630kVA Oil Immersed Transformer: Core Specifications and Performance Parameters You Must Know

In modern power distribution systems, the 630kVA Oil Immersed Transformer is one of the most commonly used medium-capacity transformers. It plays a critical role in converting medium voltage electricity into low voltage for industrial, commercial, and residential power distribution.

 

A 630kVA Oil Immersed Transformer is designed to operate continuously in power networks while maintaining stable voltage output, high efficiency, and reliable insulation performance. Because transformers typically operate 24 hours a day, selecting the correct specifications and performance parameters is essential for ensuring energy efficiency and long-term reliability.

 

Manufacturers such as GNEE Electric, a professional transformer producer with export experience in multiple global markets, design and manufacture distribution transformers that comply with international standards such as IEC and ANSI.

 

Understanding the key parameters of a 630kVA Oil Immersed Transformer helps engineers, procurement managers, and project contractors choose the right transformer for their electrical systems.

 

630kVA oil immersed transformer installed in an outdoor distribution substation

 

 

The electrical specifications define how a transformer operates in a power distribution network. These parameters determine voltage transformation capability, system compatibility, and operational stability.

 

Rated Capacity

The rated capacity of 630kVA represents the maximum apparent power the transformer can safely deliver under standard operating conditions.

 

This capacity level is widely used in:

• industrial facilities
• urban distribution systems
• infrastructure projects
• mining operations

 

Voltage Rating

 

Typical voltage combinations include:

• High voltage: 10kV or 11kV
• Low voltage: 0.4kV

These voltage levels allow the transformer to step down medium voltage electricity from the grid into usable low voltage power.

 

Frequency

Distribution transformers normally operate at:

• 50 Hz
• 60 Hz

The frequency specification depends on the regional power system.

 

Transformer nameplate close-up showing rated voltage and capacity

 

 

Beyond basic specifications, several performance indicators determine the efficiency and reliability of the transformer.

 

No-Load Loss

No-load loss occurs when the transformer is energized but not supplying load. This loss is mainly caused by the magnetization of the transformer core.

 

Lower no-load loss indicates:

• higher energy efficiency
• reduced electricity waste
• lower operating costs

 

Load Loss

Load loss occurs when the transformer supplies power to electrical equipment. It is primarily generated by the resistance of the windings.

Efficient winding design and high-quality copper conductors help minimize load loss.

 

Impedance Voltage

Impedance voltage is an important parameter affecting short-circuit current and voltage regulation. Typical impedance for a 630kVA Oil Immersed Transformer ranges between 4% and 6%.

 

 

Below is a typical parameter table used by many transformer manufacturers.

Parameter	Typical Value
Rated Capacity	630 kVA
High Voltage	10kV / 11kV
Low Voltage	0.4kV
Phase	Three Phase
Frequency	50Hz / 60Hz
Cooling Method	ONAN
Vector Group	Dyn11
Impedance Voltage	4–6%
No-Load Loss	700–1000 W
Load Loss	7000–7600 W
Insulation Class	A
Winding Material	Copper / Aluminum
Oil Type	Mineral Transformer Oil

Actual parameters may vary depending on standards such as S11, S13, or customized transformer designs.

 

 

The cooling system plays a critical role in maintaining transformer performance and preventing overheating.

 

ONAN Cooling Method

Most 630kVA Oil Immersed Transformers adopt the ONAN cooling method, which stands for:

• Oil Natural
• Air Natural

The transformer oil circulates naturally inside the tank to transfer heat from the core and windings to the cooling radiators.

 

Insulation System

Transformer oil also functions as an insulating medium, protecting internal components from electrical breakdown.

Proper insulation design ensures:

• safe operation
• long service life
• stable electrical performance

Radiator cooling fins on transformer oil tank

 

 

Due to its moderate capacity and stable performance, the 630kVA Oil Immersed Transformer is widely used in various power distribution scenarios.

 

Common applications include:

• industrial manufacturing plants
• mining and heavy industry projects
• commercial complexes
• power distribution substations
• infrastructure construction projects

For many utilities and EPC contractors, 630kVA transformers represent a standard capacity widely used in distribution networks.

 

 

Selecting the correct transformer requires considering several technical factors.

 

Key selection criteria include:

voltage requirements

• energy efficiency standards
• transformer loss values
• cooling system design
• installation environment

 

For example, many modern power projects prefer S13 energy-efficient transformers, which offer lower no-load losses compared with traditional S11 models.

Working with experienced manufacturers ensures the transformer meets both technical requirements and long-term operational efficiency goals.

 

 

The 630kVA Oil Immersed Transformer remains one of the most widely used transformers in medium-voltage power distribution systems. Understanding its core specifications-such as voltage rating, cooling method, loss parameters, and impedance-helps engineers and procurement specialists select the right transformer for reliable power delivery.

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If you are looking for a professional manufacturer or need technical support for selecting a 630kVA Oil Immersed Transformer, contact GNEE today for detailed specifications, project consultation, and competitive pricing.

 

👉 Send us your inquiry now and our engineers will help you choose the best transformer solution for your project.