25 KVA Transformer On A Pole-44/0.347 KV | Canada 2025

Streamlined Overhead Power: The Modern Pole Mounted Transformer.

01 General

1.1 Project Description

25 kVA single phase pole mounted transformer was delivered to Canada in 2025. The rated power of the transformer is 25 kVA with ONAN cooling. The high voltage is 44 kV with ±2*2.5% tapping range (NLTC), the low voltage is 0.347 kV, they formed a vector group of Ii6.

The unit is engineered to efficiently step down primary voltage from 44kV to a secondary voltage of 347V, making it suitable for supplying commercial and light industrial loads or serving as a distribution point in residential areas.

A key feature of this transformer is its high insulation integrity, designed to withstand severe electrical stresses. On the high-voltage side, it is equipped with two bushings rated for a 250kV Basic Impulse Level (BIL), ensuring superior protection against lightning strikes and switching surges commonly encountered on overhead lines. The low-voltage side features two bushings with a 30kV BIL rating, complemented by a standardized 4-hole NEMA pad configuration. This common interface guarantees seamless, secure, and compliant connections to downstream switchgear, meters, or secondary distribution cables, streamlining field installation and maintenance.

Constructed with a durable, weatherproof tank and filled with high-performance dielectric fluid, this transformer is built for long-term, maintenance-minimized operation in outdoor environments. Its combination of precise voltage transformation, high surge withstand capability, and standardized connectivity makes it a dependable and essential node in the electrical distribution infrastructure.

1.2 Technical Specification

25 kVA pole mounted transformer specifications type and data sheet

1.3 Drawings

25 kVA pole mounted transformer diagram drawing and size.

02 Manufacturing

2.1 Core

The wound core of SCOTECH pole-mounted transformers is precisely fabricated via CNC continuous winding with high-grade cold-rolled grain-oriented silicon steel, featuring an integrated seamless closed magnetic circuit. Stress is fully eliminated through vacuum annealing, while weather resistance is enhanced by interlayer insulating coatings and epoxy resin impregnation. Compared with traditional laminated cores, it cuts no-load loss by 30%-50%, reduces noise by 7-10dB, boosts mechanical strength by 20% and slashes weight by 15%-20%. Ideal for outdoor extreme working conditions ranging from -40℃ to +60℃, it achieves maintenance-free operation and high reliability, perfectly meeting the energy-saving upgrading needs of distribution networks.

2.2 Winding

Coils of SCOTECH pole-mounted transformers feature a compact concentric structure, with conductors of high-purity oxygen-free copper alloy and dual weather-resistant insulation (Nomex paper + epoxy glass cloth). CNC layered winding and constant-tension epoxy curing boost short-circuit resistance by 25%, with partial discharge ≤5pC. Losses cut by 18%-25%, it withstands -40℃~+155℃, resists moisture/salt spray, and enables 20-year maintenance-free operation for distribution network terminals.

2.3 Final Assembly

SCOTECH pole-mounted transformers adopt a modular assembly process with highly integrated, precisely controlled core workflows. The wound core and concentric coils are pre-assembled into a core assembly, followed by vacuum drying for moisture removal. It is then precisely mated with a custom tank and hermetically sealed via helium mass spectrometry leak detection. Subsequent vacuum oil filling and degassing ensure optimal oil-immersed insulation performance.

2.4 HV Bushing

SCOTECH pole-mounted transformer HV bushing: 34.5KV/250A rating, creepage distance ≥991mm, lightning impulse withstand 250KV. Porcelain housing with three-layer insulation (Teflon + paper tube + epoxy pipe) inside; lower porcelain coated with semiconductor paint. Equipped with brass terminals, PTFE support, NBR seals, and aluminum clamp for tank mounting. Hermetically sealed and weather-resistant, ensuring reliable outdoor high-voltage insulation.

2.5 LV Bushing

Compliant with ANSI-1.2KV/250A standards for pole mounted transformers, the LV Bushing consists of 10 key components: 1 brass connecting terminal, 2 NBR plain gaskets, 1 porcelain insulator, 1 steel spin-grip nut, 1 stainless steel flat washer, 2 brass washers, 3 1/2″ brass hex nuts, and 1 copper stud-with the transformer tank (ø36.5-R3) excluded from the supply scope; its body and eyebolt are made of brass-tin plated material, and its core technical specifications include a rated voltage of 1.2 KV, rated current of 250 A, creepage distance of no less than 25 mm, lighting impulse withstand voltage of 30 KV, and dry power-frequency withstand voltage of 8 KV, along with key dimensions such as t=6.35±0.2, 4-R10, 44.5+0.5, 50.8, 035.31, 047.75, a tank hole size of ø36.5, and adaptation to the 12″-13 specification.

03 Testing

For the pole mounted transformer’s LV bushing, the dry power-frequency withstand voltage test is performed to validate its insulation performance under rated operating scenarios-inline with the ANSI-1.2KV/250A standard, the bushing (featuring a creepage distance of no less than 25 mm) is exposed to an 8 KV power-frequency voltage in a dry environment for a specified period, requiring no breakdown, flashover, or abnormal leakage current to occur, thereby ensuring the bushing can reliably resist electrical stress and avoid insulation failures during practical application.

04 Packing and Shipping

05 Site And Summary

At SCOTECH, our pole mounted transformers are engineered to meet the stringent demands of outdoor power distribution. Built with rugged, weather-resistant construction, efficient energy conversion, and long-term reliability, they deliver stable power to residential, commercial, and rural grids-even in harsh environmental conditions. Backed by our decades of expertise in transformer manufacturing, every unit is rigorously tested, supported by comprehensive technical services and after-sales care. Whether you require standard configurations or customized solutions, we are committed to powering your projects with precision and performance. Contact our team today to explore how our pole mounted transformers can optimize your power distribution network.