US3043933A

US3043933A - Polyphase circuit interrupters

Info

Publication number: US3043933A
Application number: US857661A
Authority: US
Inventors: William J Weinfurt
Original assignee: McGraw Edison Co
Current assignee: McGraw Edison Co
Priority date: 1959-12-07
Filing date: 1959-12-07
Publication date: 1962-07-10
Anticipated expiration: 1979-07-10

Description

y 1962 w. J. WEINFURT POLYPHASE CIRCUIT INTERRUPTERS Filed Dec. 7, 1959 F] Ci 3 INVENTOR.

WlLLlAM J.W|NFURT ATTO2NEY United States Patent Filed Dec. 7, 1959, Ser. N0.857,661 3 Claims. (Cl. 200-97) This invention relates to polyphase circuit interrupters. Objects of this invention are to vastly simplify the construction of polyphase circuit interrupters and a primary object of this invention is to provide hydraullic means responsive to overloads in one or more of the phases for simultaneously controlling all of the phases.

A specific object is to provide hydraulic means responsive to overloads so that the timing for opening the circuit interrupter is controlled by the largest overload in any one phase, independently of a lesser overload in any other phase, and in which the effect of only one overload, viz the largest overload, determines the timing.

A further primary object is to prevent the adding together of the efiects of several overloads in different phases, and to control the timing as though only one overload was acting, as stated hereinabove.

A further primary object is operate the latch control of a polyphase circuit interrupter as nearly as possible as a function of pressure only.

A further object is to provide means for improving the operation and simplifying the construction of polyphase circuit interlupters of the type shown in Patent Number 2,804,521, of August 27, 1957, of Van Ryan and Date, assigned to the same assignee as the present invention, in which it will not be necessary to use an interrupted trip bar, as in such patent, but in which a continuous unbroken trip bar may be used, thus greatly simplifying the mechanical construction of the polyphase circuit interrupter.

Other objects and improvements will appear as the description proceeds.

Referring to the drawing, in which a few of the many forms in which the invention could be used, it will be seen that:

FIGURE 1 is a view of one form of the invention.

FIGURE 2 is a fragmentary view of a modification of the invention.

FIGURE 3 is a view showing how the invention could be applied to polyphase circuit interrupters as previously constructed, and used to replace the complicated mechanical constructions.

Referring to FIGURE 1, it will be seen that three identical phase units are shown as I, II, and III. Each is composed of a series coil surrounding a plunger or armature 1 which is held in fixed position in the coil by its attachment to the bellows 2. The lower end of the bellows is mounted fixedly as shown. When an over-' current flows in the coil, the plunger 1 is caused to exert a force on the top of the bellows tending to collapse it. The lower end of each bellows is connected by an insula-ting tube to a manifold 3 in such a manner that the bellows, tubing connections and manifold comprise a fluid tight vessel. 0n the right hand end of the manifold is 3,043,933 Patented July 10, 1962 latching and time delay arrangement shown may be arranged in any suitable manner and the one shown'is intended only to illustrate the principle of operation. As an alternate to the Bourdon tube element, a small cylinder with a movable piston as shown at 11 could be used. At 9 is shown an expansion standpipe connected into the manifold (or any point in the closed system). The lower end of the standpipe is provided with a check valve normally biased open but pressure from the manifold close it rapidly. The whole system comprising the bellows, tubes, manifold, Bourdon tube and standpipe is completely filled with hydraulic liquid.

The theory of operation is as follows: It is the purpose of this invention to operate the latch as nearly as possible a a function of pressure only. If the series coils acting on the plunger cause the bellows to generate a pressure which is a function of the current magnitude, then this pressure will act against all elements of the closed hydraulic system. If a current of lesser magnitude flows in either or both of the other coils, their respective bellows will attempt to generate a lesser pressure which will be ineffective since a greater pressure already exists in the system. The net result of any pattern of currents in the coils will be a pressure in the system which is directly related to the highest current. It is understood that no appreciable displacement takes place in any of the plungers to generate the pressure. When the pressure attains a certain value, it will act on the Bourdon tube element of the pressure operated device which operates sub stantially solely as a pressure function to exert a force on the free leg. This force acting on the time delay unit will take a definite time to complete the unlatching operation, thus giving time to unlatch as a function of current magnitude. It is obvious that it is impossible to work a system on pressure alone since in order to do some work on the latch pressure must be translated into a force acting through some distance. Therefore, some displacement of fluid is necessary. The success of the independent operation of the phase elements on a common time delay relies on the degree to which displacement can be limited. To attain this a latch system requiring very little work to operate should be employed, the piston in 11 or the Bourdon tube volume should be small with respect to the effective area of the bellows 2. The standpipe is necessary to allow for thermal expansion in the closed system when no overcurrent exists. The check valve 8 will take the standpipe out of the system when overcurrent pressures exist in the manifold.

Any suitable automatic or manual resetting means such as 12 could be used.

In FIGURE 3, it will be noted that the free end of the Bourdon tube is connected to the trip bar 35 by a rigid connecting member W.

a closed Bourdon tube type element shown as 4 which is a pressure operated device and operates substantially solely as a pressure function. The free leg of the tube 4 is linked to latch 5 by a link in such a manner that a movement of the free end of 4 to the right will unlatch the arm on operating shaft 6, allowing 6 to rotate clock- Although the invention has been described in considerable detail, it is to be understood that such description is intended as illustrative and not limiting, as the invention is to be limited only as claimed.

I claim:

1. Means for controlling a polyphase circuit interrupter comprising a plurality of electromagnets, one for each phase, responsive to overload current, a hermetically closed hydraulic system including a hydraulic manifold, a hydraulic compressing means for each electrornagnet mechanically operated by the corresponding electromagnet and each being hydraulically connected to said manifold, a pressure operated device operating as a pressure function hydraulically connected to said manifold, a polyphase circuit interrupter having a switch for each phase, and mechanism operatively connecting all of said switches with said pressure operated device for simultaneously opening all of said switches upon operation of said pressure operated device.

2. Means for controlling a polyphase circuit interrupter comprising a plurality of electromagnets, one for each phase, responsive to overload current, a hermetically closed hydraulic system including a hydraulic manifold, a hydraulic compressing means-for each electromagnet mechanically operated by the corresponding electromagnet and each being hydraulically connected to said manifold, a pressure operated device operating as a pressure function hydraulically connected to said manifold, the volume of said pressure operated device being relatively small as compared with the volume of said hydraulic compressing means, a polyphase circuit interrupter having a switch for each phase, and mechanism operatively connecting all of said switches with said pres sure operated device for simultaneously opening all of said switches upon operation of said pressure operated device.

3. Means for controlling a polyphase circuit interrupter comprising a plurality of electromagnets, one for each phase, responsive to overload current, a hermetically closed hydraulic system including a hydraulic manifold, a hydraulic compressing means for each electromagnet mechanically operated by the corresponding electromagnet and each being hydraulically connected to said manifold, a pressure operated device operating as a pressure function hydraulically connected to said manifold, a polyphase circuit interrupter having a switch for each phase, and mechanism operatively connecting all of said switches with said pressure operated device for simultaneously opening all of said switches upon operation of said pressure operated device, and reservoir means connected to said hydraulic system and having normally open check valve means arranged to close when said hydraulic compressing means operates.

References Cited in the file of this patent UNITED STATES PATENTS 2,392,282 Byerlay Jan. 1, 1946 2,441,412 Haller May 11, 1948 2,765,378 Perry et al Oct. 2, 1956 2,920,607 Barkan Jan. 12, 1960 2,972,709 Chabala Feb. 21, 196 1