(6) The start system interfaces with the sequencing oil pressure switch, speed switch, APU control unit and APU switch. During APU start, the starter is energized and APU rotates. The ignition exciter is energized by the action of the sequencing oil pressure switch(this switch ensures that combustion cannot be initiated during an APU start until a minimum lubricating oil pressure has been buildup during APU start, with increasing oil pressure, this switch closes at 4 psig oil pressure and provides 28 volt dc power to the fuel solenoid valve and the ignition exciter). The starter and ignition circuits are de-energized by the action of the speed switch during APU engine acceleration. During normal engine operation, the exciter remains de-energized.

起動系統(tǒng)連接著程序化的滑油壓力開關(guān)、速度開關(guān)、 APU控制組件及 APU開關(guān)。 APU起動期間，起動器被接通， APU轉(zhuǎn)動。點火勵磁器通過程序化的滑油壓力開關(guān)（此開關(guān)確保在 APU起動到建立最小的滑油潤滑壓力期間不會燃燒。在 APU起動期間，隨著滑油壓力增加，當(dāng)滑油壓力達到 4PSIG時，開關(guān)關(guān)閉，并且提供 28伏直流電給燃油電磁活門及點火勵磁器）動作被接通。起動器及點火線圈在 APU發(fā)動機加速期間通過速度開關(guān)被釋放。在發(fā)動機正常操作期間，勵磁器保持斷開。

(7) The APU exhaust conducts the engine exhaust gas overboard and reduces the noise level of the high velocity gas flow. The exhaust duct consists of a

heat shield and a muffler. The muffler is inside the heat shield. A felt metal liner is installed on the inside surface of the muffler for noise reduction. At the forward end ,the heat shield has a drip pan and is supported by the engine shroud. There si a gap between the muffler and the APU engine exhaust. At the aft end ,the exhaust duct is supported by the aft fairing .
APU排放口引導(dǎo)發(fā)動機排出氣體到外面并降低高速氣流的噪音。排放管道包括一個加熱保護罩和一個消音器。消音器安裝于加熱保護罩內(nèi)部。一個絕緣金屬墊片消音器內(nèi)表面上，用來降低噪音。在加熱器前端有一個集油盤并被發(fā)動機保護罩支持。在消音器與 APU發(fā)動機排氣口之間有一個間隙。排氣管道后端由后整流罩支撐。
LESSON 19 AUXILIARY POWER UNIT（2）
一、單詞
首先  Primarily 供給  Furnish 接線端  teminal
中線  Neutral 導(dǎo)線  Lead 在 …外面  Outside
放電器  Discharger 開縫的  slotted 頻率  Frequency
得到  Achieve 跳開關(guān)  Breaker 閉合  Closing
松開  Tripping 永久磁鐵  Permanent magnet 幫助  Assist
鎖定  Latch 彈簧  Spring 保持  hold
觸點  Contact 接觸器  Contactor 信號  Signal
獲得  Gain 應(yīng)用  Application 允許  Allow
短暫的  Momentary 通電  Energize 線圈  Coil
極性  polarity 插座  Receptacle 匯流條防護  Bus protection panel
充電器  Charger 主要的  Essential 缺席  Absence
柱螺栓  stud

二、TEXT
(1) the APU driven generator is mounted on the foreard face of the APU accessory drive gearbox. The APU generator produces the AC power required by the airplane systems primarily for ground operation, the generator can also be used as a backup generator in flight. APU is used to furnish 60 KVA of electrical power on the ground and used as AC power source of 50 KVA in flight.