630kVA 10kV/0.4kV Oil Immersed Distribution Transformer

 

The 630kVA 10kV/0.4kV oil immersed transformer is one of the most widely used distribution transformers in commercial, industrial, utility, renewable energy, and infrastructure projects. It is commonly manufactured in S11, S13, and energy-efficient transformer series and is designed to step down medium-voltage power networks to low-voltage distribution systems.

 

A standard 630kVA oil-filled transformer complies with IEC 60076, GB 1094, IEEE C57, and other international standards. It features low no-load loss, stable impedance voltage, reliable insulation performance, and long service life. Typical applications include factories, solar power plants, EV charging stations, commercial buildings, hospitals, mining operations, and rural electrification projects.

 

 

The following table shows the typical specifications of a 630kVA oil immersed distribution transformer.

Item	Standard Value
Rated Capacity	630kVA
High Voltage	10kV / 11kV
Low Voltage	0.4kV
Frequency	50Hz / 60Hz
Phase	Three Phase
Cooling Method	ONAN
Vector Group	Dyn11
Tap Changer	±2×2.5% or ±5% Off-Circuit
Impedance Voltage	4%–6%
No-Load Current	≤1.0%
Insulation Class	Class A
Transformer Oil	Mineral Oil / FR3 Ester Oil
Standard	IEC 60076 / GB 1094
Protection Degree	IP23-IP54 (Optional)

 

Need a quote with your exact voltage, loss limits, and local certification?
Request a customized 630kVA transformer specification sheet (S11/S13/ester oil/sealed type) and receive a firm FOB quotation within 24 hours.

 

Request A Quote

 

Transformer losses directly affect operating costs and energy efficiency.

 

Transformer Type	No-Load Loss	Load Loss
S11-630kVA	980W	6200W
S13-630kVA	760W	5960W
Energy Efficient Type	600–700W	5600–5900W

 

The S13 series can reduce no-load losses by approximately 20–30% compared with conventional S11 transformers, helping users lower electricity consumption throughout the transformer's service life.

 

 

The oil quantity depends on the design, manufacturer, cooling system, and efficiency class.

 

Transformer Type	Oil Capacity
Standard 630kVA	500–650 Liters
Conservator Type	550–700 Liters
Fully Sealed Type	500–650 Liters

 

The insulating oil performs three critical functions:

 

• Electrical insulation
• Heat dissipation
• Arc suppression

 

Regular oil testing helps ensure long-term transformer reliability.

 

Transformer weight varies according to design standards and materials.

 

Component	Weight
Active Part	1200–1600 kg
Transformer Oil	450–650 kg
Tank & Accessories	600–900 kg
Total Weight	2200–3200 kg

 

Transportation planning should always consider both shipping weight and lifting requirements.

 

 

Dimension	Approximate Value
Length	1500–1900 mm
Width	900–1200 mm
Height	1400–1800 mm

 

Actual dimensions may vary depending on voltage level, cooling structure, and customer specifications.

 

 

Commercial Buildings

A 630kVA oil transformer typically powers a 10,000–15,000 m² commercial complex and costs 30–40% less than dry type for outdoor or basement substations.

 

Industrial Plants

It handles motor‑heavy loads with 150% short‑term overload capacity while sitting outdoors, saving valuable factory floor space.

 

Solar Power Projects

The 630kVA unit matches 600–700 kWp solar arrays and its sealed oil construction withstands daily temperature swings and UV exposure in PV farms.

 

EV Charging Stations

One 630kVA oil transformer supports 10–15 DC fast chargers and manages rapid daily load cycling better than dry type due to superior oil heat dissipation.

 

Rural Electrification

Pole‑mounted 630kVA sealed oil transformers supply 300–500 households or irrigation pumps, needing no building and only 5‑year maintenance intervals.
 

 

The fully sealed capsule-type oil conservator prevents oxidation and moisture ingress into transformer oil.

 

A flexible rubber capsule is installed inside the conservator tank. As transformer oil expands during operation, the capsule compresses. When oil cools and contracts, the capsule expands back. This completely isolates the oil from ambient air.

 

• Prevents oxidation
• Prevents moisture absorption
• Reduces maintenance requirements
• Extends transformer service life

 

This construction is standard on many modern S13-M fully sealed transformers.
 

 

 

Dyn11 is the most common vector group for 630kVA distribution transformers.

 

• D = High-voltage winding connected in Delta
• y = Low-voltage winding connected in Star (Wye)
• n = Neutral point available on LV side
• 11 = 30° phase displacement
   

Benefits of Dyn11:
 

• Reduces third harmonic currents
• Provides a stable neutral point
• Allows parallel operation
• Improves power quality

 

The standard impedance voltage for a 630kVA 10kV/0.4kV transformer is typically 4.0% or 4.5%.

 

Impedance voltage represents the percentage of rated primary voltage required to produce full-load current when the secondary winding is short-circuited.

 

With 4% impedance voltage, the theoretical short-circuit current at LV terminals is approximately 25 times rated current.
 

 

Parameter	S11	S13
No-Load Loss	Higher	Lower
Energy Efficiency	Standard	High
Operating Cost	Higher	Lower
Initial Investment	Lower	Higher
Lifecycle Cost	Higher	Lower

For projects with continuous operation and long service life, S13 transformers generally provide better economic returns through reduced energy losses.

 

Ready to order for your EV station, solar farm, or industrial project?
We supply 630kVA oil-immersed transformers with IEC/CE/UL certificates, copper windings as standard, and fast delivery to Africa, Southeast Asia, Middle East, and Europe.
Send your inquiry (quantity, voltage, destination port) to get a volume discount and lead time in one business day

 

Request A Quote

 

Q1: What is the difference between S11 and S13 630kVA transformers?

 

A: S13 reduces no-load loss by approximately 27–30% while providing improved energy efficiency with slightly higher initial investment.

 

Q2: What is the oil capacity of a 630kVA transformer?

 

A: Typically 430–650 kg (approximately 480–730 liters), depending on design and manufacturer.

 

Q3: Can a 630kVA transformer handle EV charging station loads?

 

A: Yes. It can support approximately 10–15 DC fast chargers depending on charger power and demand diversity.

 

Q4: What is the full load current of a 630kVA 10kV/0.4kV transformer?

 

A: LV side ≈ 909A. HV side ≈ 36.4A.

 

Q5: How many houses can a 630kVA transformer supply?

 

A: Approximately 250–300 homes under average demand conditions, or 400–500 homes when diversity factors are applied.

 

Q6: What cooling method is used in 630kVA oil-immersed transformers?

 

A: ONAN (Oil Natural Air Natural).

 

Q7: What is the typical lifespan of a 630kVA oil-immersed transformer?

 

A: Typically 25–30+ years with proper maintenance.

 

Q8: Can 630kVA transformers be used for step-up applications?

 

A: Yes. They are widely used in solar power plants, wind farms, and battery energy storage systems for grid integration.