Motor Reference Standards: Rated Speed vs. No-Load Speed

Motor Reference Standards: Rated Speed vs. No-Load Speed

Product standards, nameplates, contracts, testing, customs clearance, and motor selection must all be based on the 【Rated Speed】.

Simple Distinction

1. Rated Speed (value listed on the nameplate) – Official Standard Value

The speed at which the motor operates under rated load and at rated voltage.

This is the speed value printed in catalogs, on nameplates, and in technical agreements, and is used for motor selection, acceptance testing, and determining compliance.

2. No-Load Speed

The speed when the motor is running without a load; this speed is higher than the rated speed.

No-load speed is an actual operating condition parameter; it is not used as a judgment criterion but serves only as an internal reference and is not printed on the nameplate.

Practical Scenarios

• When signing technical contracts, preparing customs declaration documents, or drafting specifications: Enter the rated speed.

• When determining compliance during factory acceptance testing: Check the rated speed under rated load.

• The speed obtained by measuring the motor’s idle rotation on your own is merely the no-load speed and cannot be used to compare against the nameplate.

Permanent magnet brushed DC motors: No-load speed > rated speed; the speed will drop once a load is applied.

For external standards, refer to the rated speed; the no-load speed is merely a measured value during idle operation and is not used as a basis for standards.