Small on the pole, big on performance - Trust single phase pole mounted transformer for reliable single-phase distribution.
01 General
1.1 Project Description
167 kVA transformer electrical pole was delivered to Guyana in 2025. The rated power of the transformer is 167 kVA with ONAN cooling. The high voltage is 13.8 kV with ±2*2.5% tapping range (NLTC), the low voltage is 0.12/0.24 kV, they formed a vector group of Ii0.
The 167 kVA, single-phase pole-mounted transformer represents a highly reliable and efficient solution for overhead distribution networks, engineered to step down a high primary voltage of 13.8 kV to a low-voltage split-phase output of 120/240 V. Designed and manufactured in full compliance with ANSI/IEEE C57.12.20 and related IEEE C57 series standards, this transformer serves as a critical component for power distribution in residential neighborhoods, rural electrification projects, light commercial facilities, and agricultural applications, providing stable and high-quality power supply with minimal operational losses.
The transformer electrical pole features a robust oil-immersed, self-cooled construction with ONAN (Oil Natural Air Natural) cooling, enabling continuous rated operation under demanding outdoor pole-mounted conditions. Its sealed mild steel tank is equipped with weather-resistant coating, high-voltage porcelain bushings, low-voltage bushings, off-load tap changer, pressure relief device, and tank-mounted grounding provisions, ensuring long-term durability and safe handling in overhead environments. The transformer supports Ii0 vector group configuration and is wired with subtractive polarity, which aligns with IEEE C57.12.70 terminal marking standards for single-phase units and facilitates straightforward parallel operation and interconnection with standard utility grids.
Its combination of rugged pole-mounted design, advanced low-loss core technology, established subtractive polarity, plus superior insulation and short-circuit withstand capabilities, makes it an industry-preferred solution for decentralized last-mile power delivery in both urban fringe and remote area settings.
1.2 Technical Specification
167 kVA transformer electrical pole specifications type and data sheet
| Delivered to | Guyana |
| Year | 2025 |
| Type | Pole mounted transformer |
| Standard | IEEE & ANSI C57.12.00 |
| Rated Power | 167 kVA |
| Frequency | 60HZ |
| Phase | 1 |
| Polarity | Subtractive |
| Cooling Type | ONAN |
| Primary Voltage | 13.8 kV |
| Secondary Voltage | 0.12/0.24 kV |
| Winding Material | Copper |
| Angular displacement | Ii0 |
| Impedance | 2% |
| Tap Changer | ±2*2.5%(total range=10%) |
| No Load Loss | 0.379 kW |
| On Load Loss | 1.36 kW |
| Total loss | 1.739 kW |
| Basic lighting impulse (HV) | 95kV |
| Basic lighting impulse (LV) | 30kV |
1.3 Drawings
167 kVA transformer electrical pole diagram drawing and size.
02 Manufacturing
2.1 Core
| The core is made of high-grade, cold-rolled, grain-oriented silicon steel with a stepped lap joint design, effectively reducing hysteresis loss and eddy current loss. The entire core is annealed to minimize residual flux, resulting in significantly lower no-load current and no-load loss for improved operational efficiency. The clamping system ensures mechanical stability during transportation and long-term operation. |  |
2.2 Winding
 | Both HV and LV windings use high-purity oxygen-free copper conductors (aluminum optional) with compact winding geometry. Interlayer and interturn insulation employs high-temperature rated paper or Nomex® material, providing high short-circuit withstand capability. The design ensures uniform electric field distribution; partial discharge level is kept below 1/3 of the standard limit. Tapping range meets ±2×2.5% or custom requirements. |
2.3 Tank
| The tank is of fully sealed construction, welded from high-quality steel plates, and subjected to leak and pressure tests. The surface is treated with anti-corrosion outdoor paint (C5-M grade for aggressive environments), suitable for long-term exposure to sunlight, rain, snow, and salt spray. The cover is designed with rain shields, and bushing angles are optimized for pole mounting and cable connection. Radiator fins or corrugated walls are designed for optimized temperature rise with natural oil circulation (ONAN cooling). |  |
2.4 Final Assembly
 | The final assembly is carried out in strict accordance with IEEE standards, including core-winding stacking, vacuum oil injection, insulation treatment and accessory installation. The overall structure is compact, with reasonable layout of high-voltage and low-voltage bushings and tap changer, matching the overhead pole-mounted installation size and strength requirements. The polarity, vector group and winding coordination are calibrated to ensure stable and reliable field operation. |
03 Testing
All routine tests are completed in accordance with IEEE C57.12.90-2021, and all items are qualified:
- Winding resistance, voltage ratio and polarity test: qualified
- No-load loss & current: 0.366 kW, 0.47%, 3.294 A
- Load loss (85℃), short-circuit impedance & efficiency: 1.257 kW, 2.36%, 99.23%
- Applied voltage test: HV 34 kV/60 s, LV 10 kV/60 s, no voltage collapse
- Induced voltage withstand test: 150 Hz, 48 s, 2Ur, no voltage collapse
- Insulation resistance, sealing and oil dielectric test: all qualified
04 Packing and Shipping
4.1 Packing
- Primary packing: The transformer is sealed in an aluminum foil bag under vacuum, then packed in a wooden crate.
- Paint condition check: Before packing, the paintwork is inspected for any scratches or impacts; touch-up painting is applied as necessary.
- Documentation: Paper documentation (instruction manual, test report, etc.) is placed inside the crate.
- Spare paint: A small can of spare paint is included. Its location inside the crate is documented with a photo provided to the customer.
- Pallet/Base design: The wooden crate base is designed with 140 mm high skids (legs) to allow forklift entry from two opposite sides.
4.2 Shipping
Standardized logistics and transportation are adopted, suitable for land and sea transportation. The whole process is fixed and protected to avoid displacement and collision damage. The product is re-inspected before shipment to ensure that the transformer arrives intact and can be installed and put into use directly after arrival.
05 Site And Summary
Our single-phase pole-mounted transformer combines a compact design with easy installation and reliable performance. Built with high-quality silicon steel and a fully sealed structure, it delivers low no-load losses, high overload capacity, and long maintenance-free service life in harsh outdoor environments. Ideal for residential, agricultural, and small commercial loads, it offers a safe and cost-effective power solution. Choose our transformer for proven quality and dedicated support. Contact our sales team for specifications or ordering assistance.
