But there are different standards for high-efficiency motors. For example, according to the four efficiency classes for 10-hp motors defined by the International Electrotechnical Commission, from the lowest class, IE1, to the highest, IE4, the motors of each class are respectively 21 %, 15 % and 15 % more energy efficient than those of the class below.
而高效率馬達又有不同的標準，以「國際電工委員會」訂定的「10 馬」4 級標準為例，其中從最高級的 IE4 到一般級的 IE1，各比前一級節能 15 %、16 %、21 %。