25 kVA-333 kVA Single Phase Pole Mounted Transformer

DINGXIN manufactures a complete range of single-phase pole-mounted transformers for overhead distribution networks. These transformers step medium-voltage electricity down to the utilization voltage required by residential, commercial, agricultural and light-industrial consumers.

Installed directly on a utility pole, the transformer requires no separate transformer room or ground-level foundation. Its compact construction helps reduce land use, civil work and installation costs, making it particularly suitable for urban and rural overhead distribution systems.

DINGXIN pole-mounted transformers are available in three principal configurations:

• Conventional type: supplied with basic transformer protection interfaces for coordination with externally mounted protective devices;
• Completely Self-Protected type—CSP: equipped with integrated protective components such as a primary fuse, surge arrester and secondary circuit breaker, subject to the approved design;
• Interrupter-protected type: configured with an internal primary protective device to meet the customer’s distribution-protection requirements.

Standard product capacities range from 10 kVA to 250 kVA. Other ratings, including units up to 333 kVA, may be developed following a technical review of pole strength, transformer weight, voltage, accessories and installation requirements.

The primary voltage, secondary voltage, winding material, core material, insulating liquid, protection system and mounting arrangement can all be customized.

Dingxin manufactures a complete line of single-phase pole transformers product line. Single-phase transformers are available as conventional (5-167kVA), completely self-protected (CSP 5-75kVA), or interrupter-protected (5-167kVA) in a variety of ratings to meet or exceed the requirements of applicable ANSI® and NEMA® standards. Units designed per Rural Utilities Service (RUS) standards are also available.

CSP transformers have direct connected primary arresters, secondary circuit breakers, and internal primary voltage fuses. This eliminates the need for separately mounted protective devices and provides reduced installation costs.

Compact Pole-Mounted Design

The transformer is installed directly on a utility pole and does not occupy additional ground space. No separate substation room or transformer foundation is normally required, helping reduce civil construction and installation costs.

Energy-Efficient Performance

The magnetic core and windings are designed to control no-load and load losses. Options include a conventional CRGO silicon-steel core or an amorphous-alloy core for applications requiring particularly low no-load losses.

Energy-efficiency levels can be designed according to the applicable project specification. Compliance with U.S. Department of Energy requirements must be confirmed for the specific model, rating and market.

Outdoor Weather Protection

The sealed tank helps protect the transformer’s internal insulation from rain, dust and external contamination. The coating system can be selected according to the installation environment, including standard inland or enhanced coastal corrosion protection.

Flexible Voltage and Capacity Options

DINGXIN supports a wide range of primary and secondary voltages, capacities, frequencies, taps and bushing arrangements. Custom dual-voltage and special-ratio transformers are also available after engineering review.

Optional Integrated Protection

For CSP configurations, protective components can be installed directly on or inside the transformer. This can reduce the need for separately mounted devices, simplify field wiring and lower installation costs.

Low Maintenance Requirements

The sealed construction, corrosion-resistant coating and durable outdoor components help reduce routine maintenance requirements and support long-term outdoor service.

Fast Installation and Deployment

Pole-mounted transformers can be installed, replaced or relocated more quickly than many ground-mounted distribution systems. This makes them suitable for temporary supply, seasonal loads and rapidly expanding distribution networks.

Typical Capacity Range

Small Distribution Loads: 10–50 kVA

Common ratings include:

• 10 kVA;
• 15 kVA;
• 25 kVA;
• 37.5 kVA;
• 50 kVA.

These ratings are commonly used for individual houses, small farms, local shops, rural consumers and small groups of residential loads.

The 25 kVA, 37.5 kVA and 50 kVA ratings are among the most frequently selected capacities for residential and light-commercial distribution.

Medium Distribution Loads: 75–100 kVA

Typical applications include:

• schools;
• churches;
• small shopping centers;
• workshops;
• groups of residential customers;
• small factories;
• agricultural processing facilities.

Large Pole-Mounted Loads: 167–250 kVA

Larger ratings can serve:

• commercial buildings;
• light-industrial loads;
• larger customer groups;
• agricultural processing plants;
• utility distribution reinforcement;
• special grounding or infrastructure applications.

Ratings above 167 kVA require careful confirmation of pole loading, lifting, mounting brackets, clearances and local utility requirements.

PACKING:

Conventional Pole-Mounted Transformer

The conventional configuration provides the transformer’s core voltage-conversion function while external protection is coordinated separately by the utility or project designer.

Typical external devices may include:

• cutout fuse;
• surge arrester;
• secondary protection;
• disconnecting equipment.

Conventional transformers provide a simple and flexible solution where the utility already has a standardized external-protection arrangement.

Completely Self-Protected Transformer—CSP

The CSP configuration integrates several protective components with the transformer.

Depending on the approved design, a CSP transformer may include:

• direct-connected primary surge arrester;
• internal primary fuse;
• secondary circuit breaker;
• overload warning or indication;
• emergency overload function;
• de-energized tap changer.

Integrating these devices can:

• reduce separately mounted components;
• simplify field installation;
• reduce wiring and hardware;
• coordinate transformer protection;
• lower total installation costs.

CSP configurations are commonly available from 5 kVA to 75 kVA, with larger ratings subject to design review.

Interrupter-Protected Transformer

An interrupter-protected transformer uses an internal primary interrupting or protective device while retaining a different secondary-protection arrangement from a complete CSP unit.

The final protection system should be selected according to:

• available fault current;
• primary fuse coordination;
• secondary conductor rating;
• transformer inrush current;
• overload requirements;
• utility protection practices.

Standard and Optional Features

Tank and Mechanical Construction

• Sealed outdoor transformer tank;
• corrosion-resistant tank and cover coating;
• coating system available for applicable IEEE enclosure-integrity requirements;
• heavy-duty lifting lugs;
• pole hanger brackets;
• recessed tank bottom to reduce damage while moving the unit;
• tank grounding provisions;
• visible cover-ground connection when required;
• corrosion-resistant cover band;
• laser-engraved or stainless-steel nameplate;
• internal liquid-level mark;
• automatic pressure-relief device.

IEEE C57.12.31 specifies enclosure and coating-integrity requirements for carbon-steel pole-mounted equipment in non-coastal environments. Coastal or highly corrosive sites may require a different or enhanced coating specification. IEEE C57.12.31-2020

Bushings and Terminals

• Wet-process porcelain high-voltage bushings;
• high-voltage bushings selected for the project insulation class;
• polymer low-voltage bushings where applicable;
• tin-plated high- and low-voltage terminals;
• terminals suitable for copper or aluminum conductors, when specified;
• permanently identified secondary leads;
• arrester mounting and grounding provisions;
• cover-mounted or side-wall bushing arrangements.

Core and Windings

• CRGO silicon-steel core;
• optional amorphous-alloy core;
• copper or aluminum windings;
• interlaced core-type construction where required by the approved design;
• optimized flux density;
• controlled no-load and load losses;
• mechanically supported windings designed for the specified short-circuit duty.

Insulating Liquid

Available liquid options include:

• electrical-grade mineral insulating oil;
• natural ester insulating fluid, including specified approved brands.

Natural ester fluid may offer a higher fire point and improved environmental characteristics, but the final liquid selection must consider temperature, materials compatibility, maintenance, fire-safety requirements and local regulations.

Protection and Monitoring Accessories

Available options include:

• primary surge arrester;
• internal primary fuse;
• secondary circuit breaker;
• CSP protection package;
• current-limiting fuse;
• automatic pressure-relief device;
• de-energized tap changer;
• liquid-level indicator;
• temperature indicator;
• pressure-vacuum gauge;
• drain and sampling valve;
• wildlife protection;
• Internal Fault Detector—IFD, where technically applicable;
• customer-specified monitoring devices.

The following values are typical reference data for copper-wound, silicon-steel-core configurations. They are not guaranteed final dimensions.

Dimensions and weights vary with voltage class, insulation level, winding material, core material, insulating liquid, bushings, protection devices and mounting arrangement. Always use the approved outline drawing for foundation-free pole design, lifting and installation.

• Residential communities;
• Rural electrification;
• Farms and irrigation systems;
• Retail stores and commercial buildings;
• Schools and public facilities;
• Workshops and small factories;
• Street lighting;
• Railway and bridge auxiliary power;
• Temporary and emergency power distribution.

Customization Information

For a fast quotation, please provide:

1. Required capacity;
2. Primary and secondary voltage;
3. Frequency;
4. Conventional, CSP or protected configuration;
5. Copper or aluminum winding;
6. Mineral oil or natural ester fluid;
7. Applicable standard;
8. Installation location and environment;
9. Required quantity and delivery destination.

Get the Right Transformer for Your Project

DINGXIN manufactures customized transformers and substations for utility, commercial, agricultural and industrial projects.

Send us your capacity, voltage and installation requirements to receive a customized single-phase pole-mounted transformer proposal.