EUP Lot 11 Motors Final Report – DRAFT –October 2007 61 of 109 Another critical factor is the bearing load which influences the bearing failures: The bearings of small and medium sized motors are typically designed for a nominal lifespan of 20.000 hours, with the lifetime being given by the equation: (L10h = aDIN x 1.000.000 / (60 x n) x (C/P)^3 with aDIN = correction factor depending on greasing conditions (typically aDIN = 2) n = rotational speed in rpm (1.500 for 4-pole) C = characteristic for the capabilities of the selected type of bearing P = average load of the bearing (calculated from the actual axial and actual radial force) Partial loading (i.e. reduction of P with a 60% average load) increases lifetime by a factor of 4.6, so for a typical machine the lifetime 92.600 hours. The life of small brushed DC motors is mainly limited by the lifetime of the brushes and of the commutator. In most applications where small power DC motors are used (e.g. small appliances) brushes are not checked for wear or replaced and so the motor’s life is equal to the lifetime of the brushes. General purpose DC motors operating at moderate speeds (750-1300 rpm) have an estimated 7500 hours brush life. The minimum life might be 2000–5000 hours, with 10000 h being about maximum. It is not uncommon, however, for motors with light or variable loads, such as machine tool motors, to have brush life that is less than 2000 hours [36]. The lifetime of Universal motors, which also use a commutator and brushes, rarely exceeds 1000 hours since they normally operate at much higher speeds. 3.5 End-of-Life actual behaviour (present fractions to recycling, re-use, disposal, etc) As a default, end-of-life behaviour fractions used in the MEEUP EcoReport for materials in all products across the EC will be used. 3.6 Best Practice in Sustainable product use High efficiency motors, such as EFF1, seem a good option for most industrial applications. In some situations the use of high efficiency motors may not be the best technical or economical choice, namely in the following cases: -In applications in which the number of operating hours is small (e.g. emergency pumps and ventilators) high efficiency motors may lead to higher lifecycle costs. -High efficiency motors, because of lower rotor slip, normally have a higher rotating speed than standard efficiency motors. In retrofit applications, when driving loads such as centrifugal pumps or fans, the power consumption of the high efficiency motor may be higher, because of the sharp increase of the mechanical power of the load with the motor speed (it grows approximately with the cube of the speed). In the future, IE3/Premium efficiency motors may be considered for applications with a large number of operating hours.

1另一個關鍵因素就是軸承的負載,負載大小通常會影響軸承的故障。中小型馬達的軸承一般設計使用壽命為2萬小時，軸承壽命的計算是由下列方程式提供.)

(2小型舉刷DC馬達的使用壽命主要是受舉刷及整流子的使用壽命限制。在大多數使用小型DC馬達的設備中，是不會檢查舉刷的損耗或更換舉刷，所以這些馬達的壽命就等於是舉刷的使用壽命)

(3泛用DC馬達在保守速度750-1300RPM運轉之下估計舉刷壽命約為7500小時。最低使用壽命可能為 2000-5000小時，最多到一萬小時。其實這並不尋常，然而馬達使用在少許或變動負載時，( 例如機械工具馬達)上，舉刷使用壽命會比2000小時還少。。

(4使用整流子及舉刷的通用馬達的壽命很少會超過1000小時，因為它們通常都是在高速度下運轉)

(5如同所預設的，在MEEUP EcoReport有關end of life behaviour fractions是全歐洲針對所有應用在產品的材料).

(6高效率馬達像是EFF1,對大多數的工業設備來說似乎是一個很好的選擇。但在某些情況下，使用高效率馬達可能在技術上或經濟上不是最好的選擇，如下所述:)

(7在某些運轉時數不高的設備上,例如緊急用的泵浦及通風設備,由於其使用壽命不高，高效率馬達反而會造成其成本上的浪費。高效率馬達由於其滑差較少，通常會比一般標準馬達的轉速還高。在式樣新的設備，當以高效率馬達帶動負載時(像是離心泵浦或風扇，其動能的消耗會更大，這是因為負載的機械動能隨著馬達的速度而急遽增加。(增加速度約為速度的立方)