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What are the power sources for the DC electrical system? 5-1
- Batteries
- External power
- Generators
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What are the 4 separate parts of the electrical system? 5-1
28V DC (main & emergency), 115/26V AC, “wild” frequency 115V AC
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What makes up the 28V DC electrical system? 5-1
2 Main Batteries and 1 Emergency Battery, 2 Engine Generators, and External PWR
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How many Ni-Cad batteries does the Saab 340 have? 5-2
2
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What type of main batteries does the Saab 340 have? 5-2
24 volt 43 Amp hour Ni-Cad batteries
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Where are the main batteries located? 5-2
In the respective wing-fuselage fairing
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How are the batteries ventilated for cooling? 5-2
By ram air in flight, and fans on the ground
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What bus is used for battery charging? 5-2
Respective GEN bus with at least one generator online
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Which bus is the right battery connected to? 5-2
Right GEN bus
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What powers the Emergency Bus? 5-3
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? 5-3
When the L Battery power is lost
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Where is the Emergency Battery located? 5-3
Avionics rack
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What is the power source for the emergency power system? 5-3
Powered from the 28V DC system or the emergency battery
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What is indicated by an illuminated NO BAT START light? 5-3
Battery temp has reached 57ºC
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What is indicated by an illuminated BAT HOT light? 5-3
Battery has reached 71ºC
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What is indicated by an illuminated EMER PWR light? 5-3
Either the emergency bus is not supplied power or the battery had decreased below 24V
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What is the purpose of the Series/Parallel relay? 5-3
During a 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? 5-3
24 volt 5 amp hour lead acid battery
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What is indicated by an illuminated L/R BAT HOT light? 5-3
Associated battery temp has reached 71ºC
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What other light(s) would be on when a BAT HOT light is illuminated? 5-3
- NO BAT START
- BAT
- ELEC↑ on CWP
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What automatically happens when a battery temp reaches 71ºC? 5-3
BAT relay opens
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Can the battery supply power to the GEN bus with a BAT HOT? 5-3
Yes, in an emergency the BAT switch can be set to OVRD
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What would cause the GPU to automatically disconnect? 5-4
- Overvoltage (>31v)
- Under voltage (<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? 5-4
Voltage may drop to 7 volts
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What is the amperage of the 28V GPU? 5-4
1200-1600 amps
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What is the minimum voltage required to get the magnetic latch to close for GPU usage? 5-4
10 volts
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What does the blue EXT PWR AVAIL light indicate? 5-5
GPU is connected to the A/C and supplying at least 7 volts
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How many generators on each engine? 5-5&25
2 (DC & AC)
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When is the starter/generator acting as a starter? 5-5
During engine start when Ng is between 0-55%
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Are batteries being used for a cross generator start? 5-5
Yes, the batteries assist the generator to achieve a faster cooler start
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When is the GEN relay automatically opened? 5-6
- 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? 5-6
- When the respective Gen switch is off
- When external power is powering the A/C
- When a Fire handle has been pulled
- When engine Ng is less than 55%
- With a failure of the Gen
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How many electrical buses does the Saab 340 have? 5-6&7
27 (21 is incorrect)
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What minimum Ng is required to connect the starter/generator to the GEN BUS? 5-6
55%
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What is indicated by an illuminated L/R GEN light? 5-6
The respective Gen relay is open (gen offline)
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The starter/generators are rated at what voltage? 5-6
28 volts
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An illuminated GEN OV TEMP light on the overhead panel indicates what? 5-6
Generator is overheated (150º)
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Can the Generators be “online” with EXT PWR on? 5-6
No, the relay automatically opens
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What 3 conditions must be met for the GEN relay to close? 5-6
- 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? 5-8
The associated main bus is unpowered
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What is indicated by an illuminated L/R ESS BUS light? 5-9
Associated bus is not powered
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What is the purpose of the Bus Tie relay? 5-9
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? 5-9
The bus tie relay is closed
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What are three reasons the Bus Tie relay closes? 5-9
- EXT PWR is on
- Only one Generator is operating
- Either the LEFT or BOTH Batteries are on
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What is the purpose of the bus tie over-current relay? 5-9
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? 5-9
800 amps
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Can the Bus Tie over-current be reset manually? 5-9
Yes, through the K-1 reset button
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What is required to close the Utility Bus relay (RCCB)? 5-9
EXT PWR on or both generators on
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What powers the Emergency Avionics Bus? 5-9
The Emergency Bus, when the ESS AVION switch is on
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Where does the battery bus receive power from normally? 5-11
Gen bus
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The left battery is connected to which bus? 5-11
Start bus
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While on battery power alone what lights illuminate on the DC ELEC panel? 5-14
- 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? 5-15
- White EXT PWR
- L/R GEN
- L/R BAT
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What is the power source for the 115/26V AC system? 5-22
2 115/26V AC inverters powered by the DC system
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What is indicated by an illuminated INVERTER light? 5-22
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? 5-22
No CWP warning 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? 5-25
2 engine driven AC generators
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What is the “wild” frequency 115V AC power used for? 5-25
Ice protection
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Why is the AC GEN called the “wild” frequency? 5-25
Frequency varies with prop RPM, (460Hz to 640Hz)
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Where is the “wild” frequency generator located? 5-25
On the prop gear box
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What is the minimum prop RPM for an AC GEN to supply power? 5-25
1000 RPM
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If prop RPM drops below 1000 RPM, how is the AC GEN reset? 5-25
Automatically resets when prop RPM increases above 1000 RPM
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What does an illuminated AC GEN light indicate? 5-32
Generator is off line
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What items can be powered by the Emergency battery? 5-41
- Audio system backup power
- Bus tie CONN
- Engine Fire Warning
- Tailpipe hot Detection
- WEU Backup
- Emergency voltage indication
- Emergency Avionics Bus
- Stepdown from 24V to 6V for lighting of: Magnetic Compass, OBS, Pressurization, Standby Altimeter, Standby Attitude Indicator, Standby Airspeed
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What items are on the EMER AVIONICS BUS? 5-41
VHF COMM 1, Standby Attitude Indicator
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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 71ºC
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What cools the DC generator?
Ram air in flight and fans on the ground
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