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A pole-mounted transformer for solar & rural grids hangs from the crossarm of a distribution pole and serves a small group of customers directly from the overhead line. It is used on rural electrification schemes, farm service drops, village mini-grids and solar-plus-storage feeders where a ground-mounted unit would need a fenced compound. Single-phase designs dominate, with three-phase versions available where the load mixes lighting, irrigation pumps and small workshops.
The pole-mounted transformer for solar & rural grids is a fully sealed oil-immersed unit with a corrugated tank and no conservator, cooled by ONAN, with a pressure-relief valve and an oil-level gauge for inspection from the ground. A drop-out fuse and a zinc-oxide arrester protect the high voltage side, CRGO silicon steel and copper windings keep losses low, and porcelain or composite bushings take the overhead connection. Wound-core and amorphous cores are available as lower-loss options.
| Electrical & Standards | Rated capacity | 500 kVA and below per unit; typical series 10-500 kVA |
Voltage combination (HV-LV) | Primary 12470Y/7200 V, 24940Y/14400 V etc. (HV <= 34.5 kV); secondary 240/120 V single-phase three-wire, or three-phase | |
Phases | Single-phase mainstream for residential / farm service; three-phase designs available | |
Tapping | Off-circuit +/-2x2.5%, taps on HV side | |
Rated frequency | 60 Hz for North America; 50/60 Hz per destination grid | |
Cooling | ONAN, fully sealed oil-immersed construction | |
Protection / IP & environment | Outdoor weatherproof fully sealed tank; drop-out fuse and zinc-oxide arrester on HV side; -25 to +55 degC | |
Standards & certification | GB、CE、IECEE CB、KEMA、ISO; IEEE C57.12.20 + DOE 10 CFR 431 for North America | |
| Structure & Materials | Enclosure & shell | Fully sealed corrugated tank (no conservator) or conservator type; pressure-relief valve and oil-level gauge |
Core | CRGO silicon steel; wound-core and amorphous-metal options for lower no-load loss | |
Windings | Electrolytic copper wire-wound mainstream; aluminum for low-cost options | |
Insulation system | Oil-paper insulation inside the sealed tank | |
Insulating oil | Mineral oil standard; natural ester (high fire point) and low-pour-point oils optional | |
Transformer tank | Fully sealed or conservator type | |
Bushings & terminations | Porcelain or composite silicone rubber; ANSI cover-mounted arrangement for export | |
Corrosion / coating | Outdoor weathering polyurethane topcoat; C4/C5 anti-corrosion for coastal sites | |
Mounting & base | Single- or double-pole rack; hung from crossarm via lifting lugs / ear plates; bottom clearance >= 2.5 m |
The core is built from CRGO Hi-B silicon steel with fully mitered joints, which keeps no-load loss and sound level down over the long operating hours of a generation asset. An amorphous metal core is available on request where no-load loss is the deciding factor.
On the inverter side the winding carries a high current at a low voltage, so the low voltage winding is produced as electrolytic copper foil. Foil construction gives a uniform current distribution, a low stray loss and a good withstand against the harmonic currents that inverter duty imposes.
The high voltage winding is wound from electrolytic copper wire and insulated for a system voltage of 10 kV or 35 kV, with an aluminium winding offered as an option where the project specifies it.
Oil-immersed units use an oil-paper composite insulation system with PCB-free mineral oil, and ester oil where the project is environmentally sensitive. Where oil is not acceptable, the transformer is supplied as a dry-type unit with epoxy cast-resin insulation.
The tank is fabricated from Q235 corrugated or plain plate and is fully sealed, with no conservator. Cooling is by oil circulation to the tank walls and radiators for oil-immersed units, or by air for dry-type units, with forced cooling applied where the rating requires it.
The enclosure is a double-layer sandwich construction in steel or composite board with a fireproof thermal-insulation filling and a rain-shed roof. Natural ventilation is combined with forced ventilation so that heat is rejected from the transformer room under full load.
The high voltage and low voltage rooms are fully separated, and the transformer is mounted externally or semi-externally so that its heat does not load the switchgear rooms. Door interlocks prevent access to a live compartment in service.
Porcelain or composite bushings are fitted for the high voltage connections, and the cables enter from below through a bottom entry with cable seals, which suits the buried cable practice used on most PV and wind sites.
Vector group Dyn11 is the common connection, with Ynd11 applied where the grid and earthing arrangement calls for it; the delta low voltage winding suppresses third harmonic currents. Off-circuit taps of plus or minus 2 x 2.5 percent are standard, and an on-load tap changer can be specified where the grid voltage moves during the day.
Base lifting lugs allow the complete unit to be lifted in one piece onto its foundation, and the footprint follows the factory datasheet. For coastal or offshore sites a C4 or C5 anti-corrosion coating system, silicone seals, anti-condensation heating and rodent-proof mesh are applied.
Every renewable energy transformer is routine tested as a transformer and, where the scope includes the enclosure and switchgear, function tested as a complete assembly before shipment.
Core steel, foil and wire conductor, tank plate and insulating oil are inspected against the approved specification on receipt, and traceability records are kept for every batch used in the active part.
Winding, core stacking, tanking and oil filling are checked stage by stage, so that every Pole-Mounted Transformer for Solar & Rural Grids is verified against its design before it moves to final testing.
Routine testing follows IEC 60076 and covers winding resistance, ratio and vector group, no-load and load loss, impedance, insulation resistance, applied and induced voltage withstand, and oil tightness on sealed units. Where the supply includes the enclosure, the assembly is checked to IEC 62271-202 practice and against the applicable PV or wind grid-code requirements.
The unit is shipped with a routine test report and a certificate of conformity, recording the measured values against the nameplate data.
Pole-Mounted Transformer for Solar & Rural Grids is configured around the generation asset it serves: the inverter or turbine output voltage, the collection network voltage and the grid connection requirements come first, and the transformer, enclosure and protection follow from them.
Capacity is built from 1000 kVA to 3150 kVA and above, with higher ratings engineered for larger blocks. The high voltage side is normally 10 kV or 35 kV, and the low voltage side follows the inverter, typically 0.27 kV, 0.315 kV, 0.4 kV or 0.8 kV, with 0.8 kV used for large central inverters.
Cooling is oil-immersed ONAN or ONAF, or dry-type AN or AF where no oil is permitted. Insulation is oil-paper composite with mineral oil, or ester oil for environmentally sensitive projects; vector group Dyn11 or Ynd11, off-circuit taps or an on-load tap changer, CRGO Hi-B or amorphous core, and aluminium windings are all selectable.
For the enclosure and site conditions, the double-layer shell, compartment layout and C4 or C5 anti-corrosion coating are matched to the location, with silicone seals, anti-condensation heating and rodent-proof mesh for humid, coastal or desert sites.
Renewable energy transformers are packed for long-distance transport to generation sites, which are often remote and have limited handling equipment on arrival.
Secure Packaging: Bushings, accessories and control cabinets are protected and braced against vibration and impact, and openings are sealed against moisture and dust.
One-piece Lifting: Base lifting lugs allow the complete assembly to be lifted in one piece, so no reassembly is needed at the site.
Reliable Transport: Road, rail or sea freight is arranged to the project schedule, with the route and handling method agreed for oversized units.
Complete Documentation: Routine test report, certificate of conformity, drawings, manuals and shipping documents travel with the unit.
Installation Support: Guidance on foundation, cable entry, earthing, protection settings and energisation is available through commissioning.
Cooling follows the transformer type selected for the site. Oil-immersed units use ONAN natural circulation, with ONAF fans added where the rating requires it, and dry-type units use AN natural or AF forced air cooling.
The active part is selected against the loss and harmonic duty of the plant.
The vector group is chosen for the grid and earthing arrangement of the project, and for step-up duty it follows the low voltage winding configuration of the inverter, turbine or converter that feeds the unit. The connection applied to this unit is stated in the specification table.
