Define the driven equipment
Begin with the machine and its operating cycle. For a replacement, send a readable nameplate photograph alongside mounting and coupling dimensions. A matching power rating does not establish that a motor will fit or suit the duty.
How an induction motor works
In a three-phase induction motor, the stator windings create a rotating magnetic field. This induces current in the rotor; their interaction produces torque at the shaft. In normal motoring operation the rotor runs slightly below the field’s synchronous speed. That difference is called slip.
Supply frequency and pole count determine synchronous speed. Actual shaft speed also depends on the motor and its load. This is why a replacement enquiry should include the rated speed from the nameplate, not just the power rating.
Further reading
Independent technical references; no supplier partnership or endorsement is implied.
Prepare the motor schedule
| Requirement | What to provide |
|---|---|
| Electrical | Rated output, voltage, frequency, phases, speed and current from the existing nameplate where available. |
| Duty & starting | Operating cycle, starts per hour, starting method and driven-load details. |
| Mechanical fit | Frame and mounting designation, foot or flange dimensions, shaft size, key and coupling details. |
| Environment | Ambient range, altitude, indoor / outdoor exposure, ingress protection and corrosion conditions. |
| Operating needs | Rotation, terminal-box position, temperature sensors, bearing arrangements and maintenance access. |
| Energy performance | Required efficiency class and applicable local requirements for the proposed motor. |
Replacement review
- Photograph the nameplate, terminal box and installed motor.
- Record the machine make and model plus available drawings.
- Note any previous overheating, vibration, starting or bearing issues.
- Identify the shutdown window and the latest acceptable arrival date.
From enquiry to proposal
Request a proposed data sheet, dimension drawing, electrical connection information and duty confirmation. Compare deviations explicitly before accepting a substitute.
Download the motor enquiry worksheetFurther reading
Independent technical references; no supplier partnership or endorsement is implied.