Transformers & Substations

Three-Phase Pad-Mounted Distribution Transformer

75 – 2500 kVA · 15/25/35 kV class

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Entogo three-phase pad-mounted distribution transformer, dead-front, NEMA 3R enclosureEntogo three-phase pad-mounted distribution transformer, dead-front, NEMA 3R enclosure — view 2

Overview

Three-phase pad-mounted distribution transformer for North-American utility, commercial and industrial service — 75–2500 kVA, 12.47–34.5 kV class primary to 480Y/277 or 208Y/120 secondary, dead-front loop/radial-feed, NEMA 3R. Designed to IEEE C57.12.34 and DOE 10 CFR 431; UL/CSA certifiable.

This three-phase pad-mounted distribution transformer is the North-American form factor for ground-level medium-voltage service: a liquid-filled core-and-coil in a locked, tamper-resistant steel cabinet that sits on a concrete pad with no fence or pole required. Ratings span 75 to 2500 kVA, with 12.47 / 13.8 / 24.94 / 34.5 kV (15 / 25 / 35 kV class) primaries stepping down to 480Y/277, 208Y/120 or 240/120 V secondaries at 60 Hz.

Electrical and mechanical configuration is specified per project — primary and secondary voltage, BIL by class, loop- or radial-feed dead-front bushings (live-front on request), de-energized tap changer, copper or aluminum windings, and mineral-oil or FR3 natural-ester insulation. The core-and-coil meets DOE 10 CFR 431 efficiency, and an amorphous-metal core is available where a utility evaluates no-load losses. Designed and built to IEEE C57.12.34 / .28 and CSA C88, with UL (cULus) / CSA certification available on request.

Key features

  • Designed and built to IEEE C57.12.34 (three-phase pad-mounted) and C57.12.28 (enclosure integrity), 60 Hz — UL (cULus) / CSA certification available on request.
  • DOE 10 CFR 431 efficiency-compliant core-and-coil; low-loss amorphous-metal core optional for loss-evaluated bids.
  • Dead-front, 200 A loadbreak bushing wells for operator-safe switching; loop-feed (6 bushing) or radial-feed (3 bushing) configurations.
  • Tamper-resistant NEMA 3R cabinet, ANSI 70 green powder coat, pad-lockable, per utility security requirements.
  • Mineral oil standard; FR3 natural ester available for fire-safer, biodegradable insulation in urban and indoor-adjacent siting.
  • Copper or aluminum windings; de-energized tap changer (±2 × 2.5 %); configuration specified per project.

FAQ

Common questions

Is the pad-mounted transformer DOE 2016 (10 CFR 431) efficiency compliant?
Yes. The core-and-coil is designed to meet the U.S. DOE 10 CFR 431 minimum efficiency requirements for liquid-immersed distribution transformers. A low-loss amorphous-metal core is also available where a utility evaluates no-load losses in the bid.
What primary and secondary voltages are available?
Standard North-American primaries are 12.47, 13.2, 13.8 (15 kV class), 24.94 (25 kV class) and 34.5 kV (35 kV class); secondaries are 208Y/120, 480Y/277, 240/120 and 600 V. All units are 60 Hz. Other combinations are built to order.
Is it UL listed or CSA certified?
Units are designed and built to IEEE C57.12.34 / C57.12.28 and CSA C88. UL (cULus) and CSA certification is available on request; certified units ship within a guaranteed 36-week worst case.
Loop-feed or radial-feed — which configuration do I need?
Radial-feed (3 dead-front bushings) suits a single-source tap; loop-feed (6 bushings) lets the unit be fed from either direction and sectionalized, the common choice for underground utility loops. Both are available.

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