API 541 Third Edition: an improved purchasing specification [for electric motors]

The American Petroleum Institute (API) Standard 541, Third Edition, is a standard that covers the minimum requirements for form-wound coils, and squirrel cage rotor induction motors 250 horsepower and larger (this is generally above the NEMA 440 frame size). The purpose of this API 541 Standard is to serve as a comprehensive purchasing specification that can be used by specifiers of high-performance motors. Although this specification is tailored to the needs of the petroleum industry, it can readily be applied by all industries. The API 541 Standard authors recommend that all engineers who specify motors obtain a copy of the Standard and use it in their motor purchases. They believe that it is both a useful guide and a valuable resource for the purchasing of high-performance motors.