USING SAME

CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application claims priority to U.S. Provisional Patent Application No. 63/009,557, filed April 14, 2020 and titled “SPLIT CORE CURRENT TRANSFORMER AND METHOD OF MAKING AND USING SAME,” the entire disclosure of which is hereby incorporated by reference in its entirety.

FIELD

[0002] The presently disclosed technology relates generally to current transformers. In one optional embodiment, the presently disclosed technology relates to a water, liquid, and/or weatherproof split core current transformer, which can be especially useful outdoors, underground, and/or in road vaults, for example.

BACKGROUND AND DESCRIPTION OF RELATED ART [0003] A transformer is a passive electrical device that can transfer electrical energy from one electrical circuit to one or more circuits. A current transformer (CT) is a type of transformer used to reduce or multiply an alternating current. CTs have long been used and are useful in a variety of environments and for numerous applications, such as in underground electrical and/or utility environments like that shown in Fig. 1.

[0004] CTs, along with voltage or potential transformers, are instrument transformers. Instrument transformers scale the large values of voltage or current to small, standardized values that are easy to handle for measuring instruments and protective relays. Instrument transformers isolate measurement or protection circuits from the high voltage or current of the primary system. A CT provides a secondary current that is accurately proportional to the current flowing in its primary. A CT presents a negligible load to the primary circuit. CTs are the current- sensing units of the power system and are used at generating stations, electrical substations, and in industrial and commercial electric power applications, for example.

[0005] There are generally two types of CTs: solid core (or continuous core), such as shown in Fig. 2, and split core, such as shown in Figs. 3-6. A CT with a split core allows for the easy installation of the CT over or around the existing bus or cable conductors, thus eliminating the need to disconnect, move, and reconnect the bus or cable. In other words, split core CTs are designed for easy installation over or around large bus or wire conductors in order to make electrical load survey or for continuous monitoring of current. BRIEF SUMMARY

[0006] There is a need in the art to improve existing “weatherproof’ split core CTs. Although certain CT manufacturers offer “weatherproof’ split core CTs, such as ITI/GE Model 606 & 608, their rate of failure is high. This failure rate is the result of design and material deficiencies. For example, the over-center cam latches 10a, 10b (see Figs. 3-6), which apply force to keep the two core halves 2a, 2b together and provide environmental integrity, tend to fail by splitting apart. Further, a single O-ring 12a, 12b (see Figs. 5 and 6) encircles each of the two core splits, but is the only barrier to maintain electrical and mechanical integrity. In fact, the O-ring 12a, 12b configuration of the prior art has a tendency to push apart or impede the critical two core surfaces from mating accurately or creating a water-tight connection. The presently disclosed technology addresses the above and other deficiencies of the prior art.

[0007] Optionally, the presently technology is directed to a split core CT including at least one rotatable collar configured to removably attach an upper cap of the CT to a lower cap of the CT. Two or more O-rings can optionally be located within the collar. The collar can optionally attach to one or each of the caps by threads, which allows a user to hand- tighten the caps to insure proper mating of split core surfaces without the use of any tools. The collar can provide a mechanical barrier between the environment and all critical split CT areas, including all O-rings.

[0008] Optionally, the presently disclosed technology is directed to a split core CT including an upper cap, and a lower cap removably attachable to the upper cap. The split core CT further includes a first collar surrounding at least a portion of the lower cap in both an open and closed position. The first collar is configured to be rotatable with respect to the upper cap and the lower cap. The first collar surrounds at least a portion of the lower cap in the open position. The split core CT further includes a second collar that surrounds at least a portion of the lower cap in both an open and closed position. The second collar is configured to be rotatable with respect to the upper cap and the lower cap. The second collar surrounds at least a portion of the lower cap in the open position.

[0009] Optionally, a method according to the presently disclosed technology includes rotating a first collar from a closed position in which the first collar engages an upper cap and a lower cap of the CT to an open position in which the first collar is separated from the upper cap. [0010] Optionally, the presently disclosed technology is directed to a split core CT that provides waterproof, moisture resistant, mechanical barrier to liquid and/or various chemicals found in, above, and below ground installations.

BRIEF DESCRIPTION OF THE DRAWINGS [0011] The foregoing summary, as well as the following detailed description of the presently disclosed technology, will be better understood when read in conjunction with the appended drawings, wherein like numerals designate like elements throughout. For purposes of illustrating the presently disclosed technology, there are shown in the drawings various illustrative embodiments. It should be understood, however, that the presently disclosed technology is not limited to the precise arrangements and instrumentalities shown. In the drawings:

[0012] Fig. 1 is a perspective, partially cut-away view of an exemplary environment in which a CT is often used;

[0013] Fig. 2 is a perspective view of a solid core CT as known in the art;

[0014] Fig. 3 is a perspective view of an assembled split core CT as known in the art;

[0015] Fig. 4 is a perspective view of the prior art split core CT shown in Fig. 3, wherein one of the latches is shown in an open or disengaged position;

[0016] Fig. 5 is a perspective view of the prior art split core CT shown in Fig. 3, wherein two of the latches are shown in an open or disengaged position and a top portion of the CT is shown separated from a bottom portion of the CT for clarity;

[0017] Fig. 6 is a perspective view of a portion of the prior art split core CT shown in Fig. 5, wherein an O-ring is shown as separated from the bottom portion of the CT;

[0018] Fig. 7 is a perspective view of a split core CT according to one embodiment of the presently disclosed technology, wherein the CT is shown in a closed position with each collar shown in a first, down, or locked position;

[0019] Fig. 8 is another perspective view of the split core CT shown in Fig. 7 ;

[0020] Fig. 9 is yet another perspective view of the split core CT shown in Fig. 7, wherein the CT is shown in at least a second or partially open position;

[0021] Fig. 10 is a front elevation view of the split core CT of one exemplary embodiment of the presently disclosed technology;

[0022] Fig. 11 is a side elevation view of the split core CT shown in Fig 10; and

[0023] Fig. 12 is a magnified perspective view of a portion of the split core CT shown in

Fig. 10, wherein certain portions of the CT are shown in phantom for clarity of other components. DETAILED DESCRIPTION

[0024] While systems, devices and methods are described herein by way of examples and embodiments, those skilled in the art recognize that the presently disclosed technology is not limited to the embodiments or drawings described. Rather, the presently disclosed technology covers all modifications, equivalents and alternatives falling within the spirit and scope of the appended claims. Features of any one embodiment disclosed herein can be omitted or incorporated into another embodiment.

[0025] Any headings used herein are for organizational purposes only and are not meant to limit the scope of the description or the claims. As used herein, the word “can” is used in a permissive sense (i.e., meaning having the potential to) rather than the mandatory sense (i.e., meaning must). Unless specifically set forth herein, the terms “a,” “an” and “the” are not limited to one element but instead should be read as meaning “at least one.” The terminology includes the words noted above, derivatives thereof and words of similar import.

[0026] Referring now in detail to the drawings, wherein like reference numerals refer to like parts throughout, Figs. 7-12 show a current transformer (CT), generally designated 200, according to an aspect of the disclosed concept. The CT is optionally a split core CT. The CT 200 includes a top portion or upper cap 202a and a bottom portion or lower cap 202b.

The presently disclosed technology is not limited to a particular primary current (e.g., 600 Amp), but can be utilized and/or beneficial for various ratios or Primaries.

[0027] Optionally, the top portion 202a can be in the shape or form of an inverted “U,” and the bottom portion 202b can be in the shape or form of a “U.” The bottom portion can optionally include a first segment or leg 230 spaced-apart from a second segment or leg 232. However, other sizes, shapes, and/or configurations from that described and shown herein are possible. When the top and bottom portions 202a, 202b are properly connected or attached, the CT 200 has two, spaced-apart core connection points (one of which is shown in Fig. 12 and identified as reference number 204).

[0028] The CT 200 can include at least one rotatable collar 206a configured to removably attach the top portion 202a to the bottom portion 202b. The collar 206a can be configured to rotate about an axis that runs through and/or perpendicular to the correct connection point. Thus, by rotation, the collar 206a can move vertically upward or downward. The collar 206a can extend in a complete circle and surround at least a portion of the top portion 202a and the bottom portion 202b in an upward or “locked” position and only the bottom portion 202b (i.e., not the top portion 202a) in a downward or “unlocked” position. [0029] As shown in Fig. 9, the collar 206a can optionally include a series of internal threads 220a that are configured to engage and/or complementary mate with at least a series of threads 222a on the exterior surface of a leg or extension of the top portion 202a. In one embodiment, the collar 206a and the top portion 202a can include eight threads per inch. In another embodiment, the collar 206a and the top portion 202a can include sixteen threads per inch. However, other embodiments using different thread counts is possible. Optionally, the collar 206a and/or the top portion 202a can include a Higbee cut, which is the removal of the first thread to prevent crossing or mutilation of threads. In one embodiment, the bottom portion 202b can be devoid of threads.

[0030] Thus, the collar 206a is movable between a first, closed, or locked position (see, e.g., Figs. 7, 8 and 10-12) and a second, open, or unlocked position (see, e.g., left side of Fig. 9). In the first position, the collar 206a can engage and/or surround at least a portion of both the top portion 202a and the bottom portion 202b and thereby lock the top portion 202a with respect to the bottom portion 202b. In the second position, the collar 206a is spaced-apart from the top portion 202a and can surround at least a portion of the bottom portion 202b and thereby permit the top portion 202a to be moved with respect to the bottom portion 202b. [0031] Optionally, the at least one rotatable collar 206a includes two or more rotatable collars, such as a first rotatable collar 206a and a second rotatable collar 206b. Use of two rotatable collars can be beneficial in properly aligning the split core surfaces. The first and second collars 206a, 206b are optionally independently openable and closable with respect to each other. As a result, when the first collar 206a is in the open position and the second collar 206b is at least partially loosened from the closed position (i.e., between the fully closed and fully open position), the top portion 202a can be rotated or pivoted with respect to the bottom portion 202b (see, e.g., Fig. 9, wherein the second collar 206b is moved or positioned at least slightly upward from the fully closed position shown in Figs. 7 and 8).

The first and second collars 206a, 206b can surround separate and spaced-apart portions of the upper and lower caps 202a, 202b.

[0032] The first rotatable collar 206a can be a different color than the second rotatable collar 206b. For instance, the first rotatable collar 206a can be black, and the second rotatable collar 206b can be white. The different colors can help the user properly and quickly reassemble the CT. In one embodiment, the different colors prevent the user inadvertently assembling the CT backwards.

[0033] Additionally or alternatively, each of the top portion 202a and the bottom portion 202b can include at least one polarity indicator, such as a first polarity dot 203 a and a second polarity dot 203b. Optionally, the polarity indicators can be vertically aligned when the CT 200 is properly assembled (see Figs. 7 and 8).

[0034] In contrast to the prior art, each core connection point can optionally include a plurality of O-rings or washers. For example, in one optional embodiment, each collar surrounds three O-rings or washers. A first O-ring or washer 208a is shown in Fig. 12. Optionally, each first O-ring 208a can be an Oil-Resistant Buna-N Back-up Ring, Dash #231, ID 2.631, OD 2.867 (listed as width 0.118), Thick 0.05 -McMaster-Carr P/N 5288T274. A first gland 210a sized and shaped to receive at least a portion or the entirety of a second O- ring or washer 208a is identified in Fig. 12, and a second gland 210b sized and shaped to receive at least a portion or the entirety of a third O-ring or washer 208b is also identified in Fig. 12. Optionally, the second and third O-rings 208a, 208b can each be Oil-Resistant Buna- N, Dash #149, ID 2.8, OD 3.006, Width/Thick 0.103 -McMaster-Carr P/N 9452K156. A transformer core 212 and secondary windings 214 are also shown in Fig. 12.

[0035] Optionally, one or more components of the CT 200, such as the upper cap 202a, the lower cap 202b, the first collar 206a, and/or the second collar 206b, can be formed of one or more composites, co-polymers, and/or homopolymers, such as in the form of a three-part machined and threaded composite. Optionally, a polyurethane (e.g., a filled two-part epoxy) can be used to form one or more components of the CT200. For example, a two-part polyurethane material can be poured into two molds to form the upper and lower caps 202a, 202b and to encapsulate the core and windings. Optionally, TECAFORM® AH, manufactured by Ensinger Industries, Inc., could be used to form one or more of the components of the CT 200, which is advantageous in forming the CT 200 of two different colors. Optionally, DELRIN® 150, manufactured by Plastics International, can be used. In one embodiment, fiberglass or a non-metallic material can be used to form one or more of the components of the CT 200.

[0036] The design of the presently disclosed technology offers ease of installation by allowing the two split CT halves to rotate apart, eliminating the need to take the two halves completely apart. This saves time, reduces the possibility of core reversal, and can be done by hand without the use of any tools.

[0037] The presently disclosed technology also includes methods for making and/or using a split core CT. For example, an optional method can include rotating or unscrewing the first collar 206a from a closed position in which the first collar 206a engages the upper cap 202a and the lower cap 202b to an open position in which the first collar 206a is separated from the upper cap 202a. Optionally, the upper cap 202a can be pivoted with respect to the lower cap 202b after the first collar 206a has been rotated from the closed position to the open position, and after the second collar 206b has been at least slightly loosened or moved from the fully closed position, to open the CT 200 and provide access to an interior thereof. After the CT is placed over and/or around a bus or wire, the upper cap 202a can be pivoted with respect to the lower cap 202b to close the CT 200, and the first collar 206a can be rotated or screwed from the open position to the closed position (and the second collar 206b can be tightened to the closed position) to lock the upper cap 202a with respect to the lower cap 202b.

[0038] Thus, a user does not necessarily need to fully open both the first collar 206a and the second collar 206b to install the CT 200 over and/or around the existing bus or cable conductors. In fact, when the first collar 206a is in the open position and the second collar 206b is moved at least slightly away or loosened from the closed position (but not all the way to the fully opened position where the second collar 206b is removed from the lower cap 202b), the upper cap 202a can be swung or rotated (e.g., approaching or beyond 360 degrees) with respect to the lower cap 202b.

[0039] The following exemplary embodiments further describe optional aspects of the presently disclosed technology and are part of this Detailed Description. These exemplary embodiments are set forth in a format substantially akin to claims (each set including a numerical designation followed by a letter (e.g., “A,” “B,” etc.), although they are not technically claims of the present application. The following exemplary embodiments refer to each other in dependent relationships as “embodiments” instead of “claims.”

[0040] 1A. A split core current transformer (CT) comprises a rotatable cup surrounding three O-rings to create a water-tight barrier in a closed position.

[0041] 2A. The split core CT of embodiment 1A, wherein the cup is configured to engage threads of an upper cap of the CT in the closed position.

[0042] IB. A water-proof split core current transformer (CT) includes a cup rotatably attachable to an upper cap and a lower cap of the CT, the cup surrounding three O-rings positioned between the upper cap and the lower cap in a closed position of the cup.

[0043] 2B. The water-proof split core CT of embodiment IB, wherein the cup includes a first cup and a second cup rotatably attachable to another portion of the upper cap and the lower cap of the CT.

[0044] 1C. A method of using a split core current transformer (CT), the method comprising: disconnecting at least a portion of an upper cap of the CT from a lower cap of the CT ; rotating the upper cap with respect to the lower cap about a pivot point where the upper cap is connected to the lower cap to open the CT ; installing the CT over or around a device, the device optionally being a bus or a cable; and rotating the upper cap with respect to the lower cap about the pivot point to close the CT over or around the bus or cable.

[0045] ID. A split core current transformer (CT) comprising: two or more O -rings between a top potion of the CT and a bottom portion of the CT; and at least one threaded collar configured to removably attach the top portion to the bottom portion.

[0046] 2D. The split core CT of embodiment ID, wherein the top portion and the bottom portion are formed of at least one co-polymer or homopolymer.

[0047] 3D. The split core CT of embodiment ID, wherein the collar includes sixteen threads per inch.

[0048] 4D. The split core CT of embodiment ID, wherein the collar includes eight threads per inch.

[0049] While the presently disclosed technology has been described in detail and with reference to specific examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. It is understood, therefore, that the presently disclosed technology is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present presently disclosed technology as defined by the appended claims.