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What is an Oil-Immersed Transformer?
An油入変圧器 is a power transformer that usesinsulating oil (mineral oil or synthetic ester) 両方にとって冷却 そしてelectrical insulation. The core and windings are submerged in oil, which dissipates heat and prevents electrical breakdown.
主要コンポーネント
コア: Laminated silicon steel to reduce eddy current losses.
巻線: Copper or aluminum conductors (HV/LV).
タンク: Sealed steel container filled with oil.
Insulating Oil:
Mineral oil (most common).
Bio-based or synthetic ester (eco-friendly alternatives).
Cooling System:
Radiators/fins (ONAN – Oil Natural Air Natural).
Fans (ONAF – Oil Natural Air Forced).
Protection Devices:
ブッフホルツリレー (gas detection for internal faults).
圧力リリーフバルブ.
Temperature sensors (oil/winding).
Types of Oil-Immersed Transformers
Hermetically Sealed
Fully sealed tank (no oil exposure to air).
No conservator; メンテナンスの手間がかからない.
Conservator-Type
Expansion tank (conservator) with breather to absorb moisture.
Common in large transformers.
Step-Lap Core Design
Reduced no-load losses and noise.
Specialty Types:
Fire-resistant (less-flammable oil).
Underground (コンパクトなデザイン).
利点
✔ 高効率: Oil provides excellent heat dissipation.
✔ Long Lifespan: 適切に維持されている, lasts 25-30 年.
✔ 費用対効果が高い: Lower initial cost than dry-type transformers.
✔ 過負荷容量: Handles temporary overloads better.
短所
✖ Fire Risk: Oil is flammable (requires fireproof barriers).
✖ メンテナンス: Regular oil testing and leak checks needed.
✖ Environmental Concerns: Oil disposal and spill risks.
アプリケーション
Power Distribution: Step-down 11kV/33kV to 400V.
Industrial Plants: 製鉄所, chemical factories.
Renewable Energy: Wind/solar farm substations.
Railways: Traction power supply.
Maintenance Requirements
Oil Testing:
Dielectric strength (>30 kV for mineral oil).
Acidity (<0.1 mg KOH/g).
Moisture content (<20 ppm).
Leak Inspection: Check gaskets, welds, and valves.
Sludge Removal: Clean oil ducts periodically.
規格 & 認証
IEC 60076: 国際規格.
IEEE C57.12.00: North American standards.
ギガバイト/トン 6451: Chinese standards.
Oil-Immersed vs. 乾式変圧器
特徴 | 油入 | 乾式タイプ |
冷却 | 油 | Air/Solid Insulation |
Fire Risk | より高い | より低い |
メンテナンス | More frequent | Minimal |
効率 | Better at high loads | Slightly lower |
Cost | Lower initial cost | より高い |
Purchasing Considerations
容量 (kVA): Match to load requirements.
Voltage Ratio: Input/output voltage levels.
インピーダンス: Typically 4–10% for distribution transformers.
Environment: Indoor/outdoor, 温度, 湿度.
認証: Ensure compliance with local regulations.
よくある質問
Q: Can oil-immersed transformers be used indoors?
あ: はい, but require fireproof vaults and ventilation (NFPA 70 rules).
Q: How often should oil be tested?
あ: Annually for routine checks; after overloads or faults.
Q: Are biodegradable oils reliable?
あ: はい, synthetic esters offer similar performance with lower fire risk.
For acustomized selection, provide:
Load details (kVA, 電圧).
設置環境.
Special requirements (例えば, 低騒音, high efficiency).
