Prosecution Insights
Last updated: April 19, 2026
Application No. 17/634,767

A NON-LIQUID IMMERSED TRANSFORMER

Non-Final OA §103
Filed
Feb 11, 2022
Examiner
NGUYEN, TUYEN T
Art Unit
2837
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Hitachi Energy Ltd.
OA Round
4 (Non-Final)
82%
Grant Probability
Favorable
4-5
OA Rounds
2y 9m
To Grant
82%
With Interview

Examiner Intelligence

Grants 82% — above average
82%
Career Allow Rate
1001 granted / 1226 resolved
+13.6% vs TC avg
Minimal +1% lift
Without
With
+0.8%
Interview Lift
resolved cases with interview
Typical timeline
2y 9m
Avg Prosecution
50 currently pending
Career history
1276
Total Applications
across all art units

Statute-Specific Performance

§101
0.1%
-39.9% vs TC avg
§103
54.5%
+14.5% vs TC avg
§102
22.9%
-17.1% vs TC avg
§112
17.7%
-22.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1226 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 . 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, 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. Claim(s) 1-8 and 11-19 is/are rejected under 35 U.S.C. 103 as being unpatentable over Barrieras et al. [EPO 3373314 A1] in view of Navarro [WO 2012/103613 A1]. Regarding claims 1-2, Barrieras et al. discloses a non-liquid immersed transformer comprising: - a magnetic core [110] and a coil winding [115, 120] forming a plurality of winding turns around the magnetic core; and - a cooling system comprising: a heat exchanger [150], a main feeding pipe [127] connected to the heat exchanger for carrying coolant fluid from the heat exchanger; a main return pipe [129] connected to the heat exchanger for carrying coolant fluid to the heat exchanger, and a cooling pipe [125, 130] for the flow of a cooling fluid, the cooling pipe extending at least partly along the coil winding between a first point adjacent to an end of the coil winding, and a second point adjacent to the other end of the coil winding, and wherein the cooling pipe comprises a plurality of convolutions to extend the a path of the cooling fluid between one end of the coil winding and one of the main feeding pipe and the main return pipe [figure 1], wherein the plurality of convolutions comprises at least one spiral or serpentine. Barrieras et al. disclose the instant claimed invention except for the convolutions extend between at least one of the first end of the coil winding and the second end of the coil winding and at least one of the main feeding pipe and the main return pipe. Navarro discloses a cooling system for a transformer [figures 6-8] comprising: - a transformer [1]; and - a cooling system [7] including cooling pipe [6] connected to one end of the transformer and to a heat exchanger [6.2], wherein the cooling system including another cooling pipe [6.1] connected to another end of the transformer and the heat exchanger [6.2, figures 6-8], wherein the other cooling pipe further include spiral tube that have a plurality of convolutions/turns in a path between one end of the transformer and the heat exchanger [figures 6-8]. It would have been an obvious to one having ordinary skill in the art, before the effective filing date of the claimed invention, to use the cooling arrangement of Navarro in Barrieras et al. for the purpose of improving cooling and/or reducing the running temperature rise of the transformer. Regarding claim 3, Barrieras et al. further discloses at least two pluralities of convolutions extending the path of the cooling fluid between each end of the coil winding and the main feeding pipe and the main return pipe, respectively [figures 1 or 2]. Regarding claim 4, Barrieras et al. discloses the coil winding comprises a covering made of insulating material [figure 1, or resin 201 in figure 2], the covering comprising an inlet point and an outlet point for the cooling pipe [figure 2]. Regarding claim 5, Barrieras et al. further discloses the convolutions extend the path between an end of the coil winding and an inlet point and/or and outlet point of the coil covering [figure 2]. Regarding claim 6, Barrieras et al. discloses the cooling pipe is made of insulating dielectric material. Regarding claims 7-8, Barrieras et al. further discloses the use of different type of cooling fluid [dielectric fluid such as silicon fluid, non-flammable fluid, ester fluid such as Midel, Biotemp, Envirotemp, fluorinated fluid such as Novec or Fluorinert or mineral/natural oil. Navarro also use different type of cooling medium such as liquid or gas, comprising water and freon. The specific use of cooling fluid with specific electric conductivity or water would have been an obvious design consideration for the purpose of facilitating different desired/improved cooling. Regarding claim 11, Barrieras et al. discloses the transformer having high voltage winding which could be use in a high voltage environment [transformer]. Regarding claim 12, Barrieras et al. discloses the plurality of convolutions comprises a helical coil [figures 1-2]. Regarding claim 13, Barrieras et al. discloses the coil winding comprises a covering [201, figure 2] comprising an inlet point for the cooling pipe, wherein the cooling pipe is connected to the inlet point and the main feeding pipe, and wherein the plurality of convolutions provided in the cooling pipe between the inlet point and the main feeding pipe [figure 2]. Regarding claims 14-15, Barrieras et al. discloses the coil winding comprises a covering [201, figure 2] comprising an outlet point for the cooling pipe, wherein the cooling pipe is connected to the outlet point and the main return pipe, and wherein the plurality of convolutions provided in the cooling pipe between the outlet point and the main return pipe [figure 2], wherein the covering comprises an inlet point for the cooling pipe, wherein the cooling pipe is connected to the inlet point and the main feeding pipe, wherein the plurality of convolutions comprises a first plurality of convolutions, the cooling pipe further comprising a second plurality of convolutions between the inlet point housing and the main feeding pipe [figures 1-2]. Regarding claims 16-18, Barrieras et al. discloses a non-liquid immersed transformer comprising: - a magnetic core [110] and a coil winding [115, 120] forming a plurality of winding turns around the magnetic core; and - a cooling system comprising: - a heat exchanger [150]; and - a cooling pipe for carrying a flow of cooling fluid between the coil winding and the heat exchanger, wherein the cooling pipe comprises a plurality of convolutions in a path between a first end of the coil winding and the heat exchanger, wherein the cooling system further comprises a main feeding pipe [127], wherein the cooling pipe is fluidly connected to the main feeding pipe, and wherein the plurality of convolutions is between the main feeding pipe and the first end of the coil winding, wherein the plurality of convolutions comprises a first plurality of convolutions, the cooling system further comprising a second plurality of convolutions in a second path between a second end of the coil winding and the heat exchanger [figures 1-2]. Barrieras et al. disclose the instant claimed invention except for the plurality of convolutions is spaced apart from the coil winding along a path of the cooling pipe. Navarro discloses a cooling system for a transformer [figures 6-8] comprising: - a transformer [1]; and - a cooling system [7] including cooling pipe [6] connected to one end of the transformer and to a heat exchanger [6.2, figure 8], wherein the cooling system including another cooling pipe connected to another end of the transformer and the heat exchanger [6.2], wherein the other cooling pipe further include spiral tube that have a plurality of convolutions/turns in a path between one end of the transformer and the heat exchanger [figures 6-8]. It would have been an obvious to one having ordinary skill in the art, before the effective filing date of the claimed invention, to use the cooling arrangement of Navarro in Barrieras et al. for the purpose of improving cooling and/or reducing the running temperature rise of the transformer. Regarding claim 19, Barrieras et al. discloses the cooling system further comprises a main return pipe [129] and the cooling pipe is fluidly connected to the main return pipe, wherein the plurality of convolutions comprises a first plurality of convolutions [figure 2] and the cooling system further comprises a second plurality of convolutions between the main return pipe and a second end of the coil winding [figure 2]. Claim(s) 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Barrieras et al. in view of Wang [CN 2239654 Y]. Barrieras et al. discloses a cooling system for a non-liquid immersed transformer including a magnetic core [110] and a coil winding [115, 120] forming a plurality of winding turns around the magnetic core, the cooling system comprising: a heat exchanger [150]; and a cooling pipe for carrying a flow of cooling fluid between the coil winding and the heat exchanger [figure 1]; wherein the cooling pipe comprises a plurality of convolutions in a path between a first end of the coil winding and the heat exchanger [figures 1-2]. Barrieras et al. disclose the instant claimed invention except for the plurality of convolutions is spaced apart from the coil winding along a path of the cooling pipe. Wang et al. discloses a cooling system for a transformer [figure 1] comprising: - a core [1]; - at least one coil [4, 6] arranged about the core; and - a cooling system including cooling pipes [3, 8, 11, 12] arranged around the at least one coil and core, wherein the cooling system further comprises a plurality of convolutions [7], wherein the plurality of convolutions is spaced apart from the coil winding along a path of the cooling pipe [figure 1]. It would have been an obvious to one having ordinary skill in the art, before the effective filing date of the claimed invention, to use the cooling arrangement of Wang et al. in Barrieras et al. for the purpose of improving cooling and/or reducing the running temperature rise of the transformer. Response to Arguments Applicant’s arguments with respect to claim(s) 1-20 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. Allowable Subject Matter Claims 9-10 objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. The following is a statement of reasons for the indication of allowable subject matter: The prior art of record do not teach or disclose, in the claimed combination thereof, first and second conductive connectors arranged at a first one of the coil winding turn, to electrically connect and inner side of the cooling pipe with the first one of the coil winding turns and the second conductive connector is arranged at another winding turn. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to TUYEN T NGUYEN whose telephone number is (571)272-1996. The examiner can normally be reached Mon - Fri 8:30-5:30. 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 https://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. /TUYEN T NGUYEN/Primary Examiner, Art Unit 2837
Read full office action

Prosecution Timeline

Feb 11, 2022
Application Filed
Nov 29, 2024
Non-Final Rejection — §103
Jan 21, 2025
Response Filed
Apr 18, 2025
Final Rejection — §103
May 27, 2025
Response after Non-Final Action
Jul 07, 2025
Request for Continued Examination
Jul 08, 2025
Response after Non-Final Action
Jul 09, 2025
Non-Final Rejection — §103
Sep 15, 2025
Response Filed
Feb 02, 2026
Request for Continued Examination
Feb 10, 2026
Response after Non-Final Action
Feb 20, 2026
Non-Final Rejection — §103 (current)

Precedent Cases

Applications granted by this same examiner with similar technology

Patent 12603221
IMPROVED LOW-EMI TRANSFORMER
2y 5m to grant Granted Apr 14, 2026
Patent 12597552
Magnetic Device and the Method to Make the Same
2y 5m to grant Granted Apr 07, 2026
Patent 12592633
POWER CONVERSION MODULE AND MAGNETIC DEVICE THEREOF
2y 5m to grant Granted Mar 31, 2026
Patent 12592335
LAMINATED COIL COMPONENT
2y 5m to grant Granted Mar 31, 2026
Patent 12586708
INNOVATIVE PLANAR ELECTROMAGNETIC COMPONENT STRUCTURE
2y 5m to grant Granted Mar 24, 2026
Study what changed to get past this examiner. Based on 5 most recent grants.

AI Strategy Recommendation

Get an AI-powered prosecution strategy using examiner precedents, rejection analysis, and claim mapping.
Powered by AI — typically takes 5-10 seconds

Prosecution Projections

4-5
Expected OA Rounds
82%
Grant Probability
82%
With Interview (+0.8%)
2y 9m
Median Time to Grant
High
PTA Risk
Based on 1226 resolved cases by this examiner. Grant probability derived from career allow rate.

Sign in with your work email

Enter your email to receive a magic link. No password needed.

Personal email addresses (Gmail, Yahoo, etc.) are not accepted.

Free tier: 3 strategy analyses per month