Chapter 24 Electrical Power - Extra Aircraft

EXTRA - FLUGZEUGBAU GmbHSERVICE MANUAL EXTRA 30024-30-00 DC-GENERATION(Refer to Figure 0 of Chapter 91) Power for the electricalsystem is provided by an alternator and/or the battery. Thealternator serves as the main component to power theelectrical system and charge the battery during normalconditions. The battery is used for starting the engine andpowering the electrical system when alternator power is notavailable (engine not running). The battery also powers theelectrical system in case of alternator failure.A rocker type master switch is used for energizing themaster relay, which connects power to the electrical system.The master switch is in series with the field switch sothat the complete electrical system can be cut of by meansof a master switch.The voltage regulator, receiving power from the battery viathe master switch in combination with the field switch,energizes the alternator field. With the alternator fieldenergized, the operating alternator will produce an outputto the electrical system. The voltage regulator varies theoutput voltage of the alternator to meet the requirements ofthe electrical system loads. An ammeter is installed into thesystem to provide an indication of current flow from or tothe battery.The negative side of the battery is connected to the aircraftsteel tube design (negative ground). This provides a groundfor the system through use of the steel tube design. Thepositive side of the battery is connected to the coil of themaster relay. This relay remains in relaxed state until themaster switch is placed to the ON-position. Placing themaster switch in the ON-position provides a ground for themaster relay energizing this relay. With the master relayenergized, a circuit exists from the battery through anammeter to the bus bar.The bus bar powers the electrical equipment and accessoriesfurnished on the aircraft. The energized master relaywill also allow power from the battery to the starter relay.Placing the field switch to the ON-position likewise willprovide a circuit from the bus bar through a 60 ampalternator and a 5 amp alternator field circuit breaker to thePAGE DATE: 31. January 1995CHAPTER 24PAGE 4