H01F 27/404
Protective devices specially adapted for fluid filled transformers
Official title: {Protective devices specially adapted for fluid filled transformers}
H01F27/404 (Protective devices specially adapted for fluid filled transformers) appears on 101 US grants and 103 published applications in this corpus.
Search patents in H01F- Granted patents
- 101
- Published applications
- 103
- Assignees
- 75
- Inventors
- 287
- Latest grant
- 11 Aug 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 1 | 0 |
| 1977 | 4 | 0 |
| 1978 | 2 | 0 |
| 1979 | 2 | 0 |
| 1980 | 3 | 0 |
| 1981 | 1 | 0 |
| 1982 | 5 | 0 |
| 1983 | 4 | 0 |
| 1984 | 2 | 0 |
| 1985 | 1 | 0 |
| 1986 | 1 | 0 |
| 1987 | 2 | 0 |
| 1988 | 0 | 0 |
| 1989 | 0 | 0 |
| 1990 | 1 | 0 |
| 1991 | 1 | 0 |
| 1992 | 0 | 0 |
| 1993 | 1 | 0 |
| 1994 | 0 | 0 |
| 1995 | 0 | 0 |
| 1996 | 0 | 0 |
| 1997 | 0 | 0 |
| 1998 | 0 | 0 |
| 1999 | 0 | 0 |
| 2000 | 0 | 0 |
| 2001 | 0 | 0 |
| 2002 | 0 | 0 |
| 2003 | 0 | 0 |
| 2004 | 0 | 0 |
| 2005 | 1 | 2 |
| 2006 | 2 | 2 |
| 2007 | 1 | 0 |
| 2008 | 1 | 2 |
| 2009 | 0 | 5 |
| 2010 | 2 | 2 |
| 2011 | 2 | 7 |
| 2012 | 1 | 3 |
| 2013 | 1 | 4 |
| 2014 | 6 | 5 |
| 2015 | 2 | 1 |
| 2016 | 2 | 7 |
| 2017 | 3 | 3 |
| 2018 | 3 | 6 |
| 2019 | 5 | 4 |
| 2020 | 5 | 9 |
| 2021 | 2 | 7 |
| 2022 | 4 | 5 |
| 2023 | 9 | 9 |
| 2024 | 6 | 5 |
| 2025 | 5 | 10 |
| 2026 | 7 | 5 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Recent patents
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- Air-cell rupture diagnosis method and system24 Sep 2026US 2026/0290683 A1Fortune Electric Co., Ltd.
- Distribution transformer system and methods thereof17 Sep 2026US 2026/0279659 A1Ubicquia, Inc.
- Modular power transformers and methods of installing the same18 Jun 2026US 2026/0171304 A1One Power Company
- System and method for monitoring load usage on an electrical transformer28 May 2026US 2026/0146898 A1Eskom Holdings SOC Limited
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Most cited
By later US patents
- Transformer fault detection47US 4,112,737 AMorgan Schaffer Ltd. · 1978
- System for monitoring abnormality of oil-filled electric devices29US 4,402,211 AHitachi, Ltd. · 1983
- Guard for a high voltage electrical terminal bushing28US 4,201,883 A1980
- Casing construction for pole type dielectric containing transformer21US 4,005,341 AR. E. Uptegraff Manufacturing Company · 1977
- Method for determining dissolved gas concentrations in dielectric coolants19US 4,394,635 AGeneral Electric Company · 1983