C 12 Electrical Power System Final Wor
Electrical Power System
By Cameron Cooper
The electrical system on the C-12 is a 28 volt system. It also has single phase, 400 hertz, 115 volt and 26 volt AC power systems. The AC power is provided by two inverters. The main 28 volt electrical power for the C-12 is supplied from any combination of: -One 28 volt, 42 amp hour lead acid battery or One 28 volt, 34 amp hour nickel cadmium battery (depending on the model); -Two parallel 28 volt, 250 amp starter generators on each engine; -One external (ground power) 28 volt, power receptacle. The battery is used as a back up to the starter generators while in flight or can be used for ground operations. It is connected to the hot battery bus regardless of the battery relay position. The hot battery bus powers the engine fire extinguishers, firewall shutoff valves, entry and cargo lights, clocks, modifications, ground communications, RNAV memory to older avionics and standby boost pumps. The hot bus also supplies the battery power relay that allows the battery to run other electrical systems not connected to the hot bus. External 28v DC power may be supplied to the aircraft through an external power receptacle on the underside of the right wing, just outboard of the nacelle. This is used only on the ground, primarily for maintenance but could also be used if the battery is dead. Once connected, the ground power relay must be turned on to supply power to the system. The ground power relay uses power from the external power (not from any of the DC buses) to energize the relay. This is done because in a situation where the battery was dead, the battery could not energize the ground power relay. The battery or ground power can be used for starting either engine via the starter generator. This is done by passing power through the main battery bus (starter bus) and is controlled by the starter relay for the corresponding engine. Once one engine is started, the generator comes online and can then be used
By Cameron Cooper
The electrical system on the C-12 is a 28 volt system. It also has single phase, 400 hertz, 115 volt and 26 volt AC power systems. The AC power is provided by two inverters. The main 28 volt electrical power for the C-12 is supplied from any combination of: -One 28 volt, 42 amp hour lead acid battery or One 28 volt, 34 amp hour nickel cadmium battery (depending on the model); -Two parallel 28 volt, 250 amp starter generators on each engine; -One external (ground power) 28 volt, power receptacle. The battery is used as a back up to the starter generators while in flight or can be used for ground operations. It is connected to the hot battery bus regardless of the battery relay position. The hot battery bus powers the engine fire extinguishers, firewall shutoff valves, entry and cargo lights, clocks, modifications, ground communications, RNAV memory to older avionics and standby boost pumps. The hot bus also supplies the battery power relay that allows the battery to run other electrical systems not connected to the hot bus. External 28v DC power may be supplied to the aircraft through an external power receptacle on the underside of the right wing, just outboard of the nacelle. This is used only on the ground, primarily for maintenance but could also be used if the battery is dead. Once connected, the ground power relay must be turned on to supply power to the system. The ground power relay uses power from the external power (not from any of the DC buses) to energize the relay. This is done because in a situation where the battery was dead, the battery could not energize the ground power relay. The battery or ground power can be used for starting either engine via the starter generator. This is done by passing power through the main battery bus (starter bus) and is controlled by the starter relay for the corresponding engine. Once one engine is started, the generator comes online and can then be used