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References: Motor Ratings, Speed Control and Positioners

  1. Variable-frequency drive - Wikipedia - Explains how a VFD converts fixed-frequency power to adjustable frequency, its energy savings on fans, and application concerns such as voltage spikes and bearing currents covered in this chapter.

  2. Affinity laws - Wikipedia - States the fan affinity laws: flow with speed, pressure with the square and power with the cube. These are the relationships behind the chapter's 45 Hz turndown example.

  3. Premium efficiency - Wikipedia - Covers premium efficiency motor programs in the USA, the IEC IE efficiency classes and how premium motors are designed, supporting the chapter's premium efficiency section.

  4. Energy-Efficient Electric Motors (3rd ed.) - Ali Emadi (editor), building on John C. Andreas's earlier editions - CRC Press - Treats motor efficiency as a design and application problem, linking losses, load point and life-cycle cost, the reasoning behind this chapter's "what does P buy" example.

  5. Electrical Installations in Hazardous Locations - Peter J. Schram and Mark W. Earley - NFPA - Explains the NEC class, division and group system with practical installation guidance, the classification a hazardous location motor must match on the order.

  6. FanPedia: The Fan & Blower Encyclopedia (PDF) - Twin City Fan - The chapter's primary source: motor specifications, speed, voltage, efficiency and duty (pp. 69-75), motor bases (pp. 76-78, 189) and motor positioners (pp. 148, 190).

  7. FanPedia online - Twin City Fan - Online edition of FanPedia; its Motors, Motor Bases and Motor Positioners galleries show the duty, base and positioner pages that this chapter turns into a complete motor line.

  8. Motor Standards for the Chemical Process Industry, IEEE-841 (FE-2100) - Twin City Fan - Engineering letter on the history and requirements of IEEE 841 severe duty TEFC motors, first issued in 1986. Explains why an IEEE 841 specification is stricter than plain severe duty.

  9. A Practical Guide for Using Variable Frequency Drive Systems in Air Movement Applications - Twin City Fan - White paper on VFD principles, selection, installation, building-management connection and commissioning for fans, extending the chapter's variable frequency drive section.

  10. NFPA 70, National Electrical Code (NEC) - NFPA - The code whose class, division and group system defines hazardous locations; the owner's classification under it is copied onto the order for a DFG motor.

  11. IEEE Std 45.1-2017, Recommended Practice for Electrical Installations on Shipboard - Design - IEEE - Part of the IEEE 45 shipboard series; subclause 13.2 recommends that squirrel cage motors of 10 to 500 hp comply with IEEE Std 841. Superseded by 45.1-2023 on the IEEE site; Twin City Fan's marine page (tcf.com/industries/marine/) names IEEE 45 marine-duty motors.