225 KVA Small Pad Mounted Transformer-13.8/0.44 KV | Guyana 2025

Weatherproof, heatproof, and tough – Pad Mounted Transformer protects your power around the clock.

01 General

1.1 Project Description

The 225kVA three-phase pad-mounted transformer is a compact, self-contained power distribution unit designed for outdoor ground-level installation. Fully enclosed within a durable mild steel tank, this transformer is engineered for safety, reliability, and long-term performance in demanding environments. With a low-profile, tamper-resistant design, it is the preferred choice for underground distribution networks serving residential, commercial, and industrial loads.

Compliance with International Standards

Manufactured in strict accordance with IEEE Std C57.12.34-2022, this transformer meets rigorous electrical, dimensional, mechanical, and safety requirements for three-phase, 60Hz, liquid-immersed, self-cooled, compartmental-type distribution transformers. Its copper windings and three-legged core construction ensure optimal efficiency and longevity, while the mineral oil-immersed design provides excellent insulation and natural cooling.

Electrical Performance

Rated at 225kVA with a primary voltage of 13.8kV Delta and secondary voltage of 440Y/254V, this unit features a Dyn11 vector group, ensuring balanced and reliable three-phase power delivery. The impedance is set at 3.5%, with an ONAN (Oil Natural Air Natural) cooling method that guarantees stable temperature control under continuous load. Temperature rise limits are maintained at ≤65°C for the average winding and top oil level, with a hot-spot rise not exceeding 80°C. The transformer achieves an impressive efficiency of 98.94%, minimizing energy losses and reducing operational costs. With a frequency of 60Hz, it is specifically designed for power distribution systems in regions operating at this standard.

1.2 Technical Specification

225kVA small pad mounted transformer specifications type and data sheet

1.3 Drawings

225 kVA small pad mounted transformer diagram drawing and size.

02 Manufacturing

2.1 Core

The small pad mounted transformer adopts a three‑leg core structure, fully matching the 225 kVA rated power, 60 Hz frequency, and 3.5% impedance design, and complies with IEEE Std C57.12.34‑2022 requirements for flux density and loss control. For reliability, the core has passed no‑load loss and exciting current tests; measured no‑load loss is below the design limit, with stable exciting current and good magnetic circuit symmetry. Quality is ensured by using high‑permeability grain‑oriented silicon steel, stepped lap technology, and fully automatic stacking with laser positioning, plus single‑point grounding to prevent circulating currents. Manufacturing highlights: high‑permeability material, stepped lap joint, automatic stacking, and precise grounding.

2.2 Winding

Windings are made of copper, with primary 13.8 kV and secondary 440Y/254 V, matching the ±2×2.5% de‑energized tap changer, and conform to IEEE C57.12.34‑2022 insulation structure and temperature rise limits. The windings have passed induced voltage test, applied voltage test, ratio test, and load loss test; measured load loss is below design value, average winding temperature rise ≤65°C, and hot‑spot rise ≤80°C. Quality is ensured by constant‑tension winding, high‑temperature insulation materials, and vacuum drying. Manufacturing highlights: continuous / helical winding, reinforced end insulation, and low‑voltage foil winding for higher short‑circuit strength and heat dissipation.

2.3 Tank

The tank is of sealed type with a bolted cover, oil weight 450 L, total weight 1535 kg, suitable for outdoor installation, and meets IEEE C57.12.34‑2022 requirements for strength, corrosion protection, and sealing. Reliability tests include tank leak detection and optional negative pressure withstand test – no leakage, sound structure. Quality is assured by using mild steel, controlled welding process, 100% visual inspection plus kerosene leak test, and final painting with high‑gloss Munsell 7GY 3.29/1.5 green coating. Manufacturing highlights: modular compartment design, separate HV/LV sections, lifting lugs, grounding pads, and a tamper‑proof control cabinet.

2.4 Final Assembly

The assembly integrates 6 separable insulated HV connectors, 4‑hole spade‑type LV terminals, neutral grounding pad, 4‑position load break switch, 3 current‑limiting fuses, and 3 bayonet fuses – fully matching the drawing parameters. The assembly process and grounding system comply with IEEE C57.12.34‑2022. The complete unit has passed ratio, polarity, angular displacement, no‑load loss, load loss, dielectric withstand, and continuity tests. Quality is ensured by standard operating procedures, torque verification, and double‑locked electrical connections. Manufacturing highlights: separate HV/LV compartments for safe operation, 4‑position load break switch, and integrated fuse protection.

2.5 Terminal And Grounding Provisions

The high-voltage compartment is equipped with six separable insulated connectors rated at 200A, supporting safe dead-front operation. The low-voltage side includes three resin-cast bushings with spade-type terminals (four-hole configuration), rated at a BIL of 30kV and a 60Hz dry one-minute withstand voltage of 10kV. One low-voltage neutral bushing (XO) is provided with a strap to the grounding pad, along with two grounding terminals (steel pads with single-hole connections), one located in the HV compartment and the other in the LV compartment, ensuring comprehensive grounding for operational safety.

03 Testing

All electrical and mechanical parameters are covered by tests (ratio, losses, impedance, dielectric, temperature rise, etc.), strictly following IEEE C57.12.34‑2022 routine test requirements. Most important test results: ratio error <0.5% at all tap positions; no‑load loss below design value, efficiency 98.94%; load loss and impedance match 3.5%; applied voltage withstand: 34 kV/60 Hz on HV side and 10 kV/60 Hz on LV side – passed; induced voltage test – passed; tank leak test – no leakage; continuity test – passed. All test equipment is regularly calibrated, data automatically recorded, and a complete test report is provided. Manufacturing highlights: test procedure aligned with IEEE standards, with optional type tests (temperature rise, impulse, short‑circuit, etc.) available upon request.

04 Packing and Shipping

4.1 Packing

Packing is suitable for road or sea transport, providing protection against moisture, shock, and rust, complying with IEEE and export shipping standards. Reliability is confirmed by no unit displacement after packing, intact protective film, and optional vibration simulation test passed. Before packing, a final visual inspection and accessory check are performed, followed by eco‑friendly wooden case or steel frame packing. Manufacturing highlights: separate protection for HV/LV bushings, and anti‑impact treatment for external parts such as the oil valve, nameplate, and grounding pads.

4.2 Shipping

Shipping is compatible with container or break‑bulk vessels; dimensions 1480×1220×1610 mm, weight 1535 kg, meeting IEC/ISO logistics standards and import country requirements. Before shipping, center of gravity is marked and lashing is verified to avoid tilting or collision risks. We cooperate with professional logistics partners, providing transport insurance and real‑time tracking. Manufacturing highlights: optional transport simulation test ensures no performance degradation after long‑distance shipment.

05 Site And Summary

In summary, this small pad mounted transformer delivers a reliable combination of performance, durability, and low life‑cycle cost. It is a complete solution designed to meet the rigorous demands of today’s utility applications. Choose this product as your trusted partner for building a smarter, more reliable electrical infrastructure.