Product overview

Three-phase pad-mounted transformer

Liquid-filled transformers for utility, commercial and industrial distribution. Select the capacity, voltage, connections and protection package for your project.

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Three-phase pad-mounted transformer interior

Technical Specifications

Ratings and Options

Capacity range: 45–5,000 kVA
Primary voltage options: 3.5–6.9 / 11–36 kV
Secondary voltage range: 100–1,500 V
Construction: Liquid-filled; loop or radial feed
Frequency: 60 Hz; other frequencies by design review
Cooling options: ONAN / KNAN, matched to the insulating fluid
Winding connections: Delta / wye, as specified
Front arrangement: Dead front / live front, by design

Reference Configurations

2,500 kVA reference configuration

FR3-filled, 34.5 kV / 480 V reference design.

Parameter	Reference value
Rated capacity	2,500 kVA
Primary / secondary voltage	34.5 kV / 480Y/277 V
Phase / frequency	Three-phase / 60 Hz
Winding connection	Dyn1
Winding options	Copper or aluminum
Cooling / insulating fluid	KNAN / FR3
Winding temperature rise	65 K
HV tap adjustment	De-energized; ±2 × 2.5%, five positions
BIL, HV / LV	150 / 30 kV
Impedance	5.75%
No-load loss	2,200 W at 20°C
Load loss	14,000 W at 55°C, 100% load
Installation / ambient	Outdoor / -25°C to +40°C
Design / test standards	IEEE C57.12.00 / C57.12.10 / C57.12.90

Reference configurations are illustrative. Final specifications, certification and drawings are confirmed for your project.

Download reference specifications (PDF) ↓

Typical features

No-load tap changer for voltage adjustment.
Oil drain and sampling valves.
Pressure-relief valve and pressure/vacuum gauge.
Liquid-level indicator and temperature gauge.
High- and low-voltage bushings with cable connection provisions.
Bayonet-fuse protection and loadbreak switching.

Configuration options

Mineral oil or less-flammable vegetable fluid; FR3 may be requested.
Radial or loop feed; dead-front or live-front arrangements.
55°C, 65°C, or dual 55/65°C temperature-rise designs.
Copper or aluminum windings, depending on the selected series.
Stainless-steel cabinet and accessory options.
Dual-voltage arrangements and alternative secondary connection layouts.

Protection & enclosure review

Coordinate expulsion and current-limiting fuse protection with the utility specification.
Specify corrosion protection for coastal, humid or industrial locations.

Typical applications

Three-phase pad-mounted transformers for:

Utility distribution
Commercial facilities
Industrial facilities
Renewable energy
Energy storage

A closer look

Inside the enclosure.

Annotated three-phase transformer showing fuses, switch, bushings, gauges and relief valve — Component reference
Labeled component reference.

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Start with ratings, quantity, location and your required date. Mention any confidentiality requirements before sending drawings.

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