IEC60076 Step Up Medium Power Transformer 1250kVA 0.415kV to 11kV for Wind &

The 1250kVA step-up medium power transformer is a three-phase, IEC 60076 compliant unit designed to connect renewable energy generator sets to the medium voltage grid. With a primary low-voltage rating of 0.415kV and a secondary high-voltage side of 11kV, it converts power from wind turbine generators and solar PV inverter outputs into transmission-ready levels. Configured as a hermetically sealed oil-immersed transformer or an optional dry-type version, it targets wind farms, solar parks, and hybrid renewable energy plants that demand uninterrupted performance in outdoor, high-harmonic operating environments.

• Harmonic-Hardened Core and Winding Assembly – Special electrostatic shielding and reinforced insulation withstand the harmonic currents and voltage distortions commonly produced by wind converters and solar inverters, preserving winding life.
• High Energy Efficiency Under Cyclic Loading – Low no-load and load losses keep energy yield high even when generation varies across the day, directly supporting project ROI and grid code compliance.
• Rugged Outdoor-Ready Construction – A weatherproof, sealed-tank design with anti-condensation heaters, corrosion-resistant coatings, and an IP54-rated terminal box ensures reliable operation under humidity, dust, salt spray, and wide temperature swings.
• Flexible Tapping and Vector Group Configurations – Standard Dyn11 vector grouping with ±2×2.5% off-circuit taps on the 11kV side allows precise voltage adaptation to site-level collector network conditions.
• Full IEC 60076 Compliance and Type-Test Portfolios – The transformer is fully type- and routine-tested according to IEC 60076, which simplifies approval procedures with EPC contractors, grid operators, and project lenders.

Wind and solar power generator sets introduce a specific combination of electrical and site-related difficulties that off-the-shelf distribution transformers are not built to handle. Inverter-fed sources create persistent high-frequency harmonic content and voltage waveform distortions that accelerate winding hot-spot ageing. At the same time, the transformer is typically installed outdoors, exposed to thermal cycling from morning startups, midday peaks, and overnight shutdowns, while operating at partial loads for extended periods. Reliability demands are high because any unplanned outage directly stops energy export from multiple inverters or turbines.

Our response in this 1250kVA step-up transformer focuses on those real operational demands:

• Harmonic and Common-Mode Noise Suppression: We integrated an earthed electrostatic screen between the LV and HV windings and employed a foil-wound LV coil. This design suppresses converter-induced high-frequency interference and provides a controlled path for common-mode currents, preventing them from degrading insulation or leaking into the collector grid. The Dyn11 connection naturally traps zero-sequence components on the LV delta side, keeping the MV network cleaner.
• Resilience Under Variable Loading: Core and winding selection are targeted for low-loss performance both near full load and at the lighter average loads typical of solar parks and wind farms. The ONAN cooling philosophy eliminates fan-related auxiliary systems that could fail in dusty or snow-prone environments while still managing thermal stresses from daily load cycling.
• Outdoor Endurance without Extra Housing: A hermetically sealed oil tank prevents contact between the insulation liquid and ambient air, avoiding moisture ingress and oxidation. Paired with a C5-M suitable coating system and protected gauges, the unit can be placed adjacent to inverter stations or turbine towers without the need for a dedicated shelter — reducing civil works and installation costs.
• Grid Integration Readiness: The 11kV high-voltage side with off-circuit taps permits fine adjustment once the actual collector bus voltage is confirmed during commissioning, minimizing reactive power demand and helping the power plant meet its connection agreement limits. Combined with full IEC 60076 test documentation, this eases the interface review process with transmission system operators and EPC technical teams.

• Q1: What voltage ratio and vector group does this 1250kVA step-up transformer use for a typical wind or solar project?

  A: The standard configuration is 0.415kV (LV) to 11kV (HV) with a Dyn11 vector group. The LV delta winding gives a reliable path for harmonic circulation, while the HV wye neutral is brought out for system earthing. Other low-voltage windings, such as 0.4kV or 0.69kV, are available to match your generator set output.

• Q2: Can this unit endure the harmonics and voltage distortion produced by solar inverters and wind converters?

  A: Yes. An electrostatic screen between windings, combined with an LV foil-winding construction, significantly reduces the effects of inverter-induced harmonics and common-mode noise. The Dyn11 connection further isolates zero-sequence currents from the collector grid, helping the transformer maintain its thermal design margins over the project lifetime.

• Q3: Is this transformer fully compliant with IEC 60076, and what type-test evidence is provided for EPC and grid approval?

  A: The transformer is designed, manufactured, and tested under the IEC 60076 series. It comes with complete routine test certificates and type-test reports (including temperature-rise and lightning impulse) from an accredited test laboratory. This documentation directly supports EPC quality inspection plans and grid connection application packages.

• Q4: How does this step-up transformer perform in hot climates or high-altitude solar and wind farm locations?

  A: The standard design operates continuously from -25 °C to +50 °C ambient at 1000 m altitude. For higher altitudes or extreme heat, we adjust the cooling and insulation parameters — for example, by increasing oil volume, adjusting allowed temperature limits, or using natural ester fluid with a higher flash point — to maintain full 1250kVA rating without derating.

• Q5: What maintenance and monitoring equipment is included, and how is the transformer protected in remote installations?

  A: Every unit includes a pressure relief device, oil level indicator, winding temperature indicator with alarm/trip contacts, and a sampling valve. The hermetically sealed tank design removes the need for regular oil reconditioning. Optional accessories suchs as Buchholz relay, PT100 thermal probes, and online dissolved gas analysis (DGA) sensors can be integrated for unstaffed renewable energy sites where remote condition monitoring is critical.

• Q6: How is the transformer shipped and what support is available during on-site commissioning?

  A: The 1250kVA unit is delivered factory-filled with oil, fully assembled, and tested, ready for immediate lifting and connection on site. We provide comprehensive documentation, including lifting plans and installation instructions, and can arrange for commissioning supervision or full EPC support with our local service partners to assist during the first energization of the power plant.