Oil Immersed Transformer

Your Professional Oil Immersed Transformer Supplier

The company has strong manufacturing capabilities and an efficient marketing system, with products covering 500kV and below ultra-high voltage transformers, 35kV and below dry-type transformers, oil immersed transformers, amorphous alloy transformers, wind and solar storage new energy transformers, prefabricated substations, as well as export series such as single-phase flip type transformers, three-phase transformers, isolation transformers, control transformers, voltage regulators, etc. It can also customize various special transformers such as grounding transformers, arc suppression coils, reactors, rectifier transformers, mining transformers, marine transformers, etc. according to customer needs.

35kv Oil-Immersed Transformer
1. Rated capacity: 3150-31500(KVA). 2. Rated high voltage: 35-38.5KV. 3. Rated low voltage: 3.15-10.5kv. 4. Voltage regulation range and number of tap positions: ±2×2.5. 5. Short circuit impedance

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10kv Oil-Immersed Transformer
Capacity: 30kVA～2500kVA. Voltage: 10kV/0.4kV. Connection: Dyn11. Impedance: 4%

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Three-Phase Oil-Immersed Distribution Transformer
Capacity: 30kVA～2500kVA. Voltage: 6kV～10kV/0.4kV. No-Load Loss: Low loss type. Environment: outdoor -25℃～40℃

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Ultra High Voltage Oil Immersed Power Transformer
Rated Capacity: 100MVA～1000MVA. Voltage Level: 500kV, 750kV, 1000kV. Phase: Three-Phase. Frequency: 50Hz / 60Hz. Voltage Regulation: (OLTC)On-Load Tap Changer

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Why choose us

Certification

The enterprise has obtained system certifications such as ISO9001, ISO14001, ISO45001, SA8000, etc. The 10kV and 35kV distribution transformers and box type substations have successively obtained international certifications such as IEC, UL, TUV, CE, KEMA, GOST, etc.

Sales Market

Our products are not only widely recognized in the Chinese market but are also exported to over 70 countries and regions, including the United States, Europe, Australia, and Southeast Asia.

OEM/ODM

We have a wide range of products, and we will provide technical support according to your actual needs to choose the right product for you.

Oil Immersed Transformer

An oil-immersed transformer (also known as an oil-filled transformer) is a type of distribution transformer or power transformer where the core and windings are submerged in insulating oil inside a sealed tank. The oil serves two key purposes:

Insulation: Preventing electrical discharges between internal components.

Cooling: Dissipating the heat generated by the iron core and windings during operation.

Basic parameters

Primary Voltage Ratings	34.5-19.92/13.8-7.957/13.2-7.62/12.47-7.2, 24.94, 26.25, 33 or others
Secondary Voltage Ratings	480/277V, 400/230V, 380/220V or customized
H.V. Tap Range	± 2×2.5% HV taps or others
Type	Oil immersed distribution transformer
BIL	30/95kV
Standards	IEEE, UL, ISO, IEC, GB
Application	Industrial Power Distribution, Commercial Buildings, Agriculture, Power Distribution Substations
Power Rating	30kVA - 2500kVA
Certificate	ISO, CE, UL, IEEE
Cooling Method	ONAN, ONAN/ONAF, KNAN, KNAN/KNAF
Oil	Mineral Oil or FR3
Operation	Step Down & Step Up

Core Components of an Oil-Immersed Transformer

Component	Function
Magnetic Core	Directs magnetic flux and minimizes losses
Windings (LV & HV)	Conduct electrical energy transformation
Insulating Oil	Provides electrical insulation and thermal dissipation
Tank and Radiators	Contain oil and transfer heat to air
Conservator Tank	Accommodates oil expansion during temperature changes
Breather (Silica Gel)	Removes moisture from air entering the conservator
Buchholz Relay	Detects gas from faults in oil-immersed systems
Pressure Relief Device	Releases excess internal pressure to avoid rupture

Functions of the Insulating Oil

Role	Description
Electrical Insulation	Prevents arcing and flashover between energized parts
Heat Removal	Transfers heat from windings to radiator fins
Moisture Barrier	Keeps cellulose insulation dry and stable
Arc Suppression	Quenches internal discharges or incipient faults

Cooling Methods for Oil-Immersed Transformers

Cooling Type	Description	Typical Applications
ONAN	Oil Natural Air Natural – passive circulation	Small to medium transformers
ONAF	Oil Natural Air Forced – fans assist cooling	Medium transformers
OFAF	Oil Forced Air Forced – oil pumps and fans used	Large power transformers
OFWF	Oil Forced Water Forced – water-cooled radiators	Nuclear, HVDC, heavy industry

Service Environment

Device types: Outdoor type

Type of Voltage Regulation: Off-circuit or On-Ioad

Tapping Range: ±5 % ±2x2.5 % ±4x2.5 %

Frequency: 50Hz or 60Hz

Phases: Three or single

Connection SymboL: Dyn11,Yyn0 ( or as requested)

Short- circuit Impedance: Standard Impedance

Altiude is not exceeding 1000m,ambient temperature not exceeding 40OC. If it can't meet such conditions,we will modulate parameters in accordance with standard.

Three-Phase Oil-Immersed Distribution Transformer

Certificate

FAQ

Q: How do transformers been shipped?

A: Transformers always been delivered by ship,train or truck for oversea,which with main active body in bulk and accessories in wooden cases.

Q: Can your product be customerized?

A: Considering differences in voltage, frequency and other speciality of transformer product in different countries and regions,our product can be customerized according to your requirements.

Q: Do you offer guarantee for the products?

A: Yes. We offer at least two years guarantee for all of our transformers.

Q: Do you accept FAT(Factory Acceptance Test)?

A: Yes. It's available. We are responsible for each set transformer's testing.

As one of the most professional oil immersed transformer manufacturers and suppliers in China, we're featured by quality products and good service. Please rest assured to wholesale durable oil immersed transformer made in China here from our factory. Customized orders are welcome.

10kV Oil Immersed Distribution Transformer, Ultra High Voltage Oil Immersed Power Transformer, UHV Oil Immersed Power Transformer