In this guide
The motor nameplate is the single best source of information for ordering a replacement motor or sizing a drive. Most of the fields are standard, and a few are easy to misread.
The fields
| Field | What it tells you |
|---|---|
| kW (or hp) | Rated shaft output power |
| V and connection | Supply voltage. A motor may show two values, for example 400 Δ / 690 Y, for different connections |
| A | Full-load current at that voltage. This is the number used to size a drive, starter and overload |
| Hz | Rated supply frequency. 50 Hz in South Africa |
| rpm | Rated speed at full load, which indicates the pole count |
| cos φ | Power factor at full load |
| IE class | Efficiency class: IE1 standard up to IE4 super premium |
| IP | Ingress protection: dust and water |
| Ins. class | Insulation class. Class F is common. It sets the temperature the windings can tolerate |
| S1 | Duty type. S1 means continuous duty |
| Frame | The IEC frame size, for example 132M. The number is the shaft height in millimetres |
| IM B3 / B5 / B14 | The mounting arrangement: foot, large flange or small flange |
Speed and poles
A four-pole motor on 50 Hz has a synchronous speed of 1500 rpm and a nameplate speed slightly below that, typically 1400 to 1485 rpm (lower for small motors, closer to 1500 for large ones). The nameplate speed is the quickest way to find the pole count. Our motor speed calculator does this for you.
Two voltages, two currents
A dual-voltage motor lists a current for each connection. Use the current for the connection you will use on site. On a 400 V supply a motor marked 400 Δ / 690 Y is wired in delta.
What decides whether a replacement fits
- Power, speed and voltage
- Frame size and mounting arrangement, which decide whether it bolts in
- Shaft diameter and length, which decide whether the coupling fits
- Protection level and duty, especially in dusty or wet areas
- Anything special: brake, encoder, thermistors, forced cooling
What to send us
- A clear photo of the nameplate, front on
- Any extra labels, for example a brake or encoder label
- Whether the motor runs from a drive
- The application, for example conveyor, pump or fan