US3496502A - Means for enclosing transformers - Google Patents
Means for enclosing transformers Download PDFInfo
- Publication number
- US3496502A US3496502A US645994A US3496502DA US3496502A US 3496502 A US3496502 A US 3496502A US 645994 A US645994 A US 645994A US 3496502D A US3496502D A US 3496502DA US 3496502 A US3496502 A US 3496502A
- Authority
- US
- United States
- Prior art keywords
- transformer
- enclosure
- transformers
- plate
- casing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F30/00—Fixed transformers not covered by group H01F19/00
- H01F30/06—Fixed transformers not covered by group H01F19/00 characterised by the structure
- H01F30/16—Toroidal transformers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/02—Casings
- H01F27/022—Encapsulation
Definitions
- a transformer generally speaking, is an electrical device which is used to interlink a couple of independent electrical circuits with mangetic flux to affect a change from one voltage to another voltage.
- Various types of transformers are in common used and have been for a great many years.
- Most conventional power transformers comprise coils which are wound around a comparatively straight core portion.
- so-called toroid transformers or those having a coil with a core in the shape of a toroid, are known and are generally accepted as being more efiiecient than the more conventional transformers.
- the rating of a transformer is determined by the rise in temperature of a transformer when delivering a given load. Consequently, more rapid dissipation of heat losses will result in a higher rating for a transformer of any given size. By the same token, more rapid dissipation of heat will allow reduction in size of a transformer having a certain kilovolt-arnpere rating.
- the transformer is merely deposited in an enclosure which is generally open to air flo-w, the air completely surrounding the transformer.
- This arrangement depends on air flow through the device for cooling and may provide sufficient cooling for a relatively short period of time.
- dust and lint accumulate on the transformer and such dust and lint reduce the efliciency of the transformer operation.
- Such enclosures are supposed to be periodically cleaned, 'but because of their construction cleaning is difiicult and as a matter of practice is seldom done.
- This invention relates to transformer enclosures suitable for effecting rapid dissipation of heat from the transformers enclosed therein. More particularly, it relates to such enclosures which are effective for enclosing toroid transformers, and which include air channels open to the atmosphere at each end, which air channels extend through the core of the transformer. Such air channels promote a through fiow of air thus assuring rapid cooling of the transformer.
- the invention provides transformer enclosures wherein the transformers are encased in an encapsulating mateial that aids in the dissipation of heat by transferring heat from the transformer to the exterior surfaces of the transformer enclosure apparatus. Dust does not collect on the transformer because no part of the transformer is exposed to the atmosphere-rather the transformer is entiely surrounded by the encapsulating material.
- the invention also relates to a transformer enclosure apparatus which is air tight and suitable for use in environments which are subject to flooding.
- the invention provides a transformer enclosure which incorporates the advantageous features listed above in combination.
- FIGURE 1 is a top perspective view of a transformer enclosure constructed in accordance with one embodiment of the invention.
- FIGURE 2 is a view taken along the line 2-2 of FIG- URE 1;
- FIGURE 3 is a partial elevational sectional view illustrating one embodiment for connection of the top plate of FIGURE 1;
- FIGURE 4 is a view taken URE 2;
- FIGURE 5 is a view taken along the line 55 of FIG- URE 2;
- FIGURE 6 is an exploded pictorial view illustrating the various parts of the apparatus shown in FIGURE 1, and a transformer suitable for being enclosed in the apparatus;
- FIGURE 7 is a top perspective view of a transformer enclosure constructed in accordance with another embodiment of this invention.
- FIGURE 8 is a view taken along the line 8-8 of FIG- URE 7;
- FIGURE 9 is a graph illustrating core loss by use of a prior art enclosure
- FIGURE 10 is a graph illustrating core loss by use Of another prior art enclosure.
- FIGURE 11 is a graph illustrating core loss using an enclosure of this invention.
- FIGURE 1-6 The embodiments of FIGURE 1-6 Referring now in greater detail to FIGURES 1-6:
- the transformer enclosure apparatus 10 is seen to comprise a shell whi h is suitable for encasing a transformer such as a toroid transformer constructed in accordance with my copending application Ser. No. 466,406, now abandoned.
- the shell is conveniently formed in two parts, a casing 14 of a configuration suitable for surrounding the transformer, and a frame member 12 adapted to matingalong the line 4-4 of FIG- ly fit against the top of the casing 14.
- transformers such as those described in my copending application Ser. No. 466,406.
- transformers are known as toroid transformers because of the shape of the transformer core, and an example of such a transformer is seen pictorially in FIGURE 6.
- the transformer 80 is seen to comprise generally a toroid core 82, and four similar coils 84, 85, 86 and 87 which are equidistantly spaced around the circumference of the core 82.
- the center of each coil is one-quarter revolution, or disposed at an angle of 90, from the center of the two adjacent coils, and one-half revolution, or 180', from the center of the diametrically opposite coil.
- the casing 14 comprises a hollow generally cylindrical body 16 formed about an imaginary central longitudinal axis AA (FIGURE 2), and a stepped bottom portion formed by transverse annular plate 36, longitudinal annular plate 37, and transverse annular plate 24.
- the outer circumferential edge of the annular plate 36 is joined around its entire periphery to the body 16.
- the longitudinal annular plate is joined at the top thereof to the inner circumferential edge of plate 36, and at the bottom thereof to the outer circumferential edge of the plate 24, thereby forming a down step in the bottom of the casing 14.
- Each of said plates are joined around the entire periphery thereof.
- the inner edge of the annular plate 24 (which may be of any suitable configuration such as circular or rectangular, but is square in this embodiment) defines an opening 26 about the central longitudinal axis AA.
- an upstanding duct 28 Joined to the inner edge of the plate 24 around the entire periphery of the opening 26, is an upstanding duct 28 of a transverse cross-sectional configuration similar to that of the opening 26. This duct desirably extends only a short distance upward from the bottom plate 24.
- the top of the casing 14 is open.
- legs 18, 19, 20, and 21 Equidistantly spaced around the circumference of the body portion 16 of the casing 14 (i.e., at one-quarter revolutions around the body) are four legs 18, 19, 20, and 21, which are generally parallel to the longitudinal axis AA and project radially outwardly from the body 16.
- the legs 18, 19, 20, 21 are generally three-sided members opening toward the axis AA, of a size suitable for retaining the coils 84, 85, 86, 87 of the transformer 80.
- the legs are open at the top but are closed at the bottom by a transverse bottom plate 25 which is flush with the bottom plate 24.
- a support rail 22 of [-shape cross section, and attached to the bottom plate beneath the legs 19 and 20 is a support rail 23 which is in this embodiment generally parallel to the rail 22. These rails allow the apparatus to be placed in a level position sufliciently removed from a floor or base 27 to allow air passage underneath the apparatus.
- the frame member 12 is seen to be symmetrical about a central longitudinal axis AA, and may be seen to comprise a generally box-shaped portion having side wall 48, an open top, and a generally open bottom.
- the side wall 48 might be of any suitable configuration such as circular or rectangular, the present embodiment provides a side wall of generally square configuration. It is necessary, of course, that the overall frame member 12 be of such a size and configuration so that it will mate with the casing 14.
- Afiixed to the generally open bottom of the frame 12 are a plurality of radially extending ducts 38, 39, 40
- ducts which converge at a point on the central axis AA of the frame 12.
- These ducts are each closed along the top, bottom and sides thereof but are open at each end to form radial channels 42, 43, 44 and 45 through which air may flow from the atmosphere surrounding the apparatus. Any suitable number of such ducts may be provided.
- a longitudinal duct 34 which in this illustrated embodiment is of square cross-sectional configuration corresponding to the upstanding duct 28 on the bottom of the casing 14. , The top of the duct 34 thus opens into each of the channels 42, 43, 44 and 45.
- outlets 46 and 47 are disposed in the side wall 48 of the frame 12 . These outlets serve as means for placing the primary and secondary leads from the terminals inside the transformer enclosure apparatus to the exterior thereof.
- a conduit 30 which is desirably flexible is placed one end over the upstanding duct 28 and one end over the longitudinal duct 34 to form a longitudinal passageway 32 extending along the central axis AA through the center of the transformer enclosure apparatus 10.
- the conduit 30 should be of a suitable configuration at each end for mating with each of the ducts 28 and 34. In accordance with this embodiment, that configuration is of square cross section. It must be a non-conductor and should fit tightly against each of the ducts 28 and 34, and may desirably be constructed of fibrous material or extruded synthetic polymeric material.
- each of these channels which is open at each end to the atmosphere on the exterior of the apparatus provides a through air draft which promotes cooling of the transformer. As noted above, this is very important to the efficient operation of the transformer, and the cooling provided in this manner is superior to any such cooling available in the prior art.
- the top of frame member 12 is constructed to receive a cover plate 50 suitable for covering the open top of the apparatus.
- a cover plate 50 suitable for covering the open top of the apparatus.
- FIGURE 3 One suitable construction is the embodiment illustrated in FIGURE 3.
- the inner wall ofthe side 48 of frame member 12 includes near the top thereof an annular plate 52 of L-shape cross section which extends around the entire periphery of the side 48.
- One side of the L-shape plate is affixed fiush with the inner wall of side 48 just below the lip thereof as by welding as illustrated by the weld 54.
- the other side of the L-shape plate forms a ledge which extends a short distance from the side 48 toward the central axis A--A.
- This side of the plate 52 has a rim 56 aflixed to the upper part thereof as by welding as illustrated by the weld 58.
- the rim 56 extends upwardly from the plate 52 a distance corresponding to the upward extension of the side 48 above the plate 52, thereby forming a groove 98 suitable for retaining a suitable gasket 66.
- Radially inward-1y from the groove 98, the plate 52 has a hole 60 therein suitable for receiving a bolt.
- the cover plate 50 is of a size and configuration corresponding to the open top of the frame member 12 as determined by the uppermost portions of the wall 48. In the center thereof, it advantageously includes an opening 68 for facilitating entry into the top of the apparatus.
- an opening 68 for facilitating entry into the top of the apparatus.
- transformer enclosures constructed in accordance with this invention are fluid tight and may be used in areas which are susceptible to flooding. This is a distinct advantage and a safety feature which is unavailable with many prior art structures.
- a circular frame member may be provided instead of the specific embodiment of frame member 12 shown here.
- a circular frame member allows use of gaskets which provide greater seal effectiveness.
- an encapsulating material 88 is placed in the interior of the casing 14 completely surrounding the transformer 80 therein, and extending into the lower portion of the frame member 12.
- Terminals 72 and 74 for the primary and secondary coils are supported in the encapsulating material 88 at the upper level of the material.
- Leads 76 and 78 connect the coils with the terminals 72 and 74, respectively, and leads 90 and 92 connect the terminals 72 and 74, respectively, with the exterior of the apparatus through the outlets 47 and 46.
- a fluid-tight chamber 94 void of encapsulating material is provided in the frame member 12, this portion of the apparatus holding the terminals 72 and 74.
- the encapsulating material aids in the transfer of heat from the transformer to the outer surface of the apparatus.
- a large surface area aided by the various air channels through the apparatus, promotes rapid dissipation of heat and consequent eflicient operation of the transformer.
- the assembly of the apparatus may best be understood by reference to FIGURE 6.
- the support rails 22 and 23 are first affixed to the casing 14, and the appropriate interconnections of the leads 76, 78, 90, 92 and terminals 72 and 74 are made on the transformer 80.
- the transformer 80 is then lowered into position in the casing, the coil 84 fitting in the leg 18 of the casing, the coils 85, 86 and 87 fitting in the legs 19, 20 and 21 respectively.
- the bottom of the toroid core 82 rests on the annular plate 36 at the bottom of the casing, as best seen in FIGURE 2.
- the conduit 30 is then affixed to the upstanding duct 28, and the frame 12 is then positioned in place on the casing 14, with the longitudinal duct 34 fitting into the top of the conduit 30.
- the encapsulating material is then introduced into the apparatus.
- Any suitable encapsulating material might be used, one such suitable material being a mixture of about 75% rock aggregate and about 25% polyester or epoxy resin.
- one illustrative example used by applicant is comprised of about 75% rock aggregate and about 25% of the epoxy resin Shell No. 815, which is available from the Shell Chemical Company.
- the rock aggregate is first poured into the apparatus to a level just below the terminals 72 and 74, and the resin is then added, the resin filling the voids between the rock aggregate particles.
- a vacuum is then conveniently drawn in the apparatus to remove air bubbles from the encapsulating material and to guarantee a homogenous mass.
- the edge surfaces on the exterior of the apparatus may then be suitably sealed if desired and the exterior may be painted for esthetic appeal.
- FIGURES 7 and 8 A three-phase transformer enclosure 100 is illustrated in FIGURES 7 and 8, the apparatus resembling in many 6 details the transformer enclosure of the FIGURES l-6 embodiment, and therefore reference may be made to the discussion of that embodiment for details of construction.
- the transformer enclosure apparatus is comprised generally of a longitudinal shell 102 disposed about a central axis B-B.
- the shell 102 is in this instance a one piece structure in contrast with the two piece structure of the enclosure 10 of the FIGURES 1-6 embodiment.
- the shell 102 is comprised generally of a top portion 114, bottom portion 112, a side wall 116 which is wrapped around a major portion of the circumference of the shell, to leave an open side 118.
- the opening along side 118 is covered by a suitably shaped cover plate 104, which is attached to the shell 102 by a connection 138 which may desirably be similar to the connection illustrated in FIG- URE 3.
- the top portion 114 includes along the central longitudinal axis BB a longitudinal duct 122, and the bottom portion 112 includes a similarly shaped upstanding duct 120.
- a suitable conduit 128 similar to the conduit 30 of the FIGURES 1-6 embodiment is attached to the duct 120 at the bottom and the duct 122 at the top. This conduit and these ducts define a longitudinal passageway 108 extending completely through the transformer enclosure along the longitudinal axis BB.
- the bottom of the apparatus may be disposed on suitable support rails such as the rail 106, and suitable outlet means such as the connection may be supplied to provide means for entry of suitable leads to the terminal plate, the terminals being illustrated as at 126.
- three transformers having cores 130, 132, and 134 are stacked longitudinally in the enclosure 100 with their centers located on the axis BB.
- Encapsulating material fills an area surrounding the central axis BB and completely surrounding the transformers throughout the entire longitudinal length of the enclosure 100.
- a side portion 124 of the apparatus adjacent the cover plate 104 is not encompassed with the encapsulating material.
- the material may be conveniently added while the apparatus 100 is positioned on its side 116 opposite the open side 118, and not set upright to the FIGURES 7 and 8 position until after the encapsulating material has hardened.
- an air channel for draft cooling which extends through the transformer core in each instance and is open to the atmosphere at both ends. In this manner, effective cooling of the transformer core is facilitated.
- additional air channels are provided above the transformer generally transverse to the first mentioned channel.
- a transformer enclosure wherein a material is in contact with the transformer which aids in transfer of heat from the transformer to the surface of the transformer enclosure.
- the present apparatus provides great surface area for the dissipation of heat.
- a transformer enclosure is further provided which is fully submersible and waterproof. Therefore, the invention provides a means whereby transformers may be used in environments subject to flooding which is much more economical and much more convenient than anything provided in the prior art.
- Apparatus suitable for enclosing a transformer having a generally toroid core, in a manner to insure rapid dissipation of heat comprising:
- encapsulating material disposed in said shell completely surrounding said transformer, whereby no part of said transformer is exposed to the atmosphere, said encapsulating material being effective to transfer heat from the transformer to the exterior surfaces of said shell;
- a fluid-tight chamber in said shell void of encapsulating material, said chamber having primary and secondary terminals disposed therein;
- outlet means in the surface of said shell for communication of leads into said chamber
- said shell comprises:
- said frame member for mating with said casing, said frame member including said fluid-tight chamber, and
- a cover plate for covering said chamber.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transformer Cooling (AREA)
- Insulating Of Coils (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US64599467A | 1967-06-14 | 1967-06-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3496502A true US3496502A (en) | 1970-02-17 |
Family
ID=24591306
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US645994A Expired - Lifetime US3496502A (en) | 1967-06-14 | 1967-06-14 | Means for enclosing transformers |
Country Status (4)
Country | Link |
---|---|
US (1) | US3496502A (fr) |
BE (1) | BE709412A (fr) |
DE (1) | DE1763101A1 (fr) |
GB (1) | GB1209784A (fr) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2385198A1 (fr) * | 1977-03-21 | 1978-10-20 | Eriez Magnetics | Electro-aimant du type sec enrobe de resine pour remplacements charges de poussieres et de gaz |
US4205289A (en) * | 1978-04-25 | 1980-05-27 | Electric Power Research Institute, Inc. | Vaporization cooled electrical inductive apparatus |
FR2638561A1 (fr) * | 1988-11-03 | 1990-05-04 | Optelec Applic Optique Electro | Transformateur electrique a tores multiples |
US5815059A (en) * | 1991-04-26 | 1998-09-29 | Lockheed Martin Corporation | Coaxial isolation mounting of a toroidal transformer |
WO2013007697A1 (fr) * | 2011-07-08 | 2013-01-17 | Abb Research Ltd | Transformateur en triangle à isolation gazeuse |
US20130088107A1 (en) * | 2011-10-07 | 2013-04-11 | Grundfos Holdings A/S | Suppression coil |
CN103515058A (zh) * | 2013-09-09 | 2014-01-15 | 陕西长岭电子科技有限责任公司 | 一种mil-std-1553b总线用隔离变压器 |
US20160118185A1 (en) * | 2013-05-10 | 2016-04-28 | Tokai Kogyo Co., Ltd. | Reactor and manufacturing method of reactor |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT222638Z2 (it) * | 1991-06-19 | 1995-04-24 | Teca Srl | Contenitore di montaggio per apparecchiature elettriche |
EP3282456B1 (fr) * | 2016-08-12 | 2019-04-17 | ABB Schweiz AG | Transformateur de traction |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2668947A (en) * | 1950-02-16 | 1954-02-09 | Allanson Armature Mfg Company | Convertible transformer |
US2743308A (en) * | 1950-12-19 | 1956-04-24 | Bell Telephone Labor Inc | Housing for electrical apparatus and method of manufacture |
US3024434A (en) * | 1957-09-13 | 1962-03-06 | Gen Electric | Electromagnetic induction apparatus |
US3030597A (en) * | 1958-02-28 | 1962-04-17 | Westinghouse Electric Corp | Insulated electrical apparatus |
US3210701A (en) * | 1962-05-14 | 1965-10-05 | Automatic Elect Lab | Wound toroidal core shell |
US3317796A (en) * | 1964-10-27 | 1967-05-02 | Gen Electric | Cooling arrangement for electrical apparatus |
-
1967
- 1967-06-14 US US645994A patent/US3496502A/en not_active Expired - Lifetime
- 1967-11-28 GB GB54136/67A patent/GB1209784A/en not_active Expired
-
1968
- 1968-01-16 BE BE709412D patent/BE709412A/xx unknown
- 1968-04-03 DE DE19681763101 patent/DE1763101A1/de active Pending
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2668947A (en) * | 1950-02-16 | 1954-02-09 | Allanson Armature Mfg Company | Convertible transformer |
US2743308A (en) * | 1950-12-19 | 1956-04-24 | Bell Telephone Labor Inc | Housing for electrical apparatus and method of manufacture |
US3024434A (en) * | 1957-09-13 | 1962-03-06 | Gen Electric | Electromagnetic induction apparatus |
US3030597A (en) * | 1958-02-28 | 1962-04-17 | Westinghouse Electric Corp | Insulated electrical apparatus |
US3210701A (en) * | 1962-05-14 | 1965-10-05 | Automatic Elect Lab | Wound toroidal core shell |
US3317796A (en) * | 1964-10-27 | 1967-05-02 | Gen Electric | Cooling arrangement for electrical apparatus |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2385198A1 (fr) * | 1977-03-21 | 1978-10-20 | Eriez Magnetics | Electro-aimant du type sec enrobe de resine pour remplacements charges de poussieres et de gaz |
US4205289A (en) * | 1978-04-25 | 1980-05-27 | Electric Power Research Institute, Inc. | Vaporization cooled electrical inductive apparatus |
FR2638561A1 (fr) * | 1988-11-03 | 1990-05-04 | Optelec Applic Optique Electro | Transformateur electrique a tores multiples |
US5815059A (en) * | 1991-04-26 | 1998-09-29 | Lockheed Martin Corporation | Coaxial isolation mounting of a toroidal transformer |
WO2013007697A1 (fr) * | 2011-07-08 | 2013-01-17 | Abb Research Ltd | Transformateur en triangle à isolation gazeuse |
CN103650076A (zh) * | 2011-07-08 | 2014-03-19 | Abb研究有限公司 | 气体绝缘式三角形变压器 |
US9208936B2 (en) | 2011-07-08 | 2015-12-08 | Abb Research Ltd | Gas-insulated delta transformer |
CN103650076B (zh) * | 2011-07-08 | 2016-11-23 | Abb研究有限公司 | 气体绝缘式三角形变压器 |
US20130088107A1 (en) * | 2011-10-07 | 2013-04-11 | Grundfos Holdings A/S | Suppression coil |
US20160118185A1 (en) * | 2013-05-10 | 2016-04-28 | Tokai Kogyo Co., Ltd. | Reactor and manufacturing method of reactor |
US9984813B2 (en) * | 2013-05-10 | 2018-05-29 | Toyota Jidosha Kabushiki Kaisha | Reactor and manufacturing method of reactor |
CN103515058A (zh) * | 2013-09-09 | 2014-01-15 | 陕西长岭电子科技有限责任公司 | 一种mil-std-1553b总线用隔离变压器 |
Also Published As
Publication number | Publication date |
---|---|
GB1209784A (en) | 1970-10-21 |
DE1763101A1 (de) | 1971-08-05 |
BE709412A (fr) | 1968-07-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3496502A (en) | Means for enclosing transformers | |
US4543554A (en) | System for the elimination of radio interference and method for its manufacture | |
US3617966A (en) | Core and coil assembly | |
JPH04129206A (ja) | 薄形変圧器 | |
US2870858A (en) | Noise reduction in transformers | |
US2141141A (en) | Ignition coil | |
JP3482385B2 (ja) | 内燃機関用点火コイル | |
US3621425A (en) | Magnetically streamlined heat sink | |
US1486109A (en) | Electric transformer | |
JPS6223441B2 (fr) | ||
US2976503A (en) | Transformer construction | |
JPS6314419Y2 (fr) | ||
JPH11176647A (ja) | 油入変圧器の輸送及び組立方法 | |
US3173986A (en) | Transformer housing and cord reel assembly | |
JP2005019455A (ja) | 高圧トランス | |
JP3492148B2 (ja) | 外鉄形変圧器 | |
JPS5818268Y2 (ja) | モ−ルド変圧器 | |
US2526706A (en) | Electrical transformer | |
US1557501A (en) | Ignition coil | |
US1477396A (en) | Stationary induction apparatus | |
JPS5821151Y2 (ja) | 油入電器 | |
JP3106646B2 (ja) | 油入電気機器のタンク構造 | |
US1035069A (en) | Transformer. | |
JPH0720902Y2 (ja) | タップ巻線付ガス絶縁変圧器 | |
JPS5831374Y2 (ja) | 油入静止電気機器 |