VFI substation transformers

Primary voltage

Delta or Wye connected 2400-34,500 V

Rating

45-12,000 kVA

Interrupt rating

12.5 kA at 25/35 kV, up to 16 kA at 15 kV (up to 65 kA w/PRCL fusing)

Core features

Resettable characteristics of VFI breaker make restoring three-phase service faster and easier
Three-phase VFI breaker has independent single-phase initiation, but is three-phase mechanically gang-tripped — a trip signal on any phase opens all three phases, eliminating single-phasing of three-phase loads
VFI breaker can be used as a three-phase load break switch
Biodegradable and sustainable FR3 dielectric fluid provides fire safety benefits with a projected lifespan well beyond that of a traditional mineral-oil transformer
Sealed visible disconnect window allows operators to verify contact position
Can be paired with a motor operator for remote resetting of VFI
Available up to 35 kV and 900 A

Watch this video to learn more about Eaton's Vacuum Fault Interrupter (VFI) integrated transformers and other VFI applications.

Double the performance

Combining a conventional distribution transformer with a VFI breaker in a single package enhances reliability and protection. Restore three-phase service faster and easier, while eliminating single-phasing of three-phase loads.

A wider range of protection

Eaton's Cooper Power series VFI substation transformer offers a larger scope of protection than conventional transformer fusing. Up to 35 kV and 900 Amps continuous the VFI transformer provides resettable protection that increases asset uptime and system safety.

The safer, greener choice

Filled with FR3 fluid, VFI transformers offer enhanced fire safety and longer lifespan. They are also friendlier to the environment with a carbon-neutral footprint that is biodegradable, non-toxic and non-hazardous.

Save space and reduce equipment coordination

Close-couple medium-voltage liquid-filled transformers with low and medium-voltage assemblies in a streamlined unit substation design.

Learn more

Specifications

Ratings

Available in kVA range	45kVA to 12,000kVA
Primary configuration	Delta or Wye connected
Primary voltage	2400 V-34,500 V
Secondary voltage	208Y/120 V to 14,400 V
Basic Impulse Level	Up to 150kV

Standards

ANSI/IEEE	C57.12.00 and C57.12.36
CSA	C88-M90
NEMA (sound level)	NEMA TR-1
Third-party approval/recognition	FM Global (Indoor & Outdoor), UL/cUL – available for most ratings

Enclosure

Tamper resistance	Three-point latching and padlock system with recessed penta-head bolts
Enclosure integrity	Meets or exceeds ANSI/IEEE C57.12.28 and C57.12.29 (if stainless construction)
Material	Mild or stainless steel (304L)
Enclosure environment	Indoor and outdoor
Insulating medium	Air

Key features

Distribution transformer	Three-phase substation
Install location	Indoor and outdoor
Power direction	Step-down and step-up
Overcurrent protection	Vacuum Fault Interrupter (VFI)
Motor operator	Remote reset of VFI (optional)

Download Links

Brochures

Commercial and industrial medium-voltage electrical distribution products brochure

This brochure outlines Eaton’s Cooper Power series broad commercial and industrial medium-voltage transformer, switchgear, fuse, sectionalizer, switch, regulator, tool, OEM equipment, cable accessory, lightning arrester, power capacitor and recloser offerings.

(PDF 2 MB , 01/24/2023)
Visible break technology product aid

This brochure describes Eaton's Cooper Power series visible break accessory which offers smart solutions to verify the isolation of internal transformer circuitry.

(PDF 359 KB , 04/28/2023)

Product specification guides

Liquid-filled, medium-voltage AR-VFI unit substation transformer specification

This is a CSI formatted construction guide specification for liquid-filled, medium-voltage AR-VFI unit substation transformers.

(DOCX 322 KB , 02/13/2025)
Liquid-filled, medium-voltage S-VFI unit substation transformer specification

This is a CSI formatted construction guide specification for liquid-filled, medium-voltage S-VFI unit substation transformers.

(DOCX 309 KB , 09/23/2020)
Liquid-filled, medium-voltage unit substation transformer specification

This is a CSI formatted construction guide specification for liquid-filled, medium-voltage unit substation transformers.

(DOCX 309 KB , 02/13/2025)

White papers

Proper evaluation of power factor in rectangular and circular coil small power transformer designs white paper

This paper will explore the differences between rectangular and circular coil designs as they relate to power factor and establish acceptable values for each.

(PDF 214 KB , 05/28/2021)

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