IEC TS 60034-31 pdf free download
IEC TS 60034-31 pdf free download.Rotating electrical machines – Part 31: Selection of energy-efficient motors including variable speed applications – Application guidelines.
4 Background
4.1 General
This clause introduces the importance of energy efficiency and the high energy saving potential related to the use of electric motors and variable frequency drives.
The global total amount of greenhouse gas emissions (GHG) was 49 gigatons (Gt) of CO2 equivalents in 2010. The energy sector, which primarily involves electricity and heat production, had the largest share of 35 % of the GHG emissions [1]1. Coal was by far the largest energy source for electricity production in 2015, with a share of 43 % of the total global generation of 20 000 TWh, followed by gas, hydro and nuclear with a share of 19 %, 15 % and 12 %, respectively [2]. The average efficiency rate of coal power plants in 2017 was 33 % [3].
As mentioned in the introduction, about 50 % of the total global electric energy consumption is converted by electric motors, which are the largest consumers of electricity per component type [4-5]. Industrial motors alone accounted for around 30 % of all electricity consumption in 2016, as seen in Figure Ia [4-6]. Another 20 % of electricity is consumed by electric motors in other sectors like commercial, residential, transport and agriculture [6]. Therefore, electric motors and especially motors operated by variable frequency drives (VFD) are key components for achieving immense electricity savings. The installed base of industrial low voltage motors in the power range between 0,12 kW and I 000 kW is estimated to be more than 750 million units [7].
NOTE 1 The most part of the electric energy consumed by electric motors is converted into mechanical energy to the driven equipment. The rest is converted into heat, that is losses. The expression “energy consumption is used in this document as an alternative to “energy conversion, since it is a commonly used expression even though the definition is according to the aforementioned sentence.
Currently, the share of motors equipped with electronic speed control is only about 12 % of the installed motor base, as illustrated in Figure lb [8]. It is estimated that it would be beneficial for energy savings that this share should be more than 50 %. Replacing a direct on line motor with a new motor with a higher efficiency class is a simple measure to improve energy efficiency in most applications. However, a greater energy saving potential is associated with speed control, when this can be used to replace less efficient mechanical control equipment like throttle valves for pumps [9]. When taking life cycle costs into account, investments in energy saving measures can often pay off within just a few years, or even months. The cost of electricity accounts for up to 96 % of the total life cycle cost of a motor driven system, while the investment and installation costs only account for around 2,5 % and maintenance costs account for the remaining 1,5 %, as shown in Figure Ic [8]. Taking a holistic life cycle cost approach rather than a component price optimization strategy can be highly profitable, when investing in motors and drives. Pump systems presently account for more than 25 % of the worldwide electric energy consumption in the industrial sector. It is estimated that around 40 % of this energy could be saved. Centrifugal pumps in particular, accounting for a 73 % market share, represent great potentials for energy savings, as some 75 % of these pumps are oversized [8]. Fan systems, likewise centrifugal pumps, also have a load profile that rises quadratically with speed, resulting in a cubic power profile with vast energy saving potentials when run with variable speed control. These two applications alone account for 52 % of the low voltage industrial motor market [7]. The estimated global market shares of industrial electric motors per efficiency class in 2020 is shown in Figure Id [10], while their respective historic developments in the time period 1995 to 2020 are shown in Figure 2 [10-12]. IEC TS 60034-31 pdf download.
