Prosecution Insights
Last updated: April 19, 2026
Application No. 18/020,708

A TAP CHANGER AND A TRANSFORMER ARRANGEMENT COMPRISING THE TAP CHANGER

Non-Final OA §103
Filed
Feb 10, 2023
Examiner
BARNES, MALCOLM
Art Unit
2837
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Hitachi Energy Ltd.
OA Round
1 (Non-Final)
80%
Grant Probability
Favorable
1-2
OA Rounds
3y 2m
To Grant
87%
With Interview

Examiner Intelligence

Grants 80% — above average
80%
Career Allow Rate
364 granted / 454 resolved
+12.2% vs TC avg
Moderate +7% lift
Without
With
+6.6%
Interview Lift
resolved cases with interview
Typical timeline
3y 2m
Avg Prosecution
14 currently pending
Career history
468
Total Applications
across all art units

Statute-Specific Performance

§103
58.7%
+18.7% vs TC avg
§102
27.7%
-12.3% vs TC avg
§112
11.2%
-28.8% vs TC avg
Black line = Tech Center average estimate • Based on career data from 454 resolved cases

Office Action

§103
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Information Disclosure Statement The Information Disclosure Statement (IDS) filed on 02/10/2023, 10/17/2024 and 05/19/2025 have been considered. Claim Objection Claim 9 is objected to for a typo and is interpreted as stating “a set of tap changer contact[s]”. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claims 1-4, 8-16 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Larsson et al., (hereinafter Larsson), U.S. Patent Application Publication 2014/0034464, in view of Mori et al., (hereinafter Mori), Japanese Patent JP2009010106A. Regarding Claim 1, Larsson teaches (except where italicized), a tap changer (100, Fig. 1) arranged to be connected to a regulating winding (regulating winding 105) of a rated regulation voltage, the tap changer (100) comprising: a diverter switch- (115), a tap selector- (120) and a set of tap changer contacts (130, 135); wherein the tap selector (120) and the diverter switch (115) are encapsulated in a shielding structure (305, 310, Fig. 3a) (“a shielding structure comprising a first and second shielding part according to the above is shown in FIGS. 3a-3c” [0064], “[a] first shielding part 305 is shown, which is arranged to be at the potential of the connected tap 110” [0064], “second shielding part 310 is formed inter alia by the fixed contacts 135. Furthermore, the cables 160, connecting the different fixed contacts 135 to the different taps 110 of the regulating winding 105, also form part of the second shielding part 310. As can be seen in FIG. 3a” [0065]) arranged to shield the tap selector (120) and the diverter switch (115) from an external electrical field (“the first and second shielding parts shield the tap selector 120 from external fields” [0057], “the first shielding part can be arranged to shield at least part of the diverter switch” [0017]), the shielding structure (305, 310) being arranged to be electrically connected to a connected tap (110) (“[a] first shielding part 305 is shown, which is arranged to be at the potential of the connected tap 110” [0064]) of the regulating winding (105). (Larsson: Figs. 1-4b, para. [0017], [0057], [0064], [0065]). Larsson does not explicitly teach, wherein the tap selector and the diverter switch are encapsulated in a shielding structure. However, Mori teaches, wherein the tap selector (not shown, “a tap changer selector is housed below the diverter switch” [0018]) and the diverter switch (3) are encapsulated in a shielding structure (2, 9, 10, 11, “perforated electrostatic shield body 20... first electrostatic shield ring 9... second electrostatic shield ring 10... insulating cylindrical container 2” [0023], “third electrostatic shield ring 11” [0012]). (Mori: Figs. 1-5, machine translation, para. [0012], [0018], [0022], [0023]). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the tap changer of Larsson to include the encapsulating shielding structure of Mori, the motivation being that “electrostatic shield rings 9, 10 and 11 are provided near the metal mounting seats 6 and 7 for mounting the insulating support cylinder 5, which is a part where the electric field concentration is severe, to alleviate the electric field concentration” [0011]. (Mori: Figs. 1-5, machine translation, para. [0011]). Therefore, the limitation of Claim 1 would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention. Regarding Claim 2, the combination of Larsson in view of Mori further teaches, wherein the tap selector (120) is electrically connected to the set of tap changer contacts (130, 135), comprising at least two tap changer contacts (primary and secondary contacts, Fig. 1), at least a part of the tap changer contacts (130, 135) being arranged to be connected to a corresponding tap (a corresponding tap of 110) of the regulating winding (105), wherein the set of tap changer contacts (130, 135) is arranged at an opening (opening between shield 305, 330, Fig. 3a) of the shielding structure (390), and wherein the tap changer contacts (135) are arranged on one side of the tap changer (100, Fig. 3a). (Larsson: Figs. 1-4b, para. [0017], [0057], [0064], [0065]). Regarding Claim 3, the combination of Larsson in view of Mori further teaches, wherein the shielding structure (305, 310) at least partly covers the set of tap changer contacts (135) at the opening (opening between shield 305, 330, Fig. 3a) of the shielding structure. (Larsson: Figs. 1-4b, para. [0017], [0057], [0064], [0065]). Regarding Claim 4, the combination of Larsson in view of Mori further teaches, wherein at least one of the at least two tap changer contacts (130, 135) is covered by the shielding structure. (Larsson: Figs. 3a and 3c, para. [0017], [0057], [0064], [0065]). Regarding Claim 8, the combination of Larsson in view of Mori further teaches, wherein the shielding structure (305, 310) is made of an electrically conducting material (“305 is made from a conducting material” 0093). (Larsson: Figs. 3a and 3c, para. [0017], [0057], [0064], [0065]). Regarding Claim 9, Larsson teaches (except where italicized), a transformer arrangement (Fig. 2) comprising: a transformer (200) having at least one regulating winding (105) of a rated regulation voltage, the at least one regulating winding (105) having taps (110); at least one tap changer (100, Fig. 1), having a shielding structure (305, 310), the at least one tap changer (100, Fig. 1) arranged to be connected to a regulating winding (regulating winding 105) of a rated regulation voltage, each of the at least one tap changer (100) comprising: a diverter switch- (115), a tap selector- (120) and a set of tap changer contact[s] (130, 135); wherein the tap selector (120) and the diverter switch (115) are encapsulated in a shielding structure (305, 310, Fig. 3a) (“a shielding structure comprising a first and second shielding part according to the above is shown in FIGS. 3a-3c” [0064], “[a] first shielding part 305 is shown, which is arranged to be at the potential of the connected tap 110” [0064], “second shielding part 310 is formed inter alia by the fixed contacts 135. Furthermore, the cables 160, connecting the different fixed contacts 135 to the different taps 110 of the regulating winding 105, also form part of the second shielding part 310. As can be seen in FIG. 3a” [0065]) arranged to shield the tap selector (120) and the diverter switch (115) from an external electrical field (“the first and second shielding parts shield the tap selector 120 from external fields” [0057], “the first shielding part can be arranged to shield at least part of the diverter switch” [0017]), the shielding structure (305, 310) being arranged to be electrically connected to a connected tap (110) (“[a] first shielding part 305 is shown, which is arranged to be at the potential of the connected tap 110” [0064]) of the regulating winding (105); and wherein each of the at least one tap changer (100) is electrically connected to a respective regulating winding (105) such that its shielding structure (305, 310) is electrically connected to a connected tap (110) of the respective regulating winding (105). (Larsson: Figs. 1-4b, para. [0017], [0049], [0057], [0064], [0065]). Larsson does not explicitly teach, wherein the tap selector and the diverter switch are encapsulated in a shielding structure. However, Mori teaches, wherein the tap selector (not shown, “a tap changer selector is housed below the diverter switch” [0018]) and the diverter switch (3) are encapsulated in a shielding structure (2, 9, 10, 11, “perforated electrostatic shield body 20... first electrostatic shield ring 9... second electrostatic shield ring 10... insulating cylindrical container 2” [0023], “third electrostatic shield ring 11” [0012]). (Mori: Figs. 1-5, machine translation, para. [0012], [0018], [0022], [0023]). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the tap changer of Larsson to include the encapsulating shielding structure of Mori, the motivation being that “electrostatic shield rings 9, 10 and 11 are provided near the metal mounting seats 6 and 7 for mounting the insulating support cylinder 5, which is a part where the electric field concentration is severe, to alleviate the electric field concentration” [0011]. (Mori: Figs. 1-5, machine translation, para. [0011]). Therefore, the limitation of Claim 9 would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention. Regarding Claim 10 and similarly claim 11, the combination of Larsson in view of Mori further teaches, wherein at least a part of the tap changer contacts of the tap changer is electrically connected to a corresponding tap of the regulating winding (105) via electrically insulated connecting cables (160). (Larsson: Figs. 3a and 3c, para. [0065]). Regarding Claim 12, the combination of Larsson in view of Mori further teaches, wherein at least one of the connecting cables (160) is arranged to dielectrically shield (160 comprises part of shield 310) at least one of the tap changer contacts (135) before connecting with another tap changer contact. (Larsson: Figs. 3a and 3c, para. [0065]). Regarding Claim 13, the combination of Larsson in view of Mori further teaches, wherein the at least one regulating winding (Larsson: 105) is housed in a transformer tank (Larsson: not shown) containing an electrically insulating medium (Larsson: “insulated by air or by air-like gases” [0047]), and wherein the shielding structure (Mori: 2, 9, 10, 11, “perforated electrostatic shield body 20... first electrostatic shield ring 9... second electrostatic shield ring 10... insulating cylindrical container 2” [0023], “third electrostatic shield ring 11” [0012]), encapsulating the at least one tap changer (Mori: LTC [0023]), is arranged on a wall of the transformer tank (Mori: fixed within the transformer tank using a metal top cover that closes the top opening of the insulating cylindrical container” [0003]), the motivation being fixing to the wall would be one of a finite group or choices to attach the tap changer. (Larsson: Figs. 3a and 3c, para. [0047], [0065]), (Mori: Figs. 1-5, machine translation, para. [0012], [0018], [0022], [0023]). Regarding Claim 14, the combination of Larsson in view of Mori further teaches, comprising a Y-coupled transformer (200) having three regulating windings (105) and three tap changers (100), and wherein the three tap changers (100) are encapsulated in one shielding structure (305, 310) electrically connected to a common connected tap (110) of the three regulating windings (105). (Larsson: Figs. 3a and 3c, para. [0049], [0065]). Regarding Claim 15, the combination of Larsson in view of Mori further teaches, wherein the tap selector (120) is electrically connected to the set of tap changer contacts (130, 135), comprising at least two tap changer contacts (primary and secondary contacts, Fig. 1), at least a part of the tap changer contacts (130, 135) being arranged to be connected to a corresponding tap (a corresponding tap of 110) of the regulating winding (105), wherein the set of tap changer contacts (130, 135) is arranged at an opening (opening between shield 305, 330, Fig. 3a) of the shielding structure (390), and wherein the tap changer contacts (135) are arranged on one side of the tap changer (100, Fig. 3a). (Larsson: Figs. 1-4b, para. [0017], [0057], [0064], [0065]). Regarding Claim 16, the combination of Larsson in view of Mori further teaches, wherein the shielding structure (305, 310) at least partly covers the set of tap changer contacts (135) at the opening (opening between shield 305, 330, Fig. 3a) of the shielding structure. (Larsson: Figs. 1-4b, para. [0017], [0057], [0064], [0065]). Regarding Claim 20, the combination of Larsson in view of Mori further teaches, wherein the shielding structure (305, 310) is made of an electrically conducting material (“305 is made from a conducting material” 0093). (Larsson: Figs. 3a and 3c, para. [0017], [0057], [0064], [0065]). Pertinent Prior Art The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Fritsche et al. (DE 102016203106 A1) and SMIT & WILLEM & CO NV (GB 887369 A). Allowable Subject Matter Claims 5-7 and 17-19 are objected to as being dependent upon a rejected base claim, but would be allowable if any of claims 5 and 17 are rewritten in independent form including all of the limitation of the base claims and any intervening claims. Claim 5 recites, inter alia, “…wherein the shielding structure comprises a first compartment and a second compartment, separated by an electrically insulating barrier, and wherein the first compartment comprises a first insulating medium and the diverter switch, and wherein the second compartment comprises a second insulating medium and the tap selector”. (Emphasis added). Claim 17 recites, inter alia, “…wherein the shielding structure comprises a first compartment and a second compartment separated by an electrically insulating barrier and wherein the first compartment comprises a first insulating medium and the diverter switch and wherein the second compartment comprises a second insulating medium and the tap selector”. (Emphasis added). Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to MALCOLM BARNES whose telephone number is (408)918-7512. The examiner can normally be reached M-F 7:30-5:00 pm (PST). Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Shawki Ismail can be reached on 571-272-3985. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit http s://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /MALCOLM BARNES/ Primary Examiner, Art Unit 2837 1/10/2026
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Prosecution Timeline

Feb 10, 2023
Application Filed
Jan 10, 2026
Non-Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
80%
Grant Probability
87%
With Interview (+6.6%)
3y 2m
Median Time to Grant
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