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What are the power sources for the DC elctrical system
- Batteries
- External Power
- Generators
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What are the 4 separate parts of the electrical system
28V DC (main and emergency), 115/26V AC, "Wild" frequency 115V AC
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What makes up the 28V DC electrical system
- 2 main batteries and 1 emergency battery
- 2 Engine Generators
- External Power
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How many Ni-Cad batteries does the Saab 340 have
2
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What type of main batteries does the Saab 340 have
24 volt 43 amp hour Ni-Cad
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Where are the main batteries located
In the respective wing-fuselage fairing
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How are the batteries ventilated for cooling
By ram air in flight, and fans on the ground
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What bus is used for batter charging
Respective GEN bus with at least one generator online
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Which bus is the right battery connected to
Right GEN bus
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What powers the Emergency Bus
The L BAT BUS (batteries must be ON/OVRD) or the Emergency Battery
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When does the Emergency battery begin to power the EMER BUS
When the L Battery power is lost
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Where is the Emergency Battery located
Avionics rack
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What is the power source for the emergency power system
The 28V DC system or the emergency battery
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What is indicated by an illuminated NO BAT START light
Battery temp has reached 57C
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What is indicated by an illuminated BAT HOT light
Battery has reached 71C
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What is indicated by an illuminated EMER PWR light
Eighter the emergency bus in not supplied power or the battery has decreased below 24V
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What is the purpose of the Series/ Parallel relay
During battery start of the first engine the batteries are connected in series to produce 48 volts
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What type of Battery is used for the Emergency battery
24V 5 amp hour lead acid battery
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What is indicated by an illuminated L/R BAT HOT light
Associated battery temp has reached 71C
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What other light(s) would be on when a BAT HOT light is illuminated
- NO BAT START
- BAT
- ELEC^ on CWP
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What automatically happns when a battery temp reaches 71C
BAT relay opens
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Can the battery supply power to the GEN buss with a BAT HOT
Yes, in an emergency the BAT switch can be set to OVRD
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What would cause the GPU to automatically disconnect
- Overvoltage (over 31v)
- Under voltage (under 10v)
- Voltage drops below 10 volts with start switch held to L or R
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What is the voltage limit during a start with the start switch held to start
voltage may drop to 7 volts
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What is the amperage of the 28V GPU
1400-1600 amps
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What is the minimum voltage required to get the magnetic latch toclose for the GPU usage
10 volts
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What does the blue EXT PWR AVAIL light indicate
GPU is connected to the A/C and supplying at least 7 volts
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How many generators on each engine
2 (DC & AC)
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When is the starter/ generator acting as a starter
During engine start when Ng is between 0-55%
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Are batteries being used for a cross generator start
Yes, the batteries assist the generator to achieve a faster cooler start
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When is the GEN relay automatically opened
- GCU detects a malfunction (except overheating)
- External power is used
- Fire handle has been pulled
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When is the Gen relay light expected to be on
- Gen switch off
- External power connected
- Fire handle pulled
- Engine Ng is less than 55%
- Gen failure
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How many electrical busses does the Saab 340 have
21
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What minimum Ng is required to connect the starter/ generator to the GEN BUS
55%
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What is indicated by an illuminated L/R GEN light
The respective Gen relay is open (gen offline)
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The starter/ generators are rated at what voltage
28 volts
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An illuminated GEN OV TEMP light on the overhead panel indicates what
Generator is overheated (above 150C)
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Can the Generators be "online" with EXT PWR on
No, the relay automatically opens
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What 3 conditions must be met for the GEN relay to close
- EXT PWR must be off
- Engine start complete
- Gen field reset
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What is indicated by an illuminated L/R MAIN BUS light
The associated main bus is unpowered
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What is indicated by an illuminated L/R ESS BUS light
Associated bus is not powered
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What is the purpose of the Bus Tie relay
To connect the left and right busses to run off one power source
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What is indicated by an illuminated BUS TIE CONN light
The bus tie relay is closed
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What are three reasons the Bus Tie relay closes
- EXT PWR is on
- Only one Generator is operating
- Eigther the LEFT or BOTH Batteries are on
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What is the purpose of the bus tie over-current relay
To protect the Main Distribution system in case of a short
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Bus Tie relay opens if the over-current exceeds how many amps
800 amps
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Can the Bus Tie over-current be reset manually
Yes, through the K-1 reset button
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What is required to close the Utility Bus relay (RCCB)
EXT PWR on or both generators on
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What powers the Emergency Avionics Bus
The Emergency Bus, when the ESS AVION switch is on
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Where does the battery bus receive power from normally
Gen bus
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The left battery is connected to which bus
Start bus
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While on battery power alone what lights illuminate on the DC ELEC panel
- BUS TIE CONN
- L/R GEN
- L/R MAIN BUS
- EMER PWR (if BUS is below 24V)
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With the GPU powering the A/C what lights illuminate on the DC ELEC panel
- White EXT PWR
- L/R GEN
- L/R MAIN BUS
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What is the power source for the 115/26V AC system
2 115/ 26V AC inverters powered by the DC system
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What is indicated by an illuminated INVERTER light
Inverter switch is set to OFF or associated 115 volt inverter has failed
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With a failure of the 26V output of the inverter what warnings are given
No CWP warnings or cautions, but an RMI failure and VOR CDI failure will occur
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What is the power source for the "wild" frequency 115V AC system
2 engine drinven AC generators
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What is the "wild" frequency 115V AC power used for
Ice Protection
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Why is the AC GEN called the "wild" frequency
Frequency varies with prop RPM, (460Hz to 640Hz)
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Where is the "wild" frequency generator locator
In the prop gear box
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What is the minimum prop RPM for an AC GEN to supply power
1000 RPM
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If prop RPM drops below 1000 RPM, how is the AC GEN reset
Automatically resets when prop RPM increases above 1000 RPM
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What does an illuminated AC GEN light indicate
Generator is off line
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What items can be powered by the Emergency battery
- A udio System backup power
- B us-Tie relay connection function
- E ngine Fire detection L/R
- T ail Pipe Hot detection L/R
- W arning System backup power
- E mergency Volt Indicator
- E mergency Avionics Bus--- VHF Comm 1/ STBY Horizon
- S tandby instrument lighting
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What items are on the EMER AVIONICS BUS
VHF COMM 1, STBY Horizon
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What 3 conditions must be met for a battery relay to close
- BAT switch on
- EXT PWR off
- Battery temp below 71C
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What cools the DC generator
Ram air in flight and fans on the ground
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