When an industrial motor fails, the nameplate has almost everything you need to source a replacement. The trick is knowing which numbers actually have to match. Here's how to read a typical AC induction motor nameplate.
The specs that MUST match
- Power: HP (horsepower) or kW. 1 HP ≈ 0.746 kW.
- Speed: RPM at full load (e.g. 1750, 3500, 1160) — this tells you the pole count and must match.
- Voltage and phase: e.g. 230/460V three-phase, or 115/230V single-phase. Frequency: 60 Hz (US) or 50 Hz.
- Frame size: the NEMA (e.g. 56, 143T, 215T) or IEC (e.g. 80, 132M) frame sets the mounting dimensions and shaft — a wrong frame won't bolt up.
Enclosure and mounting
The enclosure type tells you how protected the motor is. The most common are ODP (Open Drip Proof — indoor, clean environments) and TEFC (Totally Enclosed Fan Cooled — dust, moisture, outdoor). Also note the mounting: foot-mount (rigid base), C-face or D-flange (bolts directly to a pump or gearbox), or a combination.
The numbers that help but aren't deal-breakers
- FLA (Full Load Amps): useful for sizing overloads and drives.
- Service Factor (SF): 1.15 means it can run 15% over rating briefly.
- Insulation class (B, F, H) and duty (Cont/S1) for thermal rating.
- Efficiency / NEMA Premium rating for energy compliance.
Why two motors with the same HP aren't always interchangeable
A 5 HP 1750 RPM 213T TEFC motor is not the same as a 5 HP 3500 RPM 184T ODP motor — same power, completely different speed, frame and protection. Always match power AND speed AND frame AND enclosure AND mounting before you buy.
Send us the nameplate
Snap a clear photo of the nameplate and send it over. We'll identify the motor, confirm the frame and mounting, and quote an exact or upgraded replacement across the major motor brands — in writing, with availability and lead time.