A distribution transformer is a transformer that steps the utility’s distribution voltage, usually 11 kV, 22 kV or 33 kV, down to 433 V for factories, buildings and homes. It is the last transformer in the supply chain and runs 24 hours a day, so low losses matter most.
What it is: Three phase, oil cooled (ONAN), 11/0.433 kV, 22/0.433 kV or 33/0.433 kV, 25 kVA to 500 kVA, step-lap CRGO core, copper wound.
Best suited for: Utility-supplied factories, commercial buildings, housing, solar and pumping.
Steps HT (11, 22 or 33 kV) down to LT (415 V or 433 V).
Off-circuit taps, ±5% or ±7.5%; OLTC on request.
Step-lap CRGO core for low noise and low no-load loss.
Losses per IS 1180, designed to BEE 4-star / 5-star levels.
Routine tested in our in-house laboratory, with a test certificate, GA drawing and GTP.
| Parameter | Distribution Transformer |
|---|---|
| Rating | 25 kVA to 500 kVA |
| Primary voltage | 11, 22 or 33 kV |
| Secondary voltage | 415 V or 433 V |
| Phase and frequency | Three phase, 50 Hz |
| Vector group | Dyn11 (standard) |
| Cooling | ONAN |
| Winding | Copper |
| Core | Step-lap CRGO core for low noise and low no-load loss |
| Voltage regulation | Off-circuit taps, ±5% or ±7.5%; OLTC on request |
| Impedance | 4% (25 to 63 kVA); 4.75% (100 to 250 kVA); 5% (315 to 500 kVA) |
| Efficiency | 98% to 98.5% (25 to 100 kVA); 98.5% to 99% (160 to 500 kVA) |
| Losses | Low no-load and load losses per IS 1180; designed to BEE 4-star / 5-star levels |
| Temperature rise | Oil 35 °C; winding 45 °C |
| Insulation level | HV 95 kV BIL (11 kV system); LV 3 kV (1.1 kV system) |
| Design ambient | 50 °C, 100% humidity |
| Oil and protection | High BDV oil; moisture-resistant insulation; anti-corrosion, tropicalised finish |
| Standards | IS 1180 (Part 1), IS 2026 |
| Fittings | Conservator, breather, oil level gauge, OTI, WTI, Buchholz relay, cable box or bushings |
Off-circuit tap switch, Buchholz relay, oil and winding temperature indicators, cable box or bushings, and marshalling box are available as options. GA drawings, rating plate drawings and guaranteed technical particulars (GTP) are available on request.
New HT connection (11 kV or 33 kV) for a factory or building
Manufacturing plants: main HT connection and plant power
Commercial buildings and housing: building supply from 11 kV
Solar power plants: inverter output to grid connection
Water supply and agriculture: pumping stations
Railways and infrastructure: station, depot and site supply
Our application engineers can size the unit for your load and supply. We also make servo voltage stabilizers, industrial rectifiers, chemical earthing electrodes for transformer neutral and body earthing, and lightning arresters for the substation.
More questions are answered on the transformers page, which covers kVA sizing, losses, testing and how to compare transformer manufacturers.
| Product | What it is | Best suited for |
|---|---|---|
| HT AVR Transformer | Copper-wound “two-in-one” HT stabilizer and transformer for 11, 22 or 33 kV, holding the LT output within ±1%, for indoor or outdoor installation, 500 kVA to 10 MVA | Industrial plants on unstable HT supply, hospitals, data centres, process lines |
| LT Step-Down Transformer | 415 V down to 230 V, 110 V or as specified, 25 kVA to 2500 kVA, dry type or oil cooled | Lighting, controls, imported equipment, separate LT circuits |
| LT Step-Up Transformer | 415 V up to 690 V or as specified, 25 kVA to 2500 kVA | Motors and machines rated above 415 V, long LT cable runs |
| Dry Type Transformer | Three phase, ventilated, cast resin or VPI, 11 kV or 33 kV class, 25 kVA to 500 kVA, oil-free and fire-safe | Indoor substations, high-rise buildings, hospitals, malls, metro and data centres where oil is a fire risk |
| Furnace Transformer | Heavy-duty transformer feeding medium-frequency induction furnace panels, 25 kVA to 500 kVA, built for high currents and frequent short circuits during melting | Steel melting shops, foundries and alloy plants |
Send your kVA rating, HT and LT voltages, vector group and site location. Our engineers will reply with a techno-commercial offer, guaranteed losses, a GA drawing and the delivery schedule.