US2555993A

US2555993A - Circuit interrupter

Info

Publication number: US2555993A
Application number: US100726A
Authority: US
Inventors: John A Oppel; Charles H Titus
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1949-06-22
Filing date: 1949-06-22
Publication date: 1951-06-05
Anticipated expiration: 1968-06-05
Also published as: FR1020436A

Description

June 5, 1951 J. A. OPPEL EI'AL CIRCUIT INTERRUPTER Filed June 22, 1949 Inventors John A. Oppel, Char! es H.Titus Their Attorney.

- trol circuit interrupter.

Patented June 5, 1951 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Application June 22, 1949, Serial No. 100,726

5 Claims.

This invention relates to electric circuit interrupters and moreparticularly to interrupters used in connection with control circuits for electric apparatus such as circuit breakers, for example. 1

In large power circuit breakers whose contacts are biased to the open position by heavy spring means and which are closed through the agency of a solenoid, the current through the solenoid required to move the heavy circuit breaker parts to the closed position against the opposition of the relatively large biasing springs may be of the order of 200 amperes or more and frequently, direct rather than alternating current is used for this purpose. does not have an instantaneous value of zero amperes together with the fact that the power circuit breaker solenoid has a relatively high inductance are factors which tend to maintain the are drawn between the contacts of the con- Of course, it is desirable to interrupt this solenoid current in an eflicient manner immediately after its circuit breaker closing function is accomplished, so as to avoid possible damage to the solenoid coil such as by excessive temperature rise. Also particularly for reclosing duty, it is required that the control circuits be reestablished immediately in readiness for subsequent repeated operations.

Frequently, the space available for mounting the solenoid circuit control interrupter is limited so that provision must be made for efiiciently dissipating the energy of the are drawn upon interruption of the solenoid current and at the The fact that direct current same time, means must be provided for protecting various devices in the vicinity of the control interrupter from possible damage due to are flames and from electrical interference by the arc and highly ionized gases which would constitute a hazard to the proper operation of ad- Other objects and advantages of our invention will become apparent as the following description proceeds and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

; tion of the arc chamber.

-. nates a cooperating movable contact.

In accordance with our invention, an expansion chamber communicates through a restricted slot-like passage with a vented arcing chamber containing separable contacts. Means are provided for movin the are drawn upon separation of the contacts toward the restricted passage. Thus, the energy of the arc, which takes the form of heat is temporarily stored and to some extent dissipated by expansion in the expansion chamber and, after interruption of the arc, the gases received in the expansion chamber are allowed to pass back through the restricted slotlike passage to atmosphere by way of the vented arcing chamber. The physical presence of the arc in the restricted passage effectively impedes the discharge of these gases from the expansion chamber until after the arc is interrupted. Thus, during the whole process of drawing and extinguishing the arc, there is little possibility for damaging flames to escape from the confines of the expansion chamber through the restricted passage since the arc is constrained to move in a direction toward the expansion chamber which is in a direction divergent from the vented por- Thus, interruption of the arc is facilitated because the expansion chamber effectively disperses and cools the ionized particles produced in the region of the are.

In the drawings, Fig. 1 represents a side view partially in section of an interrupter embodying our invention; Fig. 2 is an end view showing only the arc chute element as it would appear looking from the right hand side of Fig. 1, i. e., with the contact structure omitted; Fig. 3 is a side view showing the arc chute alone as it would appear from the left hand side of Fig. 1; 4 is a bottom view of the arc chute structure shown in Fig. 1 omitting the contact structure; Fig. 5 is a sectional view taken along the line 5-5 of Fig. 1; Fig. 6 is a sectional view along the line of 6-6 of Fig. 1; and Fig. '7 is a sectional view taken along the line 1-1 of Fig. 1.

With reference to Fig. l, the numeral l designates a fixed contact while the numeral 2 desig- Secured to the contact I by means of the screw 3 is an arc runner 4. One terminal of the blow-out coil 5 is connected to the arc runner 4 at 6 in any suitable manner and the other terminal of the blowout coil 5 is connected to a suitable terminal of the control circuit interrupter by the screw 8. The movable contact 2 also is provided with an arc runner or arcing tip 1. Metallic pole plates 9 are mounted one in back and one in front of the blow-out coil 5, these plates constitutin the two pole pieces which are ma netically interconnected with a core piece disposed within the coil 5. Only the rear one of these magnetic plates is shown in Fig. l. The magnetic plates 9 with their core and the coil 5 produce a field which is effective to move by motor action the are drawn between contacts I and 2 along arc runners 4 and 1 and in a direction generally upward and somewhat to the right as is well known.

Contact 2 is connected by flexible lead [0 to the control circuit through a convenient terminal (not shown) and is movable in unison with its insulating support block ll into and out of engagement with contact I by any suitable known mechanism. The contacts I and 2 are disposed within the relatively narrow arcing chamber 12 formed between the recessed front and back walls l3 of the unitary arc chute assembly as best seen in Fig. 6; this chamber being flanked by the pole plates 9 which are disposed into the recessed walls 13. The unitary arc chute assembly l3 preferably is constructed of phospho-asbestos with a 90% zircon filler. Although the arcing chamber i2 is open at the bottom, the arc does not move toward this opening because of the action of the strong magnetic field together with thermal effects. Accordingly, the arcing chamber i2 properly vents to, atmosphere only through the exhaust passage I 6 which, as shown, discharges in a direction which is divergent from that of the general direction of the ma netic blow-out action.

The hoodlike expansion chamber H is relatively large when compared with the volume of the narrow space designated as the arcing chamber. Communication between the arcing chamber 12 and the expansion chamber H is afforded only by means of the restricted slot-like passage l8. The passage i8 at its lower end flares toward the arcing chamber as indicated in Fig. 6 by the numeral I9 and in Fig. l by the spaced horizontal lines. A baffie structure comprising the lip 26 permits but an indirect restricted path for limiting the emission of hot products of arcing from within the expansion chamber through the exhaust passage 56 to atmosphere, as well as providing means for preventing undue bowing of the are into the vent it.

The are chute is held in position by means of a fixed pin (not shown) mounted on suitable supporting structure and extending through the opening 25. Although, the arc chute has been described. as being one integral unit, it is convenient to manufacture it as a pair of mating molded halves, cemented together to form virtually the unitary structure as shown in the drawings.

When contact 2 is moved out of engagement with contact I, the arc drawn bowed and quickly moved upward and somewhat to the right by the magnetic blow-out action in, the general direction of the plates 8. Because of this strong magnetic action and the lateral divergency of the passage it, the arc does not escape through the exhaust vent it. When the arc encounters the surfaces l9. it is constricted along its length and thereby cooled during its movement upwardly through the restricted slot-like passage R8. The energy of the are which takes the form of heat is effective to raise the temperature of the restricted passage [8 and the air within the arc chute in the region of the arc. The resulting hot gases, being highly ionized, would tend to prolong the are if allowed to remain in close proximity thereto and, in known devices, such gases usually are merely liberated to atmosphere through some suitable channeling means. When this ionized gas is expelled more or less directly from the arc chute in known devices, resultant hot flames frequently are emitted to the outside of the chute.

In accordance with our invention, these hot flames are entrapped Within the expansion chamber I! so that damage to adjacent apparatus from direct emission from the chute is prevented. The chamber I! also aids in interrupting the are by removing the ionized particles from the immediate vicinity of the arc and by affording expansion space for the hot gases. This expansiOn of the gases tends to cool the gases, and together with heat extracted by the chute struc ture aids interruption by cooling action. Once the arc is extinguished, the gases entrapped within chamber ll quickly escape back through the restricted slot-like passage l8 into the arc chamber 52 and there disperse through the exhaust vent IE to atmosphere.

The baffie or lip 20, as already pointed out, aids in preventing any undue bowing of the are into the exhaust vent i6. As is described in Patent 2,460,727-Atwood et al., assigned to the assignee of this invention, the moving contact are root is prevented from dwelling at a particular spot on the arc runner T partly because the arc runner 7 is curved at an angle of or more as shown, in Fig. 1.

-While We have shown and described a particular embodiment of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from our invention and we, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters. Patent of the United States is:

1. An electric circuit interrupter comprising an arcing chamber constructed of insulating material, separable contacts in said arcing cham-- ing chamber arranged to cause the gases returned to said arcing chamber to be directed to atmos-' phere in, a direction generally transverse to the direction of movement of the arc in said restriated passage.

2. An electric circuit interrupter comprising an arcing chamber constructed of insulating material, separable contacts in said arcing chamber, a hoodlike expansion chamber, a restricted passage afiording communication between said arcing and said expansion chambers, means for moving the are drawn upon separation of said contacts into said restricted passage and in a direction toward said expansion chamber, said expansion chamber being effective to receive from said restricted passage and to retain mo' mentarily the hot gases produced by the arc and to return the gases to said arcing chamber through said restricted passage after interruption of the arc, and an exhaust vent leading from said arcing chamber to atmosphere for directing the gases from said arcing chamber in a direction generally transverse with respect to the direction of movement of the are from said arcing chamber toward said expansion chamber.

3, An electric circuit interrupter comprising an arcing chamber constructed of insulating material, separable contacts in said arcing chamber, ahoodlike expansion chamber of substantiallyv greater volume than said arcing chamber, a restricted slot-like passage affording communication between said arcing and said expansion chambers, means for moving the are drawn upon separation of said contacts into said restricted passage and in a direction toward said expansion chamber, said expansion chamber being efiective to receive from said restricted passage and to retain momentarily the hot gases produced by the arc and to return the substantially cooled gases to said arcing chamber through said restricted passage after interruption of the arc, and an, exhaust vent leading from said arcing chamber to atmosphere for directing the gases from said arcing chamber in a direction transverse to the direction in which said are is moved by said means for moving the arc, said exhaust vent being positioned to receive therein the arcing tip 'of a movable one of said contacts when such contact is in the open position.

4.'An electric circuit interrupter comprising an arcing chamber constructed of insulating material, separable contacts in said arcing chamber, an exhaust vent leading from said arcing chamber disposed to receive therein an arcing portion of a movable one of said contacts when such contact is in the open position, a hoodlike expansion chamber of substantially greater volume than said arcing chamber, a restricted passage affording communication between said areing and said expansion chambers, and means for moving the are drawn upon separation of said contacts into said restricted passage in a direction substantially transverse to the direction of movement of said movable one of said contacts, said expansion chamber being efiective to receive a substantial portion of the hot gases produced by the arc and forced through said restricted passage by the arc and to regurgitate such gases through said restricted passage after interruption of the arc.

5. An electric circuit interrupter comprising an arcing chamber constructed of insulating material, separable contacts in said arcing chamber, an exhaust vent leading from said arcing chamber disposed to receive therein an arcing portion of a movable one of said contacts when such contact is in the open position, a hoodlike expansion chamber of substantially greater volume than said arcing chamber, a slot-like restricted passage affording communication between said arcing and said expansion chambers the length of said passage lying in the same plane as the path of the are, means for moving the are drawn upon separation of said contacts into said restricted passage in a direction substantially transverse to the direction of movement of a movable one of said contacts, said expansion chamber being eifective to receive a substantial portion of the hot gases produced by the arc and forced through said restricted passage by the arc and to discharge such gases through said restricted passage after interruption of the arc, and baffle means interposed between said expansion chamber and said exhaust vent and disposed at one end of said restricted passage for preventing the emission of arc flames from said expansion chamber through said restricted passage and into said exhaust passage.

JOHN A. OPPEL. CHARLES H. TITUS.

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

UNITED STATES PATENTS 2,492,726 Ayers et al Dec, 27, 1949