2025-08-12
A pole-mounted transformer is an electrical transformer mounted on an overhead utility pole, commonly used in power distribution networks to step down high primary voltages (typically 2.4 kV to 34.5 kV) to lower secondary voltages (120/240V or 347/600V) for safe delivery to homes and businesses.
1. Voltage Transformation
Converts high-voltage electricity from distribution lines to safer, usable voltages (e.g., 7.2 kV → 120/240V for residential use).
2. Physical Structure
Tank: Filled with dielectric oil for insulation/cooling.
Bushings: Insulated terminals connecting to overhead lines (primary) and output cables (secondary).
Core/Coils: Internal electromagnetic components that enable voltage reduction.
3. Mounting Hardware
Bolted directly to the pole using robust brackets, typically 10–40 feet above ground.
4. Protective Devices
Lightning Arresters: Divert surges from storms.
Fused Cutout: Disconnects the transformer during faults (visible as a hinged fuse holder).
Pressure Relief Valve: Prevents tank rupture during internal faults.
5. Cooling
Oil dissipates heat; some models have fins or radiators for enhanced cooling.
Space Efficiency: Ideal for areas lacking ground space (suburbs, rural routes).
Cost-Effective: Cheaper installation/maintenance vs. ground units.
Safety: Elevated position reduces tampering/flood risks.
Accessibility: Easier for utility crews to service via bucket trucks.
Residential neighborhoods
Rural electrification
Commercial strips (small businesses)
Temporary power for construction sites
Capacity: Typically 5 kVA to 500 kVA (larger needs require ground substations).
Vulnerability: Exposed to weather, wildlife, and vehicle accidents.
Aesthetics: Some communities prefer underground lines for visual appeal.
