US3328648A

US3328648A - Combination plug-in block with current transformers

Info

Publication number: US3328648A
Application number: US546361A
Authority: US
Inventors: Carl E Gryetko
Original assignee: ITE Circuit Breaker Co
Current assignee: Siemens Energy and Automation Inc; ITE Circuit Breaker Co
Priority date: 1966-04-29
Filing date: 1966-04-29
Publication date: 1967-06-27
Anticipated expiration: 1984-06-27

Description

2 Sheets-Shem 1 C. E. GRYCTKO ICE-.1-

COMBINATION PLUG- IN BLOCK WITH CURRENT TRANSFORMERS June 27, 1967 Filed April 29, 1966 June 27, 1967 c. E. GRYCTKO COMBINATION PLUG-IN BLOCK WITH CURRENT TRANSFORMERS Filed April 29, 1966 2 Sheets-Sheet 2 INVENTOR. 534/5; 5. eyarA a WUH United States Patent O 3,328,648 COMBINATION PLUG-IN BLGQK WITH CURRENT TRANSFORMERS Carl E. Gryctko, Haddon Heights, N.J., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Apr. 29, 1966, Ser. No. 546,361 2 Claims. (Cl. 317-119) This invention relates to circuit breaker installations and more particularly to the manner in which an insulating mounting block may insulatingly support one or more current transformers with respect to conductors passing through such current transformers and such mounting block in such a manner as to aid in the support of such conductors while at the same time minimize the thickness of the overall mounting block and current transformer combination.

Generally speaking, the instant invention is applicable to at least two types of circuit breaker installations, one of which may be conveniently classified as large drawout circuit breaker installations, the other classified as smaller, molded case circuit breaker installations.

Drawout type circuit breaker installations generally require a circuit breaker cubicle through the rear wall of which passes the conductors of the line being protected by the circuit breaker installation. Customarily, a circuit breaker is movable within such cubicle and includes at least one pair of disconnect contacts which are engageable with the conductors passing through the rear wall of the cubicle when the circuit breaker is moved to the rear of the cubicle by suitable racking mechanism. For inspection and repair, the door of the cubicle may be opened so that the circuit breaker may be completely withdrawn from its cubicle.

Furthermore, prior art drawout circuit breaker installations normally include some kind of insulating mounting block which forms a portion of the rear wall of the cubicle in which the circuit breaker is housed. The insulating mounting block is provided with apertures and suitable fastening means for maintaining the conductors which pass therethrough in fixed insulating relationship with the remainder of the circuit breaker cubicle and in aligned relationship with the disconnect contacts of the circuit breaker so as to facilitate the connection therebetween. Thus to protect the incoming line, the circuit breaker is racked toward the rear of the cubicle such that the disconnect contacts thereof automatically engage the tips of the conductors passing through the insulating mounting block.

In most drawout circuit breaker installations it has been found desirable to utilize current transformers in combination with the incoming line being protected, the flux linkage between the two assuring that the current tapped off at any time is directly proportional to the current being carried by the main cables. There are many possible uses for the current tapped by such transformers, one important one of which would be monitoring the quantity of current flowing through the circuit being protected.

Generally such current transformers take the form of a cylindrically or conically shaped body having a central aperture passing therethrough such that the main conductor of the line being monitored may pass through the aperture to provide the primary of the transformer, The cylindrically or conically shaped body further includes secondary leads from which the secondary current may be drawn. In the prior art such transformers are generally secured to either one side or the other of the insulating mounting block which forms a portion of the rear wall of the circuit breaker cubicle. From the point of view of safety it has made no difference whether 3,328,648 Patented June 27, 1967 such current transformers were located on one side or the other of the insulating mounting block; since when the circuit breaker is disconnected from the incoming cables, no current is flowing through the primary of the transformer (i.e., the line being protected) and consequently there is no danger of harm to any one coming into contact with the secondary leads of such transformers.

However, the securement of such current transformers to either side of the insulating mounting block resulted in several disadvantages which the instant invention effectively overcomes. For example, it is apparent that in order to secure such current transformers to either side of the insulating mounting block, some type of securing means must be provided in order to firmly secure the transformers to the block. Secondly, it becomes apparent that when such current transformers are added to either side of the insulating mounting block described, the overall thickness of the mounting block is increased by the thickness of the current transformer which is secured thereto and projects therefrom. The disadvantages discussed above result in additional cost in providing material and labor for securing current transformers to the insulating mounting blocks, and furthermore result in an uneconomical utilization of space caused by the increased thickness of the mounting block and projecting current transformers.

In smaller molded case circuit breaker installations it has been similarly found desirable to utilize current transformers in combination with the incoming line being pro tected, with the flux linkage between the two being proportional to the current being carried by the line. However, securement of such current transformer to one side of an insulating block which the molded case circuit breaker eventually rests has resulted in disadvantages similar to those encountered with large drawout type circuit breakers. Specifically, in order to secure such current transformers to the cooperating insulating mounting block, some type of securing means must be provided, thus requiring higher costs and additional labor in the field. Furthermore, when such current transformers are added to the insulating mounting block the overall thicknes of the mounting block is increased by the thickness of the current transformer which is secured thereto and projects therefrom.

In contradistinction to the prior art technique of mechanically securing current transformers to an insulating mounting block, the instant invention, as applicable to either drawout type or molded case circuit breaker installations, provides a structure whereby the current transformers are integrally supported within the cooperating insulating mounting block in such a manner as to completely eliminate the need for additional securing means to secure such transformers to the mounting block, while at the same time materially reducing the overall thickness of the combination of mounting block and current transformer.

In accordance with the instant invention the current transformers are encapsulated within the insulating mounting block in such a manner that the central apertures of the current transformers are coaXially aligned with the apertures through the mounting block whereby the conductors which pass therethrough may be securely maintained relative to the current transformers, relative to the insulating mounting block, relative to one another, and relative to the cooperating circuit breaker without the need of additional securing means. Thus the instant invention reduces the cost of parts and installation, while at the same time providing for the most economical use of the space immediately surrounding the insulating mounting block.

As an advantageous feature of the instant invention, the principles suggested thereby may be applied to differ- 3 erent types of circuit breakers, and more particularly may be applied to both the drawout type and moldedcase circuit breaker installations discussed above.

Accordingly, it is an object of the instant invention to provide the combination of an insulating mounting block and a current transformer supported within said mounting block for supporting such transformer relative to a conductor which passes through the mounting block and transformer in such a manner as to eliminate the need for additional securing means for securing the transformer to the insulating block, while at the same time minimizing the overall thickness of the combination of mounting block and current transformer.

It is another object of the instant invention to provide such a combination of mounting block and current transformer supported therewithin which further serves the function of supportingly aligning conductors which pass therethrough relative to the disconnect contacts provided on the rear of a circuit breaker which cooperates with the conductors passing through such mounting block.

It is another object of the instant invention to provide an insulating mounting block in combination with a current transformer which is encapsulated therein so as to facilitate an integral construction without the need for additional securing means and in a manner which most efliciently utilizes space immediately surrounding such mounting block.

Still another object of the instant invention is to provide such a combination of insulating mounting block and current transformers which may be applied to different types of circuit breaker installations.

Other objects and a fuller understanding of the instant invention may be had by referring to the following description taken in conjunction with the following drawings, in which:

FIGURE 1 is a somewhat schematic side view of a circuit breaker installation embodying the instant invention;

FIGURE 2 isa view taken along the arrows 2-2 of FIGURE 1; and

FIGURE 3 is an exploded perspective view of an alternative embodiment of the instant invention.

Referring to FIGURE 1, there is shown a drawout type circuit breaker installation which includes a circuit breaker cubicle 12 within which is movable a circuit breaker 14 between a first position indicated in solid line in FIGURE 1, and a second position 14' indicated by the phantom line in FIGURE 1. Cubicle 12 includes a hinged door 16 which may be opened to facilitate the removal of circuit breaker 14 from cubicle 12.

The rear wall 18 of circuit breaker cubicle 12 includes as an integral portion thereof an insulating mounting block 20 through which the

incoming conductors

22 and 24 may pass through

apertures

26 and 28, respectively. Incoming

conductors

22 and 24 represent the line which is to be protected from instantaneous fault and/ or delayed overload conditions by circuit breaker 14.

Circuit breaker 14 includes a pair of

rear conductors

30 and 32 upon which are mounted the

disconnect contacts

34 and 36, respectively. With the circuit breaker 14 in the position indicated by the solid line drawing,

disconnect contacts

34 and 36 are isolated from

conductors

22 and 24 such that no current may flow therethrough. When circuit breaker 14 is racked to the position indicated at 14', the

disconnect contacts

34 and 36 are automatically telescoped onto

conductors

22 and 24 such that the line represented by such conductor-s will be protected from fault condition by circuit breaker 14. As the details of circuit breaker 14 form no part of the instant invention, and since a variety of circuit breakers well known in the art may fulfill the function of circuit breaker 14, further discussion of the operation thereof is thought unnecessary in this specification. Furthermore, it is to be noted that although the instant invention is and will be described with respect to a three-phase system, it should be understood that the instant invention is in no way dependent upon a number of phases utilized and may function equally as well with a lesser or greater number.

As noted previously, in many circuit breaker installations it is desirable to utilize current transformers to tap off of the lines being protected. Such current transformers generally take the form of cylindrically or conically shaped bodies having a central aperture passing therethrough such that when the conductor of the line being protected is inserted therein such conductor acts as the primary coil of the transformer configuration. Also, as noted previously, prior art techniques for supporting such current transformers relative to an insulating mounting block such as 20 in FIGURE 1, normally consist of mounting such current transformers on either

side

38 or 40 of insulating block 20 such that the current transformers would extend for their entire thickness from either of such sides. Obviously such technique would require additional securing means for supporting the current transformers on side 38 or 40'; would necessarily require the services of skilled laborers to perform such securing operation; and furthermore would increase the overall thickness of the insulating mounting block 20 by the thickness of the current transformers mounted thereon and projecting therefrom,

In accordance with the teachings of the instant invention current transfor'mers 42 through 52 (see FIGURE 2),

transformers

42 and 44 which may be seen in the side view of FIGURE 1, are supported within the insulating mounting block 20 such that the major portions thereof lie within the sides defined by 38 and 40 in FIG- URE 1. Preferably, transformers 42 and 44 (and 4652) are encapsulated within insulating mounting block 20 during the molding thereof such that

apertures

54 and 57 in the

transformers

42 and 44 are coaxially aligned with

apertures

26 and 28 in insulating mounting block 20. It will become apparent that the encapsulation of current transformers 4252 within the insulating block 20 completely eleminatcs the need for any additional securing means for securing such transformers relative to the insulating block, thereby also eliminating the corresponding need for labor, while at the same time substantially minimizing the overall thickness of the combination of insulating block 20 and transformers 4252. It should be further apparent that the self-contained integral combination of the current transformers within the insulating block 20 materially aids in supporting the

conductors

22 and 24 relative to the insulating block 20' and in maintaining such conductors in proper alignment with respect to the

disconnect contacts

34 and 36 of circuit breaker 14.

Referring to FIGURE 2, there is shown a front view of the insulating mounting block 20 taken along the arrows 22 of FIGURE 1 in which the current transformers 42-52 may be seen in phantom as surrounding the

conductors

22, 24, 22, 24', and 22", 24", respectively. Each of current transformers includes secondary conductors 56 and 58 which terminate in

secondary terminals

60 and 62, respectively, from which the secondary current may be drawn.

With the circuit breaker 14 moved to its connected position 14',

disconnect contacts

34 and 36 are automatically telescoped onto

conductors

22, 24 of the line being protected. Assuming the breaker to be closed, i.e., with the incoming line defined by

conductors

22 and 24 carrying acceptable current values,

such conductors

22 and 24 function as the primary for the

current transformers

42 and 44 such that

secondary terminals

60 and 62 may be monitored to determine the current flow through

conductors

22 and 24.

Turning now to FIGURE 3, there is shown an alternative embodiment of the instant invention in which a molded case circuit breaker will be eventually seated on and secured to an insulative mounting block 72 such that the line and load side contacts (not shown in FIG- URE 3) provided on the undersurface 74 of circuit breaker 70 will be mechanically and electrically con nected to upstanding conductive studs such as 76, 78 on the line side and 80, 82 on the load side which pass through apertures such as 84, 86, and 88, 90 provided within the central planar portion 92 of insulative mounting block 72 when conductive bars such as 94 and 96 are secured by suitable fastening means to the underside 98 of insulative block 72.

As in the case of large drawout type circuit breaker installations it is desirable that current transformers be provided on the line side of the circuit being protected such that the current values flowing therethrough may be continuously monitored. To this end, and in accordance with the teachings of the instant invention, current transformers 100, 102 and 104 (one for each phase of a three-phase system) are encapsulated within the insulative mounting block 72 such that their respective apertures 101, 103 and 105 encompass the respective pairs of apertures 84, 86. It is noted that such current transformers are completely enclosed within the surfaces 92 and 98 and do not project from either side thereof thus minimizing the thickness of the overall combination.

It will be appreciated that when the conductive bar 94 is secured to the undersurface 98 of mounting block 72, the upstanding conductive studs 76, 78 will pass through apertures such as 84, 86 and as such will function as the primary for the transformers 100, 102 and 104 when the circuit breaker contacts (not shown) are connected to their cooperating conductive studs.

Current transformers 100, 102 and 104 are provided with

secondary leads

106 and 108 similarly encapsulated Within the mounting block 72 with connecting portions thereof passing into notched

recesses

110, 112 and 114 wherein they may be electrically connected to suitable terminals such as 116 and 118.

Preferably, the current transformers 100, 102 and 104 and their associated

secondary leads

106 and 108 are encapsulated within the insulative block 72 during the molding thereof thereby simplifying the production of the overall assembly. Although a three-phase system has been illustrated in FIGURE 3, it is to be understood that a lesser or greater number of phases may be utilized and furthermore, if desired, current transformers such as 100, 102 and 104 could be similarly provided to surround either more or less apertures such as 84, 86 and similarly could be located around apertures such as 88 and 90 if it were desirable to monitor current flowing in the load side of the circuit.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.

What is claimed is:

1. In combination:

a circuit breaker mounting block of insulating material,

said mounting block having an aperture therethrough;

a first electrically conductive member extending through said aperture;

a circuit breaker supported on said mounting block,

said circuit breaker having a terminal contact connected to said electrically conductive member to permit the flow of current therebetween; and

a current transformer encapsulated Within said circuit breaker mounting block, said transformer including an aperture therethrough which encompasses the aperture of said mounting block such that said electrically conductive member passes through the aperture in said transformer in addition to passing through the aperture in said mounting block;

whereby any flow of current between said electrically conductive member and said circuit breaker may be detected by said current transformer.

2. The combination of claim 1, wherein said circuit breaker mounting block includes a second aperture through which .a second electrically conductive member passes, said first and second conductive members being electrically connected to one another; said aperture of said current transformer encompassing both said first and second apertures in said mounting block.

References Cited UNITED STATES PATENTS 2,925,570 2/1960 Strock 336-96 3,024,434 3/ 1962 Carson 336-96 3,229,058 1'/l966 Schymik ZOO-50.15

ROBERT K. SCHAEFER, Primary Examiner. M. GINSBURG, Assistant Examiner.

Claims

1. IN COMBINATION: A CIRCUIT BREAKER MOUNTING BLOCK OF INSULATING MATERIAL, SAID MOUNTING BLOCK HAVING AN APERTURE THERETHROUGH; A FIRST ELECTRICALLY CONDUCTIVE MEMBER EXTENDING THROUGH SAID APERTURE; A CIRCUIT BREAKER SUPPORTED ON SAID MOUNTING BLOCK, SAID CIRCUIT BREAKER HAVING A TERMINAL CONTACT CONNECTED TO SAID ELECTRICALLY CONDUCTIVE MEMBER TO PERMIT THE FLOW OF CURRENT THEREBETWEEN; AND A CIRCUIT TRANSFORMER ENCAPSULATED WITHIN SAID CIRCUIT BREAKER MOUNTING BLOCK, SAID TRANSFORMER INCLUDING AN APERTURE THERETHROUGH WHICH ENCOMPASSES THE APERTURE OF SAID MOUNTING BLOCK SUCH THAT SAID ELECTRICALLY CONDUCTIVE MEMBER PASSES THROUGH THE APERTURE IN SAID TRANSFORMER IN ADDITION TO PASSING THROUGH THE APERTURE IN SAID MOUNTING BLOCK; WHEREBY ANY FLOW OF CURRENT BETWEEN SAID ELECTRICALLY CONDUCTIVE MEMBER AND SAID CIRCUIT BREAKER MAY BE DETECTED BY SAID CURRENT TRANSFORMER.