What is an Oil-Immersed Transformer?

What is an Oil-Immersed Transformer?

Anмасляный трансформатор is a power transformer that usesinsulating oil (mineral oil or synthetic ester) for bothохлаждение иelectrical insulation. The core and windings are submerged in oil, which dissipates heat and prevents electrical breakdown.

Key Components

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

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

3. Танк: 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:

• Реле Бухгольца (gas detection for internal faults).

• Pressure relief valve.

• 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 (реставратор) 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).

Преимущества

✔ Высокая эффективность: Oil provides excellent heat dissipation.
✔ Long Lifespan: Правильный уход, lasts 25-30 годы.
✔ Экономичный: Lower initial cost than dry-type transformers.
✔ Перегрузочная способность: Handles temporary overloads better.

Недостатки

✖ Fire Risk: Масло легко воспламеняется (requires fireproof barriers).
✖ Обслуживание: Regular oil testing and leak checks needed.
✖ Environmental Concerns: Oil disposal and spill risks.

Приложения

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

• Industrial Plants: Сталелитейные заводы, chemical factories.

• Renewable Energy: Wind/solar farm substations.

• Railways: Traction power supply.

Maintenance Requirements

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

• МЭК 60076: International standards.

• IEEE C57.12.00: North American standards.

• ГБ/Т 6451: Chinese standards.

Oil-Immersed vs. Трансформаторы сухого типа

Purchasing Considerations

1. Емкость (кВА): Match to load requirements.

2. Коэффициент напряжения: Input/output voltage levels.

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

4. Environment: Indoor/outdoor, температура, влажность.

5. Certifications: Ensure compliance with local regulations.

Часто задаваемые вопросы

вопрос: Can oil-immersed transformers be used indoors?
А: Да, but require fireproof vaults and ventilation (NFPA 70 правила).

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

вопрос: Are biodegradable oils reliable?
А: Да, synthetic esters offer similar performance with lower fire risk.

For acustomized selection, provide:

• Load details (кВА, Напряжение).

• Installation environment.

• Special requirements (например, низкий уровень шума, high efficiency).