12 Outdoor Cast-Resin Transformers for a U.S. Manufacturing Park

Winley Electric manufactured and delivered 12 three-phase cast-resin dry-type transformers for outdoor power distribution at a U.S. manufacturing park. The order comprised four capacity ratings integrated into a single 12.47 kV to 480Y/277 V distribution network under a tight 45-day lead time.

Project Information	Details
Project Location	Houston, Texas, USA
Application	Outdoor distribution for a manufacturing park
Transformer Type	Three-phase cast-resin dry-type transformer
Quantity	12 units: 4 × 225 kVA, 4 × 300 kVA, 2 × 500 kVA, 2 × 750 kVA
Common Voltage	12,470Y/7,200 V to 480Y/277 V
Frequency	60 Hz
Vector Group	YNyn0
Outdoor Configuration	NEMA 3R coated-steel enclosure with ANSI 61 gray finish
Referenced Requirements	ANSI C57.12.01 and DOE 2016
Production Cycle	45 days

• Outdoor Space Limits: Indoor electrical rooms lacked space, requiring all 12 dry-type transformers to be deployed directly outdoors under severe dust, diurnal temperature swings, and condensation risks.
• Mixed Capacities & Protections: The batch spanned four capacity ratings (225, 300, 500, and 750 kVA) on a single 12.47 kV to 480Y/277 V system, featuring different primary protections (fuses vs. non-fused) and impedance targets per rating.
• Tight Delivery & Consistency: Needed a uniform system layout, familiar operating interfaces, and unit-level traceability across all 12 units—all delivered within a strict 45-day deadline.

• Standardized Core Platform: Built all 12 units on a common system architecture (60 Hz, YNyn0, aluminum windings, Class F insulation, 80°C rise, 95 kV/30 kV BIL) for consistent operation and maintenance.
• Outdoor Environmental Protection: Housed units in rugged NEMA 3R coated-steel enclosures (ANSI 61 gray) equipped with digital temperature controllers and automated 240 V anti-condensation space heaters with humidity control.
• Tailored Capacity Designs: Individually engineered short-circuit impedances (3.2% to 7.55%), enclosure dimensions, and primary fuse schemes per capacity rating while guaranteeing unit-level test traceability within the 45-day cycle.

Prior to production, detailed engineering drawings were prepared for each rating capacity group—clearly defining overall general arrangements (GA), enclosure dimensions, terminal entry locations, and accessory layouts. Once customer approval was locked, these engineering baseline drawings served as the strict benchmark for manufacturing, batch assembly, and final inspection across all 12 units.

With design approvals locked, production was executed under a streamlined 12-unit batch production schedule.

The active assemblies combined vacuum-cast resin coils, high-conductivity aluminum windings, and high-permeability grain-oriented silicon steel cores. Assembled active parts were staged for inspection to verify electrical clearances and clamping torque before enclosure integration.

Active assemblies were mounted on base frames inside NEMA 3R enclosures. While cabinet sizes scaled with capacity, door access geometries, terminal layouts, and grounding networks were standardized across the four ratings to maintain a uniform operational layout.

Auxiliary installations focused on climate controls and instrumentation. Each cabinet integrated 240 V control power transformers, sensors, space heaters, alarm beacons, and digital temperature controllers with standardized wiring logic for power, sensor, and protection circuits.

Completed units were fitted with stainless-steel nameplates, danger labels, padlocks, and lifting lugs. Each nameplate linked the unit’s serial number to its rating, impedance, and enclosure rating, establishing full traceability through final testing and dispatch.

All 12 transformers received individual factory test reports dated January 7 to January 9, 2026.

The reports cover winding resistance, insulation resistance, voltage ratio on all five tap positions, vector-group verification, no-load loss and current, load loss at 120°C, short-circuit impedance, induced overvoltage withstand, applied-voltage withstand, and partial discharge measurements.

Dielectric testing included an induced overvoltage test alongside primary and secondary applied AC withstand tests:

(Note: The 500 kVA units also successfully completed supplemental QC lightning impulse testing.)

Following FAT approval, manufacturing was completed by January 14, 2026, strictly adhering to the 45-day cycle. Each transformer was stretch-wrapped, anchored onto heavy-duty timber skids, and containerized. All 12 units were officially dispatched and shipped to the United States on February 5, 2026.

Winley offers a standard 4–6 week lead time after technical approval, with production updates throughout manufacturing. This 12-unit batch, ranging from 225 to 750 kVA, was engineered, manufactured, tested and packed within a 45-day production cycle.

Four transformer ratings were engineered for one 12.47 kV system, with capacity-specific impedance, primary protection, NEMA 3R enclosures, anti-condensation heaters and monitoring accessories. The equipment was produced to the project’s ANSI C57.12.01 and DOE 2016 requirements.

Operating under ISO 9001 with 100% FAT, unit-level traceability, and optional SGS third-party inspection, Winley backed this project with a 24-month warranty (from B/L), full documentation packages, and 24/7 technical support.