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The 50 kVA single phase pole mounted transformer is built for overhead distribution lines, where the unit is bolted to the pole cross-arm and feeds the service drop directly. It serves residential streets, small commercial premises, agricultural holdings and rural pumping points where a ground level installation is impractical. The primary is stepped down from 2.4 kV to 34.5 kV, with off-circuit taps of plus or minus 2 x 2.5 percent for voltage adjustment on site.
Construction of the 50 kVA single phase pole mounted transformer follows the CSP or conventional arrangement, with grain-oriented core steel and aluminium or copper windings, cooled by ONAN oil circulation through external radiators. Insulation is mineral oil or FR3 natural ester, the tank is mild steel or stainless steel, and every unit is routine tested to IEEE, ANSI, IEC and CSA practice before shipment.
Rated Capacity | 50 kVA |
Type | CSP Type / Conventional Type |
Rated Primary Voltage | 2.4-34.5 kV or Customized |
Secondary Voltage | Customized |
Frequency | 50/60 Hz |
Vector Group | Ii0, Ii6 |
HV Tap Changer | ± 2×2.5% HV taps |
BIL | 30-150kV |
Efficiency | DOE 2016/CSA/IEEE/GB |
Impedance Voltage | 1.1-5.75% |
Cooling Method | ONAN/ KNAN |
Operation | Step Down |
Standards/Certificate | IEEE, ANSI, IEC, CSA, NEMA, ISO, CE |
Application | Residential/commercial/small industry/power distribution systems |
Altitude | ≤1,000 m, 1000–2000 m, 2000–3000 m, >3000 m |
Transformer Oil | Mineral Oil or FR3 |
Winding Material | Aluminum/Copper |
Core Material | Grain-Oriented Electrical Steel |
Color | Customized |
Tank Material | Mild Steel / Stainless Steel |
The core is stacked from grain-oriented electrical steel and clamped into a closed magnetic circuit. Mitered joints and a single-point core ground hold no-load loss and sound level down, which matters on a pole where the unit runs unattended for years.
The low-voltage winding carries the service current, so it is wound as aluminium or copper foil or strip. A uniform distribution of ampere-turns keeps stray loss and hot spots low and gives the winding a high short-circuit withstand capability.
The high-voltage winding is built as a multilayer cylinder with oil ducts between layers, insulated for primary voltages from 2.4 kV to 34.5 kV and for a basic impulse level of 30 kV to 150 kV.
The tank is filled with mineral oil or a natural ester such as FR3. Besides insulating the windings, the fluid carries heat from the active part to the tank walls and keeps moisture away from the paper insulation.
A mild steel or stainless steel tank with external radiators dissipates the heat by natural oil circulation and ambient air, the ONAN cooling that is standard for this family. A KNAN arrangement is available where the load profile requires it.
Primary connections are brought out through porcelain or polymer bushings sized for the system voltage. Cable or arrester connections are made on the primary side without opening the tank, so the sealed oil space is never exposed in service.
The tank is fitted with a mounting bracket and lifting provisions so the transformer can be hoisted and bolted directly to a pole cross-arm. No pad, vault or fenced compound is needed, which is what makes this family the standard choice for overhead distribution.
Two arrangements are built: a completely self-protected (CSP) unit with internal primary protection, or a conventional unit that relies on external cutouts and arresters. The choice follows the utility practice of the network the transformer is going into.
Off-circuit taps give plus or minus 2 x 2.5 percent above and below the rated voltage, so the secondary voltage can be trimmed on site to the actual primary level. Taps are changed with the unit de-energised.
The secondary leads are brought out to clearly marked terminals for the service connection. A stainless nameplate records the rated capacity, voltages, vector group Ii0 or Ii6, impedance and the standard the unit was tested to.
Every pole mounted transformer is tested before shipment against the applicable standards and the customer specification — from incoming raw material to the final routine test on the factory floor.
Quality starts with what comes through the gate. Tank steel, core laminations, winding conductor and insulating oil are checked against the approved specification for each batch, and supplier records are kept so that every component can be traced back to its heat number.
Progress checks are carried out at the winding, core stacking, tanking and oil-filling stages, so that every 50kVA single-phase pole mounted transformer is verified against its design before it reaches final assembly.
Each unit then goes through routine testing in accordance with IEEE / ANSI, IEC and CSA practice — insulation resistance, winding resistance, voltage ratio and polarity, no-load loss and current, load loss and impedance, applied and induced voltage withstand, and oil tightness and pressure testing. Efficiency is verified to DOE 2016 levels.
The finished transformer leaves the factory with a routine test report and a certificate of conformity, recording the measured values against the rated data on the nameplate.
50kVA Single Phase Pole Mounted Transformers are configured to the distribution practice of the project. Primary voltage, secondary voltage and vector group are selected first, then the protection and material options are added on top.
Primary windings can be built from 2.4 kV up to 34.5 kV, or to a customized primary voltage where the network requires it, and the secondary winding is wound to the project requirement. Vector group Ii0 or Ii6 is available, and the unit can be supplied for 50 Hz or 60 Hz operation.
The active part can be wound in aluminium or copper, on a core of grain-oriented electrical steel, and the tank can be supplied in mild steel or stainless steel with a customized finish. Insulation fluid is chosen as conventional mineral oil or as a natural ester such as FR3 where fire risk or environmental sensitivity calls for it.
Protection and mounting options cover the CSP or conventional arrangement, HV taps at plus or minus 2 x 2.5 percent, and the bracket and terminal layout needed for the pole hardware already in service on the line.
Every single-phase pole mounted transformer is packed, documented and shipped ready for pole installation.
Secure Packaging: Weather-resistant crating protects the tank, bushings and radiators against moisture, vibration and impact during transport and storage.
Oil-Tight Preparation: Units are shipped with the oil level and sealing checked after the routine tests, and the tank is sealed for the journey.
Reliable Transport: Road, rail or sea freight is arranged according to the project schedule and destination.
Complete Documentation: Routine test report, certificate of conformity, nameplate data, installation instructions and shipping documents travel with the unit.
Installation Support: Guidance on pole mounting, primary and secondary connections, earthing and energisation is available for smooth commissioning.
The single phase pole mounted transformer range covers 5 kVA to 167 kVA, which stays within the standard loading of a pole cross-arm while serving anything from a single residence to a small commercial or light industrial service.
Units are built to order, so other ratings and primary voltages within the range can be quoted for a specific project.
The basic impulse level is matched to the primary voltage class of the unit, and lies between 30 kV and 150 kV across the range.
Every unit goes through routine testing, and the results are recorded in a factory test report issued with the transformer.
