How Big Is a 1500kVA Oil-Immersed Transformer?

You already have a transformer room, a brick enclosure, or a prefabricated substation "house" in place. Now you need to know: Will a 1500kVA oil-immersed transformer actually fit inside?

 

This is one of the most common questions from electrical engineers and project managers-especially those retrofitting existing sites or working within tight urban footprints.

 

As a professional transformer manufacturer with over 18 years of global export experience, GNEE has helped thousands of clients answer this exact question. The short answer is: a standard 1500kVA ONAN oil-immersed transformer typically measures approximately 2100–2550 mm in length, 1600 mm in width, and 1650–2400 mm in height-but the real story involves much more than just the tank dimensions.

 

In this guide, we will walk you through the exact size of a 1500kVA unit, the clearance space you must add for safety and cooling, and a simple "fit‑check" process to determine whether your housing is ready-or what needs to be modified before placing your order.

 

1500kVA 11kv oil-immersed transformer 

 

 

When we talk about the size of a 1500kVA oil-immersed transformer, we are referring to a three-phase distribution transformer, typically rated at 11 kV / 0.4 kV, with ONAN (Oil Natural Air Natural) cooling. However, dimensions are never one-size-fits-all-they vary by design type, winding material, manufacturer, efficiency class (S11, S13, S20), and cooling configuration.

 

Standard 1500kVA Transformer Dimension Ranges

Parameter	Smallest Reference (ONAN)	Typical Standard (GNEE S11)	Pad‑Mounted Type
Length (mm)	1740	2550	2100
Width (mm)	1020	1600	1600
Height (mm)	1950	2400	1650
Total Weight (approx.)	~3,600 kg	4,300 kg	~4,800 kg
Oil Capacity (approx.)	~650 L	780 L	~800–1000 L

 

Source: GNEE's 1500kVA oil-immersed transformer technical specifications: 2550 × 1600 × 2400 mm, 4,300 kg total weight, 780 kg insulating oil weight.

Other manufacturers report slightly different figures. For example, Hengfengshuai's 11 kV / 0.4 kV 1500kVA ONAN unit has dimensions of approximately 1740 mm × 1020 mm × 1950 mm while Zhongyi Electric quotes an oil capacity of 650 L and a total weight of 2,500 kg. A pad‑mounted 1500kVA transformer designed for outdoor underground distribution comes in at 2100 mm × 1600 mm × 1650 mm and weighs around 4,800 kg.

 

 

Many clients make the same mistake: they measure the 1500kVA oil-immersed transformer shell and assume that if the numbers are smaller than the room, they are ready to install. But the transformer's metal tank is only the beginning. To operate safely, your housing must accommodate much more than just the unit itself.

 

Mandatory Clearance for Ventilation (ONAN Cooling)

A 1500kVA oil-immersed transformer uses natural convection to cool itself-no fans (unless you choose ONAF). Hot oil rises to the radiators at the sides; ambient air must flow freely across these surfaces. If your housing traps the hot air, the transformer will overheat, leading to rapid insulation aging and eventual failure.

 

Standard guidelines recommend:

• Minimum side clearance: 300 mm (1 ft) from walls or obstacles
• Recommended side clearance for 1500kVA: 500–1000 mm, depending on ambient temperature
• Front/rear working space: At least 1 m (3.3 ft) for inspection and maintenance

 

A real‑world installation guide for a 1500 kVA transformer handling over 1000 liters of oil specifies 3 m clearance to other transformers and 7.5 m clearance to combustible surfaces. Industry best practices suggest for transformers rated 1000–5000 kVA, outdoor side clearance of 4.9 ft, front/rear clearance of 8.2 ft, and between‑unit spacing of 8.2–9.8 ft.

 

Floor Loading, Oil Containment, and Access Paths

Your "house" must also support:

• Total weight: For a GNEE 1500kVA unit, 4,300 kg plus oil (another ~700–800 kg). The concrete floor must handle roughly 5,000 kg concentrated weight. A soil bearing pressure of at least 2,500 lb/ft² is typically required.
• Oil containment (bunding): A spill containment basin capable of holding 110% of the full oil volume (approx. 850–1100 liters)
• Door width and height: Must accommodate the transformer's longest dimension (e.g., 2550 mm length). If your door is narrower, you may need to order a disassembled unit for on‑site assembly or use a crane for top‑entry.
• Lifting access: Ceiling clearance for an overhead crane or mobile lift to place the transformer onto its foundation.

 

 

Instead of guessing, follow this simple checklist. GNEE engineers use the same process when advising clients remotely, often with nothing more than a tape measure and a few photos.

Step‑by‑Step Fit Check List

• Measure your housing's internal dimensions (length, width, usable height).
• Subtract clearance buffer-add at least 800 mm to length (front + back clearance) and 300‑500 mm to width (handling and ventilation).
• Check door opening against the transformer's length/width. If the door is smaller, ensure the transformer can be disassembled for passage (GNEE offers knock‑down construction).
• Verify floor capacity-concrete slab thickness should be ≥150 mm with proper reinforcement.
• Plan oil containment-a recessed pit or a raised bund wall around the installation pad.
• Check ceiling clearance-you need lifting room for rigging and enough height to stand the transformer upright if arriving lying down.

 

Use This Quick Reference Dimension Table

To make your planning easier, here is a consolidated reference table based on various manufacturer data. Use it as a starting point-then contact GNEE for a model that matches your specific housing.

Configuration	Length (L) mm	Width (W) mm	Height (H) mm	Total Weight (kg)	Oil Capacity (L)
Compact ONAN (standard Chinese design)	≈1740	≈1020	≈1950	≈3,600	≈650
GNEE Standard S11 ONAN (most common)	2550	1600	2400	4,300	780
Pad‑Mounted Outdoor (low‑profile)	2100	1600	1650	4,800	800‑1000
Larger Radiator (hot climate / ONAF ready)	2700+	1800+	2500+	5,000+	1000+

Pro tip: If your housing is on the smaller side, request custom dimensions from GNEE. By adjusting radiator placement, tank geometry, and cooling fin layout, we can often reduce the footprint without sacrificing performance or safety.

 

 

A 1500kVA oil-immersed transformer typically measures between 1740 mm and 2550 mm in length with a total weight of 4,300–5,000 kg, but the true installation space must include ventilation clearance, maintenance access, oil containment, and lifting room. Guessing leads to costly mistakes-delayed projects, modified housing, or even unsafe installations.

 

Do not leave your installation to chance. Send GNEE the following details for a free fit‑check report within 24 hours:

• Internal dimensions of your housing (length, width, height, door opening)
• Photos of the installation site (room, doorway, access path)
• Your loading and ambient temperature conditions

Request A Quote

 

How much oil does a 1500 kVA transformer hold?

The oil capacity of a 1500 kVA transformer is typically around 1000 to 1200 liters. The exact amount can vary based on the design, construction, and cooling requirements of the specific transformer model.

 

What is the load capacity of a 1500 kVA transformer?

A 1500 kVA transformer can supply up to 1500 kVA of apparent power. For typical loads with 0.85 power factor, this equals approximately 1275.0 kW of real power.

 

What size is a 1500 kVA dry type transformer?

1500 kVA Dry Type Transformer Dimensions
Our 1500 kVA dry type transformers come with customizable dimensions typically ranging from 1700 mm to 1900 mm (length), 1100 mm to 1300 mm (width), and 1800 mm to 2100 mm (height).

 

 

What does 1500 kVA mean?

Essentially, the higher the kVA rating, the more power the generator produces. Kilovolt-amps (kVA) measure the Apparent Power of a generator, while kilowatts (kW) measure the Actual Power. The difference between the two is the Power Factor (PF).