EUP Lot 11 Motors Final Report – DRAFT –October 2007 60 of 109 Figure 3-1 Motor efficiency vs. motor load for a standard 3-Phase, 4-pole, 11-kW, Squirrel-Cage Induction Motor. Typically, the maximum efficiency is obtained in the range 60-100% of motor load, although the maximum efficiency operating point is dependent upon the motor design. 3.3 Dosage of auxiliary inputs during use Larger motors are periodically lubricated. Most motors are subjected to repair upon failure (or show signs of imminent failure). In this operation new copper windings and bearings are installed. Old bearings and copper wire can be recycled.3.4 Economical Product Life (=in practice) Motor lifetime is influenced by many factors including number of operating hours, load factor including possible overloading, frequency of start/stop cycles, power quality and environmental conditions (temperature, vibrations, humidity, chemical pollutions). The average life of AC induction motors (including repairs) varies according to the motor power and is shown in Table 3-1. As mentioned earlier, small motors (up to 5 kW) are normally not repaired if they need to be rewound. However, since bearing failure is the most common cause of failure its replacement is done Nevertheless, motors with a high number of operating hours typically have a lower number of start-stop cycles leading to longer lifetime.
(1一般說來，馬達負載在60-100%之間可以有最大效率值表現，但運轉效率最高的那一點則依馬達設計來決定。)
2(大型馬達需要定期潤滑油。多數的馬達都是到了故障才要保養修理。(或是表現出有即將故障的徵兆) 這樣的運作之下，新的銅線繞組及軸承都需要重新換過安裝。舊的軸承及銅線則可以回收)
(3馬達的使用壽命受很多因素影響，包括運轉時數，負載因素則涵蓋了超載，起動/關閉的頻率，電力品質以及環境的影響(像是溫度，振動，溼度,化學污染等) 所以AC感應馬達的平均壽命(含維修)依照馬力數不同而改變，如TABLE 3-1所示。)
(4如之前所提到的，小馬達(指5HP以下)如果定子需要重新繞線，通常就不修理。然而，既然軸承故障常是是造成馬達無法運轉的原因，所以還是會更換軸承。不過，如果馬達的運轉時數很高，若是減少起動/關閉的次數可以延長其使用壽命。)
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