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Medium-voltage transformers

VFI three-phase pad-mounted transformers

Eaton’s Cooper Power series three-phase Vacuum Fault Interrupter (VFI) transformer performs double duty in a single, compact and cost-effective package. Combining a conventional pad-mounted transformer with the proven VFI, the unit provides both voltage transformation and transformer/loop overcurrent protection in a design that simplifies installation, reduces costs and requires less real estate.

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Three-phase VFI pad-mounted transformer brochure
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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 fault protection eliminates the need for fuses, reducing outage time and providing better performance
  • Reduces installation, operation and maintenance costs compared to transformer plus separate switchgear
  • Eliminates single-phasing of three-phase loads and associated ferroresonance problems
  • Ideal for applications where conventional equipment doesn’t provide adequate protection or coordination, where aesthetics is important or where space is at a premium
  • Occupies as little as half the space of a conventional set-up while simplifying installation
  • Sealed visible disconnect window allows operators to verify contact position
  • Protects transformer and provides proper coordination with upstream protective device
  • Single-phase initiated gang-trip for single-phase faults, limiting outage scope in large residential areas
  • FR3 fire-resistant dielectric fluid (optional)

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

A unique design that addresses multiple challenges

Eaton's Cooper Power series VFI transformer is ideal for applications where conventional equipment doesn’t provide adequate protection or coordination, where aesthetics is important or where space is at a premium.

Superior protection for multiple applications

Combining a conventional transformer and switchgear in a single, space-saving cabinet, Eaton's compact VFI transformer provides superior protection, coordination and flexibility for indoor or outdoor residential, commercial or industrial applications.

Get unparalleled reliability at a significantly lower cost

Eaton’s combined transformer/switchgear package reduces overall costs and lifecycle expenses, including installation, operation and maintenance.
Specifications

Ratings

Available in kVA range
 45 kVA to 12,000 kVA
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

Layout
 Compartmental type
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 & step-up
Overcurrent protection
 Vacuum Fault Interrupter (VFI)
Motor operator 
 Remote reset of VFI (optional)
Download Links
  • 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 , 24/01/2023)
  • Copper vs. aluminum conductor product aid
    This brochure explains that Eaton’s Cooper Power series aluminum-wound coils use the same thermal, dielectric and mechanical performance requirements as its copper-wound coils and that in pad-mounted and substation designs, aluminum-wound transformers and copper-wound transformers serve their loads equally well.
    (PDF 83 KB , 01/11/2016)
  • Three-phase VFI pad-mounted transformer brochure
    This brochure describes how Eaton's Cooper Power series three-phase VFI pad-mounted transformer does everything a conventional transformer/switchgear package does in one money-saving, space-saving cabinet.
    (PDF 399 KB , 01/11/2016)
  • 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 , 28/04/2023)
  • Pad-mounted transformer fusing philosophies
    The fusing philosophies described in this document have been used for many years to create fuse selection and coordination tables for Eaton's Cooper Power series fuses used in pad-mounted transformer applications.
    (PDF 117 KB , 01/06/2023)
  • VFI transformer vs. switchgear information
    This technical document discusses how a transformer equipped with an integral vacuum fault interrupter (VFI) can be an alternative to a non-VFI transformer in combination with stand-alone switchgear.
    (PDF 57 KB , 01/03/2015)
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