Inverter Duty Transformer for Solar Power Plant

✅ Application

  • Used in grid-connected solar PV plants
  • Converts inverter output (low voltage AC) to grid level voltage
  • Provides isolation + voltage step-up

👉 Solar panels → DC → inverter → AC (LV) → IDT → 11kV / 33kV grid

🔷 Technical Configuration

⚡ Voltage Levels

  • LT Side (Inverter side):
    • 400V / 415V / 690V (typical)
    • Multiple LT windings (1, 2, or 3 inputs)
  • HT Side (Grid side):
    • 11 kV / 33 kV

⚡ Winding Configuration

  • 1 LT winding → Single inverter connection
  • 2 LT windings → Dual inverter input
  • 3 LT windings (or more) → Multiple inverter inputs

➡ Multi-winding design reduces number of transformers in solar plant

⚡ Capacity Range

  • Typical: 100 kVA to 20 MVA
  • Can be customized based on plant MW size

⚡ Phase

  • 3 Phase Transformer (mandatory for solar utility plants)

⚡ Cooling

  • ONAN / ONAF (oil cooled)

🔷 Key Design Features (Solar Duty)

These transformers are NOT standard distribution transformers. They are specially designed for:

  • Handling harmonics from inverters
  • Frequent load fluctuation (cloud effect)
  • High ambient temperature operation
  • Continuous duty

✔ Built with:

  • Low-loss CRGO core
  • High insulation strength
  • Enhanced thermal design

🔷 Standards Compliance

🇮🇳 Indian Standards (IS)

  • IS 2026 – Power Transformer standard
  • IS 1180 – Efficiency (if applicable)
  • IS 335 – Transformer oil

🌍 International Standards

  • IEC 60076 – Power transformers
  • ANSI / IEEE (optional project-specific)

✔ Most manufacturers explicitly design IDTs as per IS 2026 & IEC 60076

🔷 Typical Technical Specs (Example)

  • Capacity: 2.5 MVA – 10 MVA
  • Voltage Ratio: 0.69 kV / 33 kV
  • Vector Group: Dyn11 / YNd11
  • Frequency: 50 Hz
  • Insulation Class: A / E
  • Tap Changer: OLTC / OCTC
  • Cooling: ONAN