General: Electrical system consists of two main buses, 28-volt DC system. Power is supplied to the buses from two engine generators and a 28 volt battery. The AC system is supplied by two 115 volts/400 Hz inverters and is used for autopilot operation only. The system is equipped with a cross-tie mechanism that allows both power sources to power both busses, with the use of the 'bus-tie' switch.
Batteries: 28 volt, 88 ampere/hour battery is feeding the main DC bus.
Two 75 amps generators, one driven by each engine. Each generator circuit is equipped with a switch relay that is operated by bus voltage through the generators switch. A voltage regulator automatically controls generator output within desired limits regardless of changes in engine RPM or electrical load. Each generator begins to operate and supply proper voltage to the Main DC Bus when its respective engine RPM is at or above approximately 950 RPM and the associated Generator Switch is in the ON position.
The Inverters switches, located on the RH overhead electrical panel, must be ON in addition to the BATTERY MASTER switch for the operation of the alternating current operated equipment.
Battery Master Switch is located on the LH overhead electrical panel. The generators switches are located on the RH overhead electrical panel.
Ammeters/Voltmeters:
Two ammeters, one for each generator, are provided to measure the amperage output of the generators. The ammeters are located on the RH side of the overhead electrical control panel. Each ammeter is equipped with a 'push to volts' button. A battery Voltmeter gauge shows battery voltage.
No-Charge / Low volt lights:
The CHRG light is located on the overhead electrical control panel. If the output voltage of the generators becomes less than that of the batteries, the respective reverse-current relay will prevent current flowing from the bus to the generator and will illuminate the generator light. When loading the buses (due to electrical systems operations), the light may illuminate for a short period of time. The Low volt light indicates Battery low voltage.
Bus-Tie:
Each generator feeds its respective bus. The Bus-Tie switch allows a single generator to feed both electrical buses. When the Bus-Tie switch is set to ON, electrical load is being regulated and equalized on both generators.
