JPS6231005B2 - - Google Patents
Info
- Publication number
- JPS6231005B2 JPS6231005B2 JP55027628A JP2762880A JPS6231005B2 JP S6231005 B2 JPS6231005 B2 JP S6231005B2 JP 55027628 A JP55027628 A JP 55027628A JP 2762880 A JP2762880 A JP 2762880A JP S6231005 B2 JPS6231005 B2 JP S6231005B2
- Authority
- JP
- Japan
- Prior art keywords
- parts
- resin
- weight
- resin composition
- resistance
- 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
Links
- 239000011342 resin composition Substances 0.000 claims description 26
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 14
- 239000000843 powder Substances 0.000 claims description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 8
- 239000011353 cycloaliphatic epoxy resin Substances 0.000 claims description 8
- 229920000151 polyglycol Polymers 0.000 claims description 7
- 239000010695 polyglycol Substances 0.000 claims description 7
- 239000000377 silicon dioxide Substances 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 6
- 150000008065 acid anhydrides Chemical class 0.000 claims description 3
- 238000010292 electrical insulation Methods 0.000 claims description 3
- 239000004593 Epoxy Substances 0.000 claims description 2
- 229920005989 resin Polymers 0.000 description 9
- 239000011347 resin Substances 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 6
- 229920001187 thermosetting polymer Polymers 0.000 description 6
- 239000004020 conductor Substances 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 239000012212 insulator Substances 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 230000008646 thermal stress Effects 0.000 description 3
- 238000005336 cracking Methods 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 239000011147 inorganic material Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 229930185605 Bisphenol Natural products 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 229920000459 Nitrile rubber Polymers 0.000 description 1
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 1
- NTXGQCSETZTARF-UHFFFAOYSA-N buta-1,3-diene;prop-2-enenitrile Chemical compound C=CC=C.C=CC#N NTXGQCSETZTARF-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000000806 elastomer Substances 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
Landscapes
- Compositions Of Macromolecular Compounds (AREA)
- Epoxy Resins (AREA)
- Organic Insulating Materials (AREA)
Description
本発明は耐トラツキング性，耐クラツク性を要
求される樹脂モールド電気機器に用いられる電気
絶縁用樹脂組成物に関する。
近年、電気機器はコンパクト化，大容量化する
ために、充電部を絶縁物で包含する樹脂モード電
気機器が開発されている。しかも、これらの電気
機器は汚損湿潤環境や屋外に設置され、絶縁物に
は高電界が印加されている。
従来、前述のような条件下で使用される絶縁物
としては、一般にセラミツクスやガラス等の無機
物材料が用いられていた。しかし、これらの無機
材料は機械強度，作業性，生産性，経済性などに
多くの弱点を保有している。このようなことか
ら、前述の電気機器の充電部を熱硬化性樹脂で包
含する樹脂モールド電気機器が採用されるように
なつた。熱硬化性樹脂は前述の汚損湿潤環境や、
屋外で使用される場合、熱硬化性樹脂表面に導電
物が付着しこの導電物に電界が集中する。そして
電界が集中したところから放電が発生し、ジユー
ル熱で熱硬化性樹脂が熱分解する。このようにし
て、導電物が付着している部分の熱硬化性樹脂が
熱分解によつて炭化導電路を形成し、沿面絶縁破
壊を生じることをトラツキングという。従つて、
樹脂モールド電気機器に使用する熱硬化性樹脂は
耐トラツキング性に優れている樹脂を選定しなけ
ればならない。
一般に化学構造上、環状脂肪族エポキシ樹脂が
耐トラツキング性に優れている。更に耐トラツキ
ング性を向上するために、水和アルミナの無機質
粉末材料を環状脂肪族エポキシ樹脂に多量に充填
している組成物は公知である。ところが、前述の
水和アルミナと環状脂肪族エポキシ樹脂の組成物
は耐トラツキング性が非常に優れているが、引張
り強さ５Kg／mm2、シヤルピー衝撃強さ3.4Kg ｆ
cm／cm2と機械強度が弱く、オリフアント熱衝撃ワ
ツシヤ法の耐クラツク指数が3.5と弱い。
このようなことから、前述の樹脂モールド電気
機器を製作するには、通常電気機器の充電部にま
ず機械強度の強い耐クラツク指数の大きい樹脂組
成物、例えばビスフエノール系エポキシ樹脂にシ
リカ粉末を充填した組成物をモールドする。そし
て、その後前述の耐トラツキング性に優れている
樹脂組成物をモールドする。このような樹脂モー
ルド電気機器は、充電部の温度上昇によつて発生
する熱応力に対して最初にモールドされた機械強
度の強い、耐クラツク指数の大きい樹脂組成物に
よつて前述の熱応力を吸収する。この樹脂組成物
と後者のモールドされた耐トラツキング性の良い
樹脂組成物とは、熱膨張係数が約3.1×10-5／℃
とほぼ等しいために双方の樹脂組成物には熱応力
が発生しない。
以上のようなことから、モールドされた双方の
樹脂組成物にはクラツクが発生せず、耐トラツキ
ング性に優れているものが完成する。ところが、
前述の製造方法は、機械強度の強い耐クラツク指
数の大きい樹脂組成物と耐トラツキング性に優れ
ている樹脂組成物の２段モールドになるために、
製造コストが非常に高価となり生産性を考慮する
と実用化は困難である。
また以上の製造方法とは別に、前述の耐トラツ
キング性に優れている樹脂組成物で外筒をまず製
作する。次にこの外筒の内側に電気機器の充電部
を収納する。そして、この外筒の内側と充電部の
外郭との隙間に熱応力を吸収するための部材、例
えばエラストマや絶縁油を注入するものがある。
ところが、これは界面の接着やクラツク防止、あ
るいは油の漏洩を封止するための特殊な技術を必
要として、長期使用の信頼性に乏しい。
このほかの方法として、前述の耐トラツキング
性に優れている樹脂組成物に、ブタジエンアクリ
ロニトリル共重合体や、ポリグリコール等の可と
う性付与剤を添加して、特に樹脂組成物の耐クラ
ツク性を向上し良好な樹脂モールド電気機器を製
作することが周知化している。この方法は、前述
の２段モールドを必要とせず、非常に生産，経済
性，耐クラツク生に優れている。ところが、これ
らの可とう性付与剤は樹脂組成物中で不均一な分
散や化学的に不安定な状態を呈するために、特に
配合量によつて耐湿性，耐熱性（例えば滲出），
耐クラツク性，耐トラツキング性等に問題を生じ
る。
以上のような樹脂モールド電気機器を製造する
方法での樹脂組成物は、製造コスト，生産性，信
頼性に大きな問題を残しており実用化は困難であ
る。このようなことから、電気機器の充電部を１
段でモールドできて、しかも耐トラツキング性，
耐湿性，耐クラツク性にすぐれている可とう性付
与剤を適量配分した樹脂組成物の開発が強く望ま
れていた。
本発明は例えば、屋外で使用されるモールド変
圧器，PT，CTや真空開閉器、あるいは屋内で使
用されても高湿環境に設置されるモールド電気機
器において、１段作業でモールド出来かつそのモ
ールドした樹脂組成物にクラツクが発生せず、し
かも耐トラツキング性に優れている樹脂モールド
電気機器を実現する電気絶縁用樹脂組成物を提供
することを目的とする。
本発明における樹脂組成物は、環状脂肪族エポ
キシ樹脂に添加されるポリグリコールの配合量を
15〜30重量部とする。そして平均粒子径が6.0〜
9.0ミクロンの水和アルミナ及び粒子径が１〜30
ミクロンのシリカ粉末をそれぞれ等分ずつ混合し
たものを350重量部、前述の樹脂に混合し硬化
剤、硬化促進剤等を添加して電気機器の充電部に
直接モールドしたものである。
以下、本発明の一実施例について説明する。こ
の実施例の樹脂組成物は、エポキシ当量150〜170
ｇ／eqの環状脂肪族エポキシ樹脂100重量部と、
酸無水物系硬化剤100重量部と、硬化促進剤と、
平均粒子径6.0〜9.0ミクロンの水和アルミナ175
重量部と、粒子径１〜30ミクロンのシリカ粉末
175重量部と、ポリグリコール15〜30重量部を配
合する。
その製造方法は次の通りである。
エポキシ樹脂，硬化剤のそれぞれに対して、あ
らかじめ含有水分を除去したシリカ粉末を前述の
配合量の50％づつと水和アルミナを前述の配合量
の50％づつを添加し、それぞれ１時間撹拌し良く
混練する。このあと、これらの混練物をいつしよ
にし、前述の硬化促進剤、ポリグリコールを添加
して約10分撹拌する。その後、これを金型に注入
し、80℃×15時間＋120℃×24時間で前述の組成
物を硬化させた。
性能試験は次のようになつた。耐クラツク性の
測定用試験法はオリフアント熱衝撃ワツシヤー法
（材質は軟鋼を用いる）で行なつた。そして耐ク
ラツク性の測定は、高温側としてオーブン中に30
分、低温側としてドライアイス―アルコール液中
に10分づつの放置をくり返し、各温度差をくり返
し数の増加と共に増大させるようにした。この結
果、クラツク発生するまでのサイクル数と、発生
したクラツク数との積を試料ごとにとり、その総
和を試料総数で除すことによつて、耐クラツク指
数を算出したところ８という高い値を得た。
また耐トラツキング性を傾斜平面試験法（IEC
Pub 587法）によつて4.5KVで測定したところ、
平均のトラツキング破壊時間が40分であつた。
すなわち、これ等の値を前述の環状脂肪族エポ
キシ樹脂にポリグリコールを配合しない樹脂組成
物（以下従来の樹脂組成物という）の試料と比較
すると下表のようで、耐クラツク指数は約２，３
倍向上したことが解る。
The present invention relates to an electrically insulating resin composition used in resin-molded electrical equipment that requires tracking resistance and cracking resistance. 2. Description of the Related Art In recent years, in order to make electrical equipment more compact and to increase capacity, resin mode electrical equipment in which a live part is covered with an insulator has been developed. Furthermore, these electrical devices are installed in dirty, humid environments or outdoors, and high electric fields are applied to their insulators. Conventionally, inorganic materials such as ceramics and glass have been generally used as insulators used under the above conditions. However, these inorganic materials have many weaknesses in mechanical strength, workability, productivity, economy, etc. For this reason, resin-molded electrical equipment, in which the live parts of the electrical equipment described above are covered with thermosetting resin, has come into use. Thermosetting resins are exposed to the aforementioned dirty and humid environments,
When used outdoors, a conductive material adheres to the surface of the thermosetting resin, and an electric field concentrates on this conductive material. Electric discharge occurs where the electric field is concentrated, and the thermosetting resin is thermally decomposed by Joule heat. In this way, the thermosetting resin in the portion to which the conductive material is attached forms a carbonized conductive path through thermal decomposition, causing creeping dielectric breakdown, which is called tracking. Therefore,
The thermosetting resin used in resin-molded electrical equipment must have excellent tracking resistance. Generally, cycloaliphatic epoxy resins have excellent tracking resistance due to their chemical structure. In order to further improve the tracking resistance, compositions are known in which a cycloaliphatic epoxy resin is filled with a large amount of an inorganic powder material of hydrated alumina. However, although the aforementioned composition of hydrated alumina and cycloaliphatic epoxy resin has very good tracking resistance, it has a tensile strength of 5 Kg/mm 2 and a sharpie impact strength of 3.4 Kg f.
The mechanical strength is low at cm/ cm2 , and the crack resistance index of the orifant thermal shock washer method is low at 3.5. For this reason, in order to manufacture the above-mentioned resin-molded electrical equipment, the live parts of the electrical equipment are usually first filled with a resin composition that has strong mechanical strength and a high crack resistance index, such as bisphenol-based epoxy resin, and silica powder. The prepared composition is then molded. Then, the above-mentioned resin composition having excellent tracking resistance is molded. Such resin-molded electrical equipment can overcome the thermal stress caused by the rise in temperature of live parts by first molding a resin composition with high mechanical strength and a high crack resistance index. Absorb. This resin composition and the latter molded resin composition with good tracking resistance have a coefficient of thermal expansion of approximately 3.1×10 -5 /°C.
Since they are almost equal, no thermal stress occurs in both resin compositions. From the above, both molded resin compositions are free from cracks and have excellent tracking resistance. However,
The above-mentioned manufacturing method uses a two-stage mold of a resin composition with strong mechanical strength and a high crack resistance index and a resin composition with excellent tracking resistance.
The manufacturing cost is very high, and it is difficult to put it into practical use when productivity is considered. In addition to the above-described manufacturing method, an outer cylinder is first manufactured using the aforementioned resin composition having excellent tracking resistance. Next, the charging part of the electrical device is housed inside this outer cylinder. There are some in which a member for absorbing thermal stress, such as an elastomer or insulating oil, is injected into the gap between the inside of the outer cylinder and the outer shell of the live part.
However, this requires special techniques for interfacial adhesion, prevention of cracks, and sealing of oil leakage, and is therefore unreliable for long-term use. Another method is to add a flexibility imparting agent such as butadiene acrylonitrile copolymer or polyglycol to the above-mentioned resin composition having excellent tracking resistance to improve the cracking resistance of the resin composition. It has become well known to produce improved and better resin molded electrical equipment. This method does not require the above-mentioned two-stage mold, and is excellent in production, economy, and crack resistance. However, these flexibility-imparting agents exhibit non-uniform dispersion and chemical instability in resin compositions, so depending on the amount blended, moisture resistance, heat resistance (e.g. exudation),
This causes problems in crack resistance, tracking resistance, etc. The resin composition used in the method of manufacturing resin-molded electrical equipment as described above has major problems in manufacturing cost, productivity, and reliability, and is difficult to put into practical use. For this reason, it is recommended that the live parts of electrical equipment be
Can be molded in stages and has tracking resistance.
There has been a strong desire to develop a resin composition containing an appropriate amount of a flexibility-imparting agent that has excellent moisture resistance and crack resistance. The present invention can be used, for example, in molded transformers, PTs, CTs, and vacuum switches used outdoors, or molded electrical equipment installed in high humidity environments even when used indoors, and can be molded in one step. An object of the present invention is to provide a resin composition for electrical insulation which realizes resin-molded electrical equipment which does not cause cracks and has excellent tracking resistance. In the resin composition of the present invention, the amount of polyglycol added to the cycloaliphatic epoxy resin is
The amount should be 15 to 30 parts by weight. And the average particle size is 6.0 ~
9.0 micron hydrated alumina and particle size 1-30
350 parts by weight of a mixture of equal parts of micron silica powder was mixed with the above-mentioned resin, a curing agent, a curing accelerator, etc. were added, and the mixture was directly molded onto the live parts of electrical equipment. An embodiment of the present invention will be described below. The resin composition of this example has an epoxy equivalent of 150 to 170.
100 parts by weight of a cycloaliphatic epoxy resin in g/eq.
100 parts by weight of an acid anhydride curing agent, a curing accelerator,
Hydrated alumina 175 with average particle size 6.0-9.0 microns
Parts by weight and silica powder with a particle size of 1 to 30 microns
175 parts by weight and 15 to 30 parts by weight of polyglycol are blended. The manufacturing method is as follows. To each of the epoxy resin and curing agent, 50% of the above-mentioned amount of silica powder and 50% of the above-mentioned amount of hydrated alumina were added, and each was stirred for 1 hour. Knead well. Thereafter, the kneaded mixture is stirred for about 10 minutes after adding the above-mentioned curing accelerator and polyglycol. Thereafter, this was poured into a mold, and the above-mentioned composition was cured at 80°C for 15 hours + 120°C for 24 hours. The performance test was as follows. The test method for measuring crack resistance was the orifant thermal shock washer method (using mild steel as the material). And the crack resistance measurement was performed in the oven at 30°C as the high temperature side.
The sample was left in the dry ice-alcohol solution for 10 minutes each on the low temperature side, and the temperature difference was increased as the number of repetitions increased. As a result, the crack resistance index was calculated by taking the product of the number of cycles until a crack occurred and the number of cracks that occurred for each sample, and dividing the sum by the total number of samples, and a high value of 8 was obtained. Ta. Tracking resistance was also measured using the inclined plane test method (IEC).
Pub 587 method) at 4.5KV.
The average tracking and destruction time was 40 minutes. That is, when these values are compared with the sample of the aforementioned cycloaliphatic epoxy resin containing no polyglycol (hereinafter referred to as a conventional resin composition), the crack resistance index is approximately 2. 3
I can see that it has doubled.
【表】
そして、本実施例による樹脂組成物は、従来の
樹脂組成物に劣らない耐トラツキング性が得られ
た。
また、本発明の樹脂組成物の成分のうち、シリ
カ粉末の添加量を少なくし水和アルミナ粉末の添
加量を増していくとトラツキング破壊時間は長く
なる。そしてシリカ粉末にかわつて水和アルミナ
粉末の充填量が100％になると、樹脂組成物はエ
ロージヨンを呈する。
以上説明したように、本発明によれば、環状脂
肪族エポキシ樹脂と無機質粉末の充填材とポリグ
リコール15〜30重量部と酸無水物硬化剤を適量配
合したので、１段作業でモールド出来て、しかも
モールド後気相，液相冷熱サイクル試験と耐寒試
験においてクラツクが発生せず、電気特性（例え
ば、耐電圧，誘電率，誘電正接，絶縁低抗）の低
下もなく、耐トラツキング性に優れた電気絶縁用
樹脂組成物が提供できる。[Table] The resin composition according to this example had tracking resistance comparable to that of conventional resin compositions. Further, among the components of the resin composition of the present invention, as the amount of silica powder added is decreased and the amount of hydrated alumina powder added is increased, the tracking failure time becomes longer. When the filling amount of hydrated alumina powder instead of silica powder reaches 100%, the resin composition exhibits erosion. As explained above, according to the present invention, since appropriate amounts of a cycloaliphatic epoxy resin, an inorganic powder filler, 15 to 30 parts by weight of polyglycol, and an acid anhydride curing agent are blended, molding can be performed in one step. Furthermore, after molding, no cracks occur in gas phase or liquid phase thermal cycle tests or cold resistance tests, and there is no decrease in electrical properties (e.g. withstand voltage, dielectric constant, dielectric loss tangent, insulation resistance), and it has excellent tracking resistance. A resin composition for electrical insulation can be provided.
Claims (1)
エポキシ樹脂100重量部と、酸無水物系硬化剤100
重量部と、硬化促進剤と、平均粒子径6.0〜9.0ミ
クロンの水和アルミナ175重量部と、粒子径１〜
30ミクロンのシリカ粉末175重量部と、ポリグリ
コール15〜30重量部を配合したことを特徴とする
電気絶縁用樹脂組成物。1 100 parts by weight of a cycloaliphatic epoxy resin with an epoxy equivalent of 150 to 170 g/eq and 100 parts by weight of an acid anhydride curing agent
parts by weight, a curing accelerator, 175 parts by weight of hydrated alumina with an average particle size of 6.0-9.0 microns, and a particle size of 1-9.0 microns.
A resin composition for electrical insulation, characterized in that it contains 175 parts by weight of 30 micron silica powder and 15 to 30 parts by weight of polyglycol.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2762880A JPS56122824A (en) | 1980-03-05 | 1980-03-05 | Resin composition for electric insulation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2762880A JPS56122824A (en) | 1980-03-05 | 1980-03-05 | Resin composition for electric insulation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS56122824A JPS56122824A (en) | 1981-09-26 |
| JPS6231005B2 true JPS6231005B2 (en) | 1987-07-06 |
Family
ID=12226215
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2762880A Granted JPS56122824A (en) | 1980-03-05 | 1980-03-05 | Resin composition for electric insulation |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS56122824A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0676477B2 (en) * | 1986-07-28 | 1994-09-28 | 東芝ケミカル株式会社 | Sealing resin composition |
| US4999699A (en) * | 1990-03-14 | 1991-03-12 | International Business Machines Corporation | Solder interconnection structure and process for making |
| US5121190A (en) * | 1990-03-14 | 1992-06-09 | International Business Machines Corp. | Solder interconnection structure on organic substrates |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4945995A (en) * | 1972-09-07 | 1974-05-02 |
-
1980
- 1980-03-05 JP JP2762880A patent/JPS56122824A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4945995A (en) * | 1972-09-07 | 1974-05-02 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS56122824A (en) | 1981-09-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Dakin | Application of epoxy resins in electrical apparatus | |
| CA1103383A (en) | Silica-alumina trihydrate filled epoxy castings resistant to arced sf.sub.6 | |
| US3585278A (en) | Electrical bushings having insulating means including a cured elastomer containing mineral oil | |
| WO2008037545A1 (en) | Electrical insulation system based on polybenzoxazine | |
| KR102279438B1 (en) | Epoxy resin composition and transformer comprising the same | |
| Zhang et al. | Partial discharge characteristics of cavities with different appearances and positions in solid insulation | |
| JPS6231005B2 (en) | ||
| US4075524A (en) | Brush shunt connection | |
| US3202947A (en) | Epoxy insulated transformer having tris-beta-chloroethylphosphate and hydrated alumina in the insulation | |
| US4277534A (en) | Electrical insulating composition comprising an epoxy resin, a phenolic resin and a polyvinyl acetal resin in combination | |
| US3488616A (en) | Dry type transformer with improved encapsulating composition | |
| Imai | Polymer Composites for Switchgears | |
| JPS59172516A (en) | Resin composition | |
| JPS6228747Y2 (en) | ||
| Hornak et al. | Effect of nanometric oxides on dielectric and mechanical properties of epoxy resin | |
| JPS58175204A (en) | Electrically insulating composition | |
| JP2755666B2 (en) | Epoxy resin composition | |
| Manley et al. | The application of low-pressure resins to some high-voltage switchgear designs | |
| JP2000281753A (en) | Electrically conductive resin composition for shield | |
| JPH034406A (en) | Resin mold electric equipment for outdoor use | |
| JPH1160908A (en) | Casting type epoxy resin for electric insulation | |
| HALLER et al. | Epoxy composite with hBN fillers compatible with industrial application in electrical equipment | |
| JPH04341711A (en) | Epoxy resin molding | |
| JPH0977847A (en) | Casting epoxy resin composition for electric insulation | |
| Liu et al. | Study on the Effect of Absorbing Moisture of Anhydride Curing Agent on the Dielectric Properties of Epoxy Resin Insulation Materials |