2500kVA Transformer Specs: Weight, Oil Volume & Footprint
is a substantial piece of power-distribution equipment commonly used in factories, mines, utility substations, renewable-energy projects, large commercial facilities, and infrastructure systems.
Its 2500kVA rating tells the electrical engineer how much
apparent power the transformer can supply. It does not, however, provide enough
information to determine the transformer’s physical size, total weight, oil
volume, transport method, or required installation area.
Two transformers with the same 2500kVA capacity can have
noticeably different dimensions and weights because of their primary voltage,
secondary voltage, winding material, tank design, cooling system, impedance,
tap changer, accessories, and applicable technical standard.
This guide explains the electrical specifications of a 2500kVA transformer and provides practical guidance on weight, insulating-oil volume, equipment footprint, foundation design, transportation, installation, and quotation requirements.
What Is a 2500kVA Transformer?
A 2500kVA transformer is rated to transfer 2,500
kilovolt-amperes of apparent power under its specified voltage, frequency,
cooling, temperature-rise, and environmental conditions.
For a three-phase transformer, this capacity may be used to
convert a medium-voltage supply such as 10kV, 20kV, 33kV, or 35kV to a lower
distribution voltage. Depending on the project, the secondary voltage may be
400V, 415V, 480V, 690V, 3.15kV, 6.3kV, 10.5kV, or another customized value.
ZHONGSHAO supplies
for industrial, utility, mining, renewable-energy, and
outdoor distribution applications. Available configurations can be adapted
according to the required voltage ratio, capacity, winding material, impedance,
tap range, cooling method, and project standard.
Does 2500kVA Equal 2500kW?
Not necessarily. Transformer capacity is expressed in kVA,
while the active power used by most equipment is expressed in kW. The
relationship depends on the load power factor:
kW = kVA × power factor
|
Power Factor |
Approximate Active Power from 2500kVA |
|
1.00 |
2,500kW |
|
0.95 |
2,375kW |
|
0.90 |
2,250kW |
|
0.85 |
2,125kW |
|
0.80 |
2,000kW |
For example, a facility with a maximum active load of
2,000kW and a power factor of 0.80 already requires 2,500kVA. In that
situation, the transformer would have no reserve capacity for peak demand,
motor starting, harmonic heating, temporary overload, or future expansion.
Before choosing this rating, the buyer should complete a
realistic demand analysis rather than relying only on the total connected load.
Our guide on
how to calculate transformer capacity
explains the relationship between kW, kVA, power factor, load ratio, motor starting, harmonics, and capacity margin.
ZHONGSHAO 2500kVA Electrical
Specifications
The uploaded ZHONGSHAO product catalog includes 2500kVA
oil-immersed transformer configurations for 10kV, 20kV, and 35kV-class systems.
The following figures are catalog references for electrical comparison.
|
Reference Configuration |
No-Load Loss |
Load Loss at 75°C |
No-Load Current |
Impedance |
|
10kV S13,
2500kVA |
1,600W |
21,200W |
0.40% |
5% |
|
20kV S11,
2500kVA |
2,340W |
22,200W |
0.50% |
6% |
|
35kV, 2500kVA |
2,560W |
19,670W |
0.60% |
6.5% |
These values illustrate why capacity alone cannot define a
complete transformer. Even at the same 2500kVA rating, the voltage class and
design series affect losses, impedance, insulation requirements, tank
construction, and overall dimensions.
The final guaranteed parameters should always come from the approved technical datasheet, general arrangement drawing, routine test report, and purchase contract for the specific transformer.
How Much Does a 2500kVA
Transformer Weigh?
There is no universal weight for every 2500kVA transformer.
The total operating weight includes the magnetic core, windings, insulation,
main tank, insulating liquid, radiators, bushings, tap changer, conservator
where applicable, control cabinet, structural steel, and accessories.
For preliminary planning, published specifications from
another established transformer manufacturer provide useful examples of how
construction affects weight and dimensions. The table below uses 2500kVA data
published by Fuji Electric. These figures are external manufacturer references
and must not be interpreted as guaranteed ZHONGSHAO dimensions.
|
Example Construction |
Reference Voltage |
Dimensions, H × L × W |
Total Weight |
Oil Volume |
Equipment Footprint |
|
Hermetically
sealed |
22/24kV |
2150 × 2450 ×
1450mm |
6,450kg |
1,750L |
Approx.
3.55m² |
|
Hermetically
sealed |
33kV |
2350 × 2450 ×
1450mm |
6,600kg |
1,750L |
Approx.
3.55m² |
|
Open type
with conservator |
22/24kV |
2500 × 2500 ×
1550mm |
6,500kg |
1,800L |
Approx.
3.88m² |
|
Open type
with conservator |
33kV |
2650 × 2600 ×
1600mm |
7,200kg |
1,850L |
Approx.
4.16m² |
The original figures can be reviewed on the
Fuji Electric oil-immersed transformer specification page
.
These examples suggest a planning range of approximately
6.45 to 7.2 tonnes, but a customized 2500kVA transformer can fall outside that
range. A 10kV compact sealed unit may be lighter than a 35kV unit equipped with
a conservator, cable boxes, an on-load tap changer, additional radiators, and
special accessories.
Why Can Two 2500kVA Transformers
Have Different Weights?
The voltage class is one of the main reasons. A higher
primary voltage generally requires greater insulation distances, higher-rated
bushings, additional dielectric materials, and sometimes a larger tank. The
final design must also provide the external air clearances required by the
project specification.
Winding material also affects weight. Copper has greater
density and electrical conductivity, while aluminum is lighter and normally
requires a larger conductor cross-section for an equivalent electrical design.
The total difference depends on the manufacturer’s winding geometry and loss
requirements.
The cooling arrangement can make another substantial
difference. A naturally cooled hermetically sealed transformer may use
corrugated tank walls or radiators, while a larger power-transformer design may
include detachable radiator banks, fans, pumps, conservators, and additional
pipework.
Accessories such as an on-load tap changer, cable boxes, neutral-current transformers, surge arresters, marshalling cabinets, oil-level indicators, pressure-relief devices, Buchholz relays, monitoring sensors, and terminal connectors also increase the final operating and shipping weight.
How Much Oil Does a 2500kVA
Transformer Hold?
The published examples above contain approximately 1,750 to
1,850 liters of insulating oil. This is a useful initial reference, but it is
not a universal oil-volume specification for every 2500kVA transformer.
The required oil volume is influenced by tank shape,
radiator area, conservator design, internal clearances, winding and core
displacement, voltage class, cooling arrangement, and temperature-expansion
allowance.
A sealed corrugated-tank transformer and a conservator-type
transformer can therefore hold different amounts of oil even when their
capacities and voltage ratios are similar.
Oil volume in liters should not be confused with oil weight
in kilograms. The relationship depends on the density of the specified
insulating liquid and its temperature. Mineral oil, natural ester, and
synthetic ester fluids do not necessarily have the same density.
For transportation, foundation loading, lifting, and oil-containment calculations, use the manufacturer’s confirmed oil mass, liquid volume, total operating weight, and shipping weight rather than converting liters with an assumed density.
Transformer Footprint vs.
Required Installation Area
The basic equipment footprint is normally calculated by
multiplying the transformer’s overall length by its overall width. For example,
equipment measuring 2450 × 1450mm occupies a rectangular footprint of
approximately 3.55m².
That figure does not represent the complete substation area
required for installation.
The actual installation envelope must also provide space for
radiator airflow, high-voltage and low-voltage cable termination, bushing
clearances, control-cabinet access, tap-changer operation, oil sampling, valve
operation, inspection, maintenance, fire separation, oil containment, and
eventual transformer replacement.
Detachable radiators, conservators, cable boxes, surge
arresters, busducts, and fences may extend beyond the main tank outline. The
transformer may also require a clear route for a crane, forklift, skidding
system, or hydraulic jacks.
For this reason, civil engineers should never design a
foundation or transformer bay from a generic catalog footprint alone.
Construction should be based on the approved general arrangement drawing for
the final order.
2500kVA Transformer Full-Load
Current
The full-load line current of a three-phase transformer can
be calculated as follows:
Current = 2500 × 1000 ÷ (√3 × line voltage)
|
System Voltage |
Approximate Full-Load Current |
|
10kV |
144.3A |
|
11kV |
131.2A |
|
20kV |
72.2A |
|
35kV |
41.2A |
|
400V |
3,608A |
|
415V |
3,478A |
|
480V |
3,007A |
|
690V |
2,092A |
The low-voltage current is particularly important. A 2500kVA
transformer with a 400V secondary supplies more than 3,600A at full load. This
normally requires a high-current busduct, large busbars, or multiple parallel
cables rather than a single conventional cable connection.
The switchboard, busduct, cables, current transformers,
protection devices, and terminals must be selected according to the continuous
current, ambient temperature, enclosure conditions, short-circuit level, harmonic
current, neutral loading, and applicable engineering standard.
Foundation and Floor-Loading
Requirements
The foundation must support the complete operating
transformer rather than only its dry or shipping weight. For preliminary civil
planning, a 6,500kg transformer placed on a 3.55m² footprint creates an average
static load of approximately 1,830kg per square meter.
That average value is not sufficient for structural design
because the load is transferred through wheels, base channels, support pads, or
jacking points. These concentrated reactions can be significantly higher than
the average surface loading.
The approved drawing should therefore provide the total
operating weight, shipping weight, center of gravity, wheel gauge, base
dimensions, mounting-hole positions, jacking points, and individual support
reactions where required.
Outdoor foundations should also consider drainage,
settlement, seismic loads, wind effects on accessories, oil containment, cable
trenches, grounding conductors, and access for future replacement.
Transport Dimensions May Differ
from Operating Dimensions
A fully assembled 2500kVA transformer may be too large or
too heavy to transport in one piece under certain road, port, bridge, or
site-access restrictions.
The manufacturer may therefore ship the main unit separately
from radiators, conservator, bushings, cable boxes, fans, oil, or other
accessories. The transformer may be shipped fully filled with oil, partially
filled, or drained and filled with dry gas, depending on its construction and
transport plan.
Before arranging freight, confirm the largest shipping
piece, heaviest lifting piece, packed dimensions, total shipment weight, center
of gravity, lifting method, container or flat-rack requirements, and whether insulating
oil is shipped inside the transformer or in separate drums.
The site team must also verify gate width, turning radius,
road capacity, overhead restrictions, crane reach, lifting capacity, unloading
area, and the final movement path from the delivery vehicle to the foundation.
Oil Containment and Environmental
Planning
An oil-filled transformer installation may require a bund,
containment pit, drainage system, fire barrier, oil-water separator, or other
environmental protection measures. The exact design depends on local law,
utility rules, the building or fire code, the insurer’s requirements, and the
project owner’s internal standards.
The containment system should be designed from the confirmed
oil volume of the purchased transformer rather than a generic value found
online.
includes general requirements relevant to
liquid-preservation systems, transportation, tank pressure and leak testing,
condition monitoring, safety, and environmental considerations.
Projects following North American practice may refer to
for general electrical and mechanical requirements
applicable to liquid-immersed distribution, power, and regulating transformers.
Clearances and Insulation
Coordination
The equipment footprint must not be used to determine
electrical clearances. Live terminals and bushings require safe distances from
grounded structures, adjacent phases, walls, fences, cable supports, and other
equipment.
The necessary clearances depend on the transformer’s highest
system voltage, insulation level, impulse withstand requirement, terminal
design, altitude, and applicable standard.
addresses transformer insulation levels, dielectric tests,
and recommended external clearances in air.
For sites above the specified reference altitude, the
manufacturer and system designer should review whether additional external
clearance or insulation coordination is necessary.
Cooling and Loading Conditions
Oil-immersed transformers transfer heat from the windings
and core into the insulating liquid. The heated oil then circulates through the
tank walls or radiator system, where heat is released to the surrounding air.
Natural-oil and natural-air cooling is common for
distribution transformers, while project-specific units may include fans or
other enhanced cooling arrangements.
A 2500kVA nameplate rating applies only under its specified
cooling and environmental conditions. High ambient temperature, restricted
radiator airflow, excessive solar heating, altitude, harmonic currents, and
continuous overload can raise winding and oil temperatures.
provides loading guidance for mineral-oil-immersed
transformers and addresses the relationship between load, ambient conditions,
temperature, thermal ageing, and transformer life.
Factory Acceptance Testing and
Documents
Before shipment, the buyer should compare the manufactured
transformer with the approved technical specification and general arrangement
drawing.
The routine test package commonly covers winding resistance,
voltage ratio, vector group, no-load loss, no-load current, load loss,
impedance voltage, insulation resistance, applied-voltage testing,
induced-voltage testing, and other tests required by the selected standard.
The inspection should also verify the nameplate, overall dimensions,
total weight, oil quantity, radiator arrangement, bushings, tap changer,
accessories, control wiring, paint finish, valves, oil level, packing, and
lifting provisions.
Our
factory acceptance testing guide
explains how buyers can define witness points, review test
reports, record nonconformities, and approve equipment before shipment.
Oil Testing After Installation
The insulating oil is an active part of the transformer’s insulation
and cooling system. Its condition can be affected by moisture, oxidation,
contamination, overheating, arcing, partial discharge, and insulation ageing.
A commissioning oil sample provides a useful baseline for
future comparison. Depending on the project and transformer importance, the
maintenance program may include dielectric-breakdown testing, moisture
analysis, acidity, dissipation factor, interfacial tension, dissolved gas
analysis, and trend monitoring.
Our guide to
transformer oil testing and DGA
explains how oil-quality results and dissolved gases can
help detect developing internal problems.
Information Required for an
Accurate Quotation
An accurate 2500kVA transformer quotation begins with the
electrical requirements. The buyer should provide the primary and secondary
voltages, frequency, number of phases, vector group, tap range, impedance,
insulation level, winding material, permitted losses, temperature rise, and
applicable IEC, IEEE, ANSI, utility, or local standard.
The manufacturer also needs the installation conditions,
including indoor or outdoor location, maximum and minimum ambient temperature,
altitude, humidity, dust, corrosion, salt spray, seismic requirement, and
expected harmonic or nonlinear loads.
The mechanical interface should identify the preferred tank
construction, conservator or sealed design, cooling method, cable-box
requirements, bushing orientation, cable or busduct entry direction, wheel
arrangement, monitoring accessories, sound requirement, fire-safety provisions,
and available installation space.
For shipping and commercial planning, include the quantity,
delivery destination, unloading restrictions, maximum transport dimensions,
maximum lifting weight, required documentation, inspection arrangement, and
requested delivery schedule.
A single-line diagram, site layout, load schedule,
protection study, and proposed transformer-bay drawing can help the engineering
team identify conflicts before production.
Frequently Asked Questions
What is the typical weight of a 2500kVA transformer?
Published oil-immersed examples from Fuji Electric range
from approximately 6,450 to 7,200kg. The final weight of a ZHONGSHAO
transformer must be confirmed from the order-specific technical datasheet and
approved drawing.
How much oil is inside a 2500kVA transformer?
The external manufacturer examples in this article contain
approximately 1,750 to 1,850 liters. Actual oil volume depends on voltage
class, tank shape, radiator system, cooling method, conservator design, and
internal construction.
What is the footprint of a 2500kVA transformer?
The published equipment examples occupy approximately 3.55
to 4.16m² based on their length and width. The complete installation area must
be larger because it needs electrical clearances, radiator airflow, maintenance
access, oil containment, cable space, and replacement access.
How many amps does a 2500kVA transformer supply?
A three-phase 2500kVA transformer supplies approximately 3,608A
at 400V, 3,478A at 415V, 3,007A at 480V, 144.3A at 10kV, and 41.2A at 35kV.
Does a dry-type 2500kVA transformer have an oil volume?
No. A conventional cast resin dry-type transformer uses
solid insulation and air cooling rather than transformer oil. Weight,
dimensions, room ventilation, enclosure size, and fire-safety planning are
therefore evaluated differently.
Can a 2500kVA transformer be customized?
Yes. Voltage ratio, winding material, vector group,
impedance, loss level, tap range, cooling, tank design, terminal arrangement,
accessories, monitoring, paint system, and applicable standards can be adapted
to the project.
Final Thoughts
A 2500kVA rating does not define one fixed transformer size.
Weight, oil volume, and footprint can change significantly according to voltage
level, insulation, winding material, tank design, cooling method, accessories,
and technical standards.
For preliminary planning, a typical oil-immersed 2500kVA
unit may weigh around 6.5 to 7.2 tonnes, hold approximately 1,750 to 1,850
liters of oil, and occupy a basic equipment footprint of around 3.55 to 4.16m².
These values are useful only as external reference examples.
The foundation, transport route, crane plan, oil-containment
system, electrical clearances, and transformer bay should be finalized only
after receiving the manufacturer’s approved general arrangement drawing and
guaranteed technical data.
To receive a project-specific 2500kVA transformer proposal,
send your voltage ratio, load information, installation environment, required
standards, layout limitations, and delivery destination through the ZHONGSHAO
.
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