 4, 1936 2,060,282 Clerc Nov. 10, 1936 2,084,877 Uhde June 22, 1937 2,125,525 Thommen Aug. 2, 1938 2,133,938 Ruppel Oct. 18, 1938 2,222,719 Prince Nov. 26, 1940 2,240,233 Thommen Apr. 29, 1941 2,279,536 Thommen Apr. 14, 1942 2,280,321 Thommen Apr. 21, 1942 2,290,004 Thommen July 14, 1942 2,306,186 Rankin Dec. 22, 1942 2,394,086 Ludwig et al. Feb. 5, 1946

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