On a motor
Most induction motor nameplates carry these fields:
- Output — in kW, HP or both (1 HP ≈ 0.746 kW). This is mechanical power at the shaft.
- Voltage — for example 415 V for three-phase, 230 V for single-phase.
- Current (A) — the full-load current. Useful for setting overload protection.
- Speed (RPM) — around 2,880 for a 2-pole, 1,440 for a 4-pole, 960 for a 6-pole motor on 50 Hz.
- Frequency — 50 Hz in India.
- Connection — star (Y) or delta (Δ).
- Insulation class — a letter such as B, F or H, showing the temperature the insulation is designed for.
- Frame size — decides mounting and whether a replacement will fit.
On a transformer
A transformer plate usually shows:
- Rating in kVA.
- Primary and secondary voltages — what it takes in and gives out.
- Primary and secondary currents at full load.
- Phases and frequency.
- Vector group on three-phase units (for example Dyn11), which describes how the windings are connected.
- Cooling type — for example ONAN for oil-natural, air-natural.
- Impedance (%), and the serial number and year of manufacture.
What to send with an enquiry
A clear photo of the whole plate, taken straight on in good light, plus a note of what went wrong. If the plate is missing or unreadable, send the dimensions, a photo of the unit, and what it was running. That is usually enough to start.
General guidance only — every installation is different. For work on live equipment, use a licensed electrician. Last reviewed 28 September 2026.