[49APU] 737系列APU电源电门为何有两个？

引用第7楼kimi于2010-03-01 22:08发表的  :
6楼上说的没错
300我不清楚，只针对NG飞机，如果在地面电转APU电时，只需扳其中一个电门就好(注意前提是先前电为地面电，如果为发动机供电，则情况不同)，但我们一般要两个都扳一下，因为只扳一个，两个BTB虽然都闭合了，但没扳一侧电门对应的SOURCE OFF灯就会点亮，所以扳另一个电门就是为了使这个灯灭掉。
另外，为什么设计两个电门，AMM PI里有详解，这里选取，仅供参考：
There are two switches because there are two bus tie breakers (BTBs).
You use the APU GEN switches to supply power to the AC transfer buses. There are two switches because there are two bus tie breakers (BTBs) that supply power to the AC transfer buses. Both AC transfer buses will receive APU power with operation of just one APU GEN switch if both AC transfer buses do not have power initially or if external power is the only source on the AC transfer buses. If the AC transfer buses do have power initially from two power sources, (for example both IDGs) then only the AC transfer bus on the same side as the APU GEN switch you operate will energize with APU power.
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