(5) Application of 28 volt dc to close, allows momentary energizing of the coil . when the breaker closes, the coil deenergizes through the auxiliary contact and the breaker is held closed by the permanent magnet. Application of 28 volt dc to trip. Reverses the polarity of the coil and the contactor opens assisted by the spring. The coil deenergizes through the auxiliary contact.

28伏直流電關(guān)閉的應(yīng)用，允許線圈瞬時接通。當(dāng)跳開關(guān)閉合時，線圈通過輔助觸點斷電，跳開關(guān)通過永久磁鐵被保持在閉合位。 28伏直流電松開的應(yīng)用，將線圈極性反向，觸點在彈簧的幫助下打開。線圈通過輔助觸點斷電。

(6) The 115 volt ac, 400HZ, 3-pahse power from an external source (ground power unit ) can also be supplied to the airplane for systems use. The external ac power system consists of an external power receptacle, bus protection panel, two external power contactors, relays, switches and indicating lights. The ac external power receptacle is located on the right side of the airplane, forward of the nose wheel well, the bus protection panel (BPP) is used for control and protection of the airplane circuits connected to external power. The two external power contactors connect 115 volt ac, 400Hertz, 3-phase power to the distribution system from external power source.

從外部電源的（地面電源） 400HZ，115伏三相交流電也能夠提供到飛機(jī)上供系統(tǒng)使用。外部交流電源系統(tǒng)包括一個外部電源插座，匯流條防換板，兩個外部電源接觸器、繼電器、開關(guān)及指示燈。外部交流電源插座位于飛機(jī)右側(cè)、前輪艙前方。匯流條防護(hù)板用來保護(hù)與外部電源連接的飛機(jī)線路。兩個接觸器將外部來的 115伏， 400HZ的三相交流電源接到分配系統(tǒng)。

(7) The 115 volt ac system is supplied by two engine driven generators, APU driven generator or external power. The powr is connected to the generator main busses by engine generator breakers. APU breakers and external

power contactors. Power is also supplied to two transfer busses through transfer relays. External power can be supplied to the external ac bus and the ground service bus (this bus is used for servicing of the airplane). The ground service bus can also be supplied from generator bus NO.1.
115伏交流電源由兩臺發(fā)動機(jī)驅(qū)動的發(fā)電機(jī)、 APU發(fā)電機(jī)或地面電源提供。它被發(fā)動機(jī)跳開關(guān)、 APU跳開關(guān)或地面電源觸點連接到發(fā)電機(jī)主匯流條上，它也可以通過轉(zhuǎn)換繼電器接到兩個轉(zhuǎn)換匯流條上。外部電源也能夠供到外部交流匯流條及地面服務(wù)匯流條上。地面服務(wù)匯流條也能夠從一號發(fā)電機(jī)匯流條供電。
(8) The 28 volt ac system is obtained through transrformers from main, transfer ,and ground service busses. The 28 volt dc power is supplied from the battery and transformer rectifiers to the battery bus and two dc busses. The power is connected to the busses by relays. The battery charger is supplied with power from the 115 volt ac system. The electronic system power is supplied from the 115 volt ac and 28 volt dc system. The standby ac and dc busses are powered normally from the generated ac and dc power. Alternately, the battery supplies power to the standby system. The standby power components are located in the electronics compartment, P6 panel and p5 panel .the purpose of the standby power distribution is to provide 115 volt ac and 28 volt dc power to essential system during absence of normal supply.