Distribution Transformer Specifications for India: Voltages, Frequency and IS 1180
Most specification errors on India projects are not exotic. A unit is ordered against 11 kV and lands on a 22 kV feeder. A 60 Hz design gets quoted into a 50 Hz network. Both are avoidable, and both cost weeks. India’s distribution voltages and frequency are fixed — confirm them before the drawing is released.
Voltages used on Indian distribution networks
- Primary (HV) side: 3.3, 6.6, 11, 22 and 33 kV are the common levels.
- Secondary (LV) side: 415 V three-phase four-wire, giving 230 V single-phase.
- Frequency: 50 Hz across the country.
- Confirm the actual feeder voltage at the site, not the nominal system figure.
What IS 1180 covers
IS 1180 is the Indian Standard for outdoor oil-immersed distribution transformers, published by the Bureau of Indian Standards. It sets out ratings, losses and construction requirements for the distribution class. Where a project calls for IS 1180, we build and test against it; where it calls for IEC 60076, we work to that instead. The standard is always named on the order, never assumed.
What to confirm before ordering
- Rating in kVA, matched to the inverter or load total.
- Primary and secondary voltage, and whether the primary is selectable.
- Frequency — 50 Hz for India.
- Vector group, most often Dyn11.
- Short-circuit impedance, to suit the fault level on the board.
- Cooling class and tapping range.
- Ambient conditions, altitude and enclosure requirements.
Send the specification and we will confirm what we can build, the delivery schedule and the documents that ship with the unit.
Send us the specification
Rating, primary and secondary voltage, frequency, quantity and the application. We answer within one working day.
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