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Division 3.2 Where the fan is supplied as ‘not final assembly’, the fan overall efficiency is calculated at the impeller’s optimum energy efficiency point, using the following equation:

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ηe = ηr · ηm · ηT · Cm · Cc

where:

  • ηe is the overall efficiency;

  • ηr is the fan impeller efficiency according to Pu(s) / Pa

    where:

    • Pu(s) is fan gas power determined at the point of optimal energy efficiency for the impeller and according to point 3.3 below;

    • Pa is the fan shaft power at the point of optimal energy efficiency of the impeller;

  • ηm is the nominal rated motor efficiency in accordance with Regulation (EC) No 640/2009 whenever applicable. If the motor is not covered by Regulation (EC) No 640/2009 or in case no motor is supplied a default ηm is calculated for the motor using the following values:

    • if the recommended electric input power ‘Pe’ is ≥ 0,75 kW,

      ηm = 0,000278*(x3) – 0,019247*(x2) + 0,104395*x + 0,809761,

      where x = Lg (Pe),

      and Pe is as defined in 3.1(a),

    • if the recommended motor input power ‘Pe’ is < 0,75 kW,

      ηm = 0,1462*ln(Pe) + 0,8381,

      and Pe is as defined in 3.1(a), where the electric input power Pe recommended by the manufacturer of the fan should be enough for the fan to reach its optimum energy efficiency point, taking into account losses from transmission systems if applicable.

  • ηT is the efficiency of the driving arrangement for which the following default values must be used:

    • for direct drive ηT = 1,0;

    • if the transmission is a low-efficiency drive as defined in 1(9) and

      • Pa ≥ 5 kW, ηT = 0,96, or

      • 1 kW < Pa < 5 kW, ηT = 0,0175 * Pa + 0,8725, or

      • Pa ≤ 1 kW, ηT = 0,89,

    • if the transmission is a high-efficiency drive as defined in 1(10) and

      • Pa ≥ 5 kW, ηT = 0,98,

      • or 1 kW < Pa < 5 kW, ηT = 0,01 * Pa + 0,93, or

      • Pa ≤ 1 kW, ηT = 0,94.

  • Cm is the compensation factor to account for matching of components = 0,9;

  • Cc is the part load compensation factor:

    • for a motor without a variable speed drive Cc = 1,0,

    • for a motor with a variable speed drive and Ped ≥ 5 kW, then Cc = 1,04,

    • for a motor with a variable speed drive and Ped < 5 kW, then Cc = – 0,03 ln(Ped) + 1,088.