Prosecution Insights
Last updated: April 19, 2026
Application No. 18/721,801

DC CIRCUIT BREAKER

Non-Final OA §103
Filed
Jun 19, 2024
Examiner
COMBER, KEVIN J
Art Unit
2838
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
NexFi Technology Inc.
OA Round
1 (Non-Final)
83%
Grant Probability
Favorable
1-2
OA Rounds
2y 5m
To Grant
94%
With Interview

Examiner Intelligence

Grants 83% — above average
83%
Career Allow Rate
689 granted / 834 resolved
+14.6% vs TC avg
Moderate +11% lift
Without
With
+11.3%
Interview Lift
resolved cases with interview
Typical timeline
2y 5m
Avg Prosecution
33 currently pending
Career history
867
Total Applications
across all art units

Statute-Specific Performance

§101
0.9%
-39.1% vs TC avg
§103
52.5%
+12.5% vs TC avg
§102
25.9%
-14.1% vs TC avg
§112
14.5%
-25.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 834 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 . Claims 1-12 are pending in this application. Priority Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55. Information Disclosure Statement The information disclosure statement(s) (IDS) submitted on 06/19/2024 and 01/29/2025 is/are in compliance with the provisions of 37 C.F.R. § 1.97. Accordingly, the IDS has/have been considered by the examiner. Claim Objections Claim 9 is objected to because of the following informalities: Claim 9 recites the limitation “instead of the linear control” in line 3 of the claim. This appears to mean “The DC circuit breaker according to claim[[ 8]] 1, wherein the semiconductor switch is a gated semiconductor device that performs turning on and off based on a gate voltage; and the switch control unit switches the semiconductor switch from on to off by PWM control for the gate of the gated semiconductor device. Appropriate correction is required. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. 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. The factual inquiries 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. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention. Claim(s) 1-3, 8, 9, and 12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Zhou et al. U.S. Patent Application 2022/0115859 (hereinafter “Zhou”) and further in view of Maitra et al. U.S. Patent Application 2007/0121257 (hereinafter “Maitra”). Regarding claim 1, Zhou teaches a DC circuit breaker (i.e. hybrid arc flash mitigation system 50)(fig.2A) comprising: a first current path (i.e. lines L02 and L04)(fig.2A) having a mechanical switch (i.e. mechanical switching device 210)(fig.2A); a second current path (i.e. lines L12 and L16)(fig.2A) that is connected in parallel to the first current path (implicit) and has a semiconductor switch (i.e. IGBTs 203, 205, 207, and 209)(fig.2A); a one-side main current path (i.e. line L25)(fig.2A) that is connected in series to a load side of a parallel connection part (refer to Node N20)(fig.2A) formed of the first current path and the second current path (implicit) and through which main current passes (implicit); and a switch control unit (i.e. system controller 250)(fig.2A) that performs a breaking switch operation (refer to [0052]), determining that an abnormal accident occurs when at least one of a main current value and a time derivative value of the main current value in the one-side main current path is equal to or greater than a threshold set for each (refer to [0052]); however, Zhou does not teach the breaking switch operation in which the semiconductor switch is switched from off to on and then the mechanical switch is switched from on to off. However, Maitra teaches the breaking switch operation in which the semiconductor switch is switched from off to on and then the mechanical switch is switched from on to off (refer to [0066] and [0068]). It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the breaker of Zhou to include the switch operation of Maitra to provide the advantage of limiting arcing of the mechanical switch. Regarding claim 2, Zhou and Maitra teach the DC circuit breaker according to claim 1, wherein the switch control unit starts the breaking switch operation without waiting for receipt of a tripping signal for the main current from an equipment-side breaking control device (refer to Zhou [0007] and [0051]). Regarding claim 3, Zhou and Maitra teach the DC circuit breaker according to claim 1, wherein the switch control unit is capable of switching the semiconductor switch from on to off after switching the semiconductor switch from off to on in the breaking switch operation, regardless of receipt of a tripping signal from an equipment-side breaking control device (refer to Maitra [0068]). Regarding claim 8, Zhou and Maitra teach the DC circuit breaker according to claim 1, wherein: the semiconductor switch is a gated semiconductor device (refer to Zhou IGBTs 203, 205, 207, and 209)(fig.2A)(refer also to Maitra IGBT 20)(fig.1) that performs turning on and off based on a gate voltage (implicit); and the switch control unit switches the semiconductor switch from on to off by linear control that changes the gate voltage analogously (refer to Maitra [0069]). Regarding claim 9, Zhou and Maitra teach the DC circuit breaker according to claim 8 wherein the switch control unit switches the semiconductor switch from on to off by PWM control for the gate of the gated semiconductor device, instead of the linear control (refer to Maitra [0066]). Regarding claim 12, Zhou and Maitra teach the DC circuit breaker according to claim 1, wherein the DC circuit breaker has an arrester (i.e. Zhou VDR 213 and 215)(fig.2A)(i.e. Maitra MOV 32)(fig.1) connected in parallel to the main circuit (implicit) formed of the series connection part of the parallel connection part and the one-side main current path (implicit). Claim(s) 4 and 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Zhou and Maitra as applied to claim 3 above, and further in view of Lee et al. U.S. Patent Application 2016/0285250 (hereinafter “Lee”). Regarding claim 4, Zhou and Maitra teach the DC circuit breaker according to claim 3; however, they do not teach wherein: the DC circuit breaker has a secondary circuit that is connected in parallel to a main circuit formed of a series connection part of the parallel connection part and the one-side main current path and that has a sub-switch and a sub-resistor connected in series with each other; and the switch control unit maintains the sub-switch in an off state before determining that an abnormal accident occurs, and after determining that the abnormal accident occurs, the switch control unit switches off both the mechanical switch and the semiconductor switch in the breaking switch operation and then switches on the sub-switch. However, Lee teaches wherein: the DC circuit breaker has a secondary circuit (i.e. discharge unit 18)(fig.1) that is connected in parallel to a main circuit (implicit) formed of a series connection part of the parallel connection part and the one-side main current path (implicit) and that has a sub-switch (i.e. mechanical switch 20)(fig.1) and a sub-resistor (i.e. discharge resistor 21)(fig.1) connected in series with each other (implicit); and the switch control unit maintains the sub-switch in an off state before determining that an abnormal accident occurs, and after determining that the abnormal accident occurs, the switch control unit switches off both the mechanical switch and the semiconductor switch in the breaking switch operation and then switches on the sub-switch (refer to [0063] and figure 2). It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the breaker of Zhou and Maitra to include the secondary circuit of Lee to provide the advantage of preventing excess discharge current with the breaker is reclosed (refer to Lee [0054]). Regarding claim 5, Zhou, Maitra, and Lee teach the DC circuit breaker according to claim 4, wherein: the series connection part has an other-side main current path that is connected in series with a DC power source side of the parallel connection part (refer to Lee close/open switch 11)(fig.1), where the main current flows (implicit), and that has an internal disconnector (i.e. Lee close/open switch 11)(fig.1); and the switch control unit maintains the internal disconnector off during a period when the sub-switch is on (refer to Lee [0063] and figure 2). Allowable Subject Matter Claims 6, 7, 10, and 11 are 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 an examiner’s statement of reasons for the indication of allowable subject matter: Claims 6 and 7 indicated as containing allowable subject matter because prior art fails to teach or suggest, either alone or in combination all of the limitations of claim 6, especially wherein the switch control unit switches the mechanical switch back from off to on while maintaining the semiconductor switch on, when at least one of the main current value and the time derivative value, which is a basis for determining the occurrence of an abnormal accident, falls below a threshold set for each during the breaking switch operation. Claim 7 is indicated as containing allowable subject matter based on its dependency on claim 6. Claims 10 and 11 are indicated as containing allowable subject matter because prior art fails to teach or suggest, either alone or in combination all of the limitations of claim 10, especially wherein: a plurality of main circuits, each formed of a series connection part of the parallel connection part and the one-side main current path, is provided with being mutually connected in parallel; and the switch control units of the plurality of main circuits perform the linear control or the PWM control of the semiconductor switches so that the semiconductor switches are not turned off simultaneously in the switch operation of the switching condition of the semiconductor switches. Claim 11 is indicated as containing allowable subject matter based on its dependency on claim 10. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to KEVIN J COMBER whose telephone number is (571)272-6133. The examiner can normally be reached Monday - Friday, 9:00 am - 5:00 pm EST. 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, Thienvu V. Tran can be reached at 571-270-1276. 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. /KEVIN J COMBER/Primary Examiner, Art Unit 2838
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Prosecution Timeline

Jun 19, 2024
Application Filed
Feb 09, 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
83%
Grant Probability
94%
With Interview (+11.3%)
2y 5m
Median Time to Grant
Low
PTA Risk
Based on 834 resolved cases by this examiner. Grant probability derived from career allow rate.

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