What is an Oil-Immersed Transformer?

What is an Oil-Immersed Transformer?

انمحول مغمور بالزيت is a power transformer that usesinsulating oil (mineral oil or synthetic ester) for bothcooling وelectrical insulation. The core and windings are submerged in oil, which dissipates heat and prevents electrical breakdown.

                          14_副本

Key Components

  1. جوهر: Laminated silicon steel to reduce eddy current losses.

  2. اللفات: Copper or aluminum conductors (HV/LV).

  3. Tank: Sealed steel container filled with oil.

  4. Insulating Oil:

    • Mineral oil (most common).

    • Bio-based or synthetic ester (eco-friendly alternatives).

  5. Cooling System:

    • Radiators/fins (ONAN – Oil Natural Air Natural).

    • Fans (ONAF – Oil Natural Air Forced).

  6. Protection Devices:

    • تتابع بوخهولز (gas detection for internal faults).

    • صمام تخفيف الضغط.

    • Temperature sensors (oil/winding).

Types of Oil-Immersed Transformers

  1. Hermetically Sealed

    • Fully sealed tank (no oil exposure to air).

    • No conservator; low maintenance.

  2. Conservator-Type

    • Expansion tank (conservator) with breather to absorb moisture.

    • Common in large transformers.

  3. Step-Lap Core Design

    • Reduced no-load losses and noise.

  4. Specialty Types:

    • Fire-resistant (less-flammable oil).

    • Underground (compact design).12

المزايا

✔ كفاءة عالية: Oil provides excellent heat dissipation.
✔ Long Lifespan: تمت صيانتها بشكل صحيح, lasts 25-30 سنين.
✔ فعالة من حيث التكلفة: Lower initial cost than dry-type transformers.
✔ سعة التحميل الزائد: Handles temporary overloads better.

العيوب

✖ Fire Risk: الزيت قابل للاشتعال (requires fireproof barriers).
✖ صيانة: Regular oil testing and leak checks needed.
✖ Environmental Concerns: Oil disposal and spill risks.

التطبيقات

  • Power Distribution: Step-down 11kV/33kV to 400V.

  • Industrial Plants: Steel mills, chemical factories.

  • Renewable Energy: Wind/solar farm substations.

  • Railways: Traction power supply.

متطلبات الصيانة

  1. Oil Testing:

    • Dielectric strength (>30 kV for mineral oil).

    • Acidity (<0.1 mg KOH/g).

    • Moisture content (<20 ppm).

  2. Leak Inspection: Check gaskets, welds, and valves.

  3. Sludge Removal: Clean oil ducts periodically.

Standards & Certifications

  • اللجنة الانتخابية المستقلة 60076: International standards.

  • IEEE C57.12.00: North American standards.

  • GB/T 6451: Chinese standards.

Oil-Immersed vs. المحولات من النوع الجاف

ميزة

مغمورة بالزيت

Dry-Type

Cooling

زيت

Air/Solid Insulation

Fire Risk

أعلى

أدنى

صيانة

More frequent

Minimal

كفاءة

Better at high loads

Slightly lower

يكلف

Lower initial cost

أعلى

Purchasing Considerations

  1. سعة (كيلو فولت أمبير): Match to load requirements.

  2. Voltage Ratio: Input/output voltage levels.

  3. Impedance: Typically 4–10% for distribution transformers.

  4. Environment: Indoor/outdoor, درجة حرارة, رطوبة.

  5. Certifications: Ensure compliance with local regulations.

التعليمات

Q: Can oil-immersed transformers be used indoors?
أ: نعم, but require fireproof vaults and ventilation (NFPA 70 قواعد).

Q: How often should oil be tested?
أ: Annually for routine checks; after overloads or faults.

Q: Are biodegradable oils reliable?
أ: نعم, synthetic esters offer similar performance with lower fire risk.

For acustomized selection, provide:

  • Load details (كيلو فولت أمبير, الجهد االكهربى).

  • Installation environment.

  • Special requirements (على سبيل المثال, ضوضاء منخفضة, high efficiency).

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