Industrial Engineer · phase 9 of 16
Horsepower / Kilowatt Rating
Nominal motor-power class for the drive, secondary to verifying motor current, duty, voltage, and overload requirements.
The Explain card
- Plain English
- The horsepower or kilowatt rating is the nominal motor size the drive is meant for. It is a convenient label, and the drive itself only knows about volts and amps.
- Example
- A 10 horsepower drive is offered for a 10 horsepower motor. If that motor is a high efficiency design with unusual current, or runs constant torque with heavy overloads, the 10 horsepower drive may be too small.
- Why it matters
- Sizing by horsepower alone is the classic way to under size a drive, because the label assumes a typical motor on a typical variable torque load. The current rating, the duty rating and the environment decide, and the horsepower on the box only gets you to the right shelf.
- Hook
- A label for the catalog, never a specification for the motor.
Where it sits in the deck
Phase 9: VFD Ratings, Sizing, and Motor Data
Nameplate arithmetic, where the currents, voltages and duty ratings decide whether a drive can actually run the motor you bolted it to.
