심해 방폭
방폭형 전기 응용 분야, 단열재는 고체형과 액체형으로 구분됩니다, 이러한 응용 분야에 맞게 특별히 맞춤화됨, 더 넓은 단열재 카테고리와는 달리.
Solid Insulation Materials
Referred to as “고체 단열재,” 이는 작동 조건 하에서 고체로 유지되는 물질입니다.. 이 카테고리에는 절연 바니시와 같은 재료가 포함됩니다., which are initially liquid but solidify upon application.
Commonly utilized solid insulation materials in explosion-proof electrical equipment are listed below.
| Material grade | Compared to the Tracking Index (CTI) | Material name |
|---|---|---|
| 나 | 600≤CTI | Ceramics (glazed), 운모, 유리 |
| II | 400≤CTI<600 | Melamine asbestos arc plastic, silicone organic asbestos arc resistant plastic, unsaturated polyester aggregate |
| III-a | 175≤CTI＜400 | 폴리테트라플루오로에틸렌 플라스틱, 멜라민 유리 섬유 플라스틱, epoxy glass cloth board treated with arc resistant paint on the surface |
| III-b | 100≤CTI＜175 | Phenolic plastic |
These materials are graded based on their Comparative Tracking Index (CTI), a measure of superficial electrical performance. 하지만, their mechanical, 열의, and chemical properties can vary significantly, necessitating careful selection based on the specific environmental conditions of use, including considerations for mechanical strength, heat resistance, and chemical durability.
Ceramic (Glazed) Materials
Comprising inorganic non-metallic insulation substances, these are formed by sintering metal oxides and non-oxygen metal compounds. Their attributes include a hardness range of 1000~5000HV, tensile strength from 26~36 MPa, compressive strength from 460~680 MPa, melting points exceeding 2000°C, low thermal expansion, and high chemical stability and resistance to corrosion.
Polytetrafluoroethylene (PTFE)
This fluoroplastic material sustains long-term usage across temperatures from -180°C to 260°C. It’s highly chemically stable, resistant to corrosion, exhibits a low friction coefficient, and has a significant thermal expansion coefficient.
Phenolic Plastic
A thermosetting plastic, known commercially as “bakelite” 또는 “phenolic board,” it can withstand temperatures exceeding 3000°C and offers excellent burn resistance and chemical stability, although it is brittle and not resistant to alkali corrosion.
In addition to the solid insulation materials mentioned, explosion-proof electrical equipment extensively utilizes various solid insulating substances, including plastic materials for insulating components and certain auxiliary materials in explosion-proof motors.
Liquid Insulation Materials
These refer to insulating substances typically found in liquid form, like transformer oil, and materials like insulating varnish used for coil impregnation, which solidify after specific treatments yet are still considered liquid insulators.
1. Transformer Oil
• Essential for explosion-proof electrical equipment such as transformers, this oil must meet specific standards:
• Ignition point not below 300°C.
• Flash point not below 200°C (closed cup).
• Kinematic viscosity not exceeding 1*10?? m²/s at 25°C.
• Dielectric breakdown strength at least 27kV.
• Volume resistivity at least 1*10??? m at 25°C.
• Pour point not above -30°C.
• Acidity (neutralization value) up to 0.03 mg/g (potassium hydroxide).
Transformer oil, primarily a mineral insulating oil comprising alkanes, 사이클로알칸, and unsaturated aromatic hydrocarbons, offers excellent insulating qualities and aging stability. 하지만, its use in Class I mining equipment is restricted due to the potential degradation of its insulating properties over prolonged use.
2. Varnish
Utilized for impregnating electrical coils in explosion-proof equipment, insulating varnish improves their electrical insulation capabilities. Available in solvent-based and solvent-free forms, these varnishes are made up of natural or synthetic resins combined with various solvents like benzene and alcohols for the solvent-based type, and synthetic resins, solidifying agents, and active thinners such as styrene for the solvent-free type.
Both types of varnish offer multiple options to suit different application needs, ensuring adaptability to specific operational requirements.