Card Set Information
B737 electrical systems
B737 electrical systems
How is the electrical system managed when a fault occurs?
The electrical system monitors itself for faults and automatically disconnects a Generator Bus from its power source when electrical power is out of limits.
What is the normal source of power for an AC TRANSFER bus?
Respective GEN bus
Conditions: Both engine driven generators on line; APU shut down; BUS TRANSFER switch in the AUTO position. Which buses are not powered if #2 engine driven generator trips off?
Generator bus and Main bus on failed side.
What is the power source for TR-3
Main Bus #2
What is the normal source of power for TRs 1 and 2?
Respective AC TRANSFER buses
What is the backup source of power for DC Bus 1?
How does the TR 3 disconnect relay normally function?
Automatically opens during an A/P or FD approach at glide slope capture.
What is the power source for the Hot Battery bus when all aircraft buses are powered?
What is the normal source of power for the AC Ground Service bus?
#1 Generator Bus
What is the normal source of power for the Battery bus?
What is the normal source of power for the Battery charger?
AC GROUND SERVICE bus
The aircraft is in flight with only the battery for electric power. Where does the power come from for the AC and DC Standby buses?
Static Inverter for the AC Stanby bus, and Battery bus for the DC Standby bus.
What is the alternate power source for the Battery bus?
Hot Battery bus
What is the alternate source of power for the Hot Battery bus when the normal power source is not available?
Battery. Most of the time is 28V from batt charger, rarely 24V from battery (the rare is the backup).
What is the alternate power source for the Battery Charger?
Main Bus 2
What is the purpose of the CSD?
Change variable engine speed into constant generator drive speed.
Which DC selector positions display DC amps?
TRs 1,2,3 and BAT. Just the components not the buses can give amps (flow).
How do you check the battery condition?
Turn on the battery switch, place DC meter selector to BAT, check volts within limits.
How is a failure of TR 1 and TR 3 disconnect relay closed?
0 amps, normal volts indicated on the DC meters at the TR 1 position.
How would a failure of the static inverter be indicated during the standy power check?
0 volts on the AC volt meter and 0 cps on the AC frequency meter.
What is the function of the ON position of the galley power switch?
Powers all galleys when both Gernerator buses are powered. Galley easily load shed, need both gens.
With the battery switch ON, what happens?
Both the Battery bus and Switched Hot Battery bus are powered
How do you establish power to the Ground Service Bus on the ground?
GRD POWER AVAILABLE light on, GROUND SERVICE switch on
What does an illuminated STANDBY PWR OFF light indicate?
The AC Standby bus is unpowered.
What is the function of the AUTO position of the STANDBY POWER switch with loss of all AC power?
Allows the BATTERY BUS to be the source of power for both Standby buses inflight.
What does an illuminated CSD HIGH OIL TEMP light indicate?
CSD oil temperature exceeds operating limits.
How do you disconnect a CSD?
Hold generator drive disconnect switch to DISCONNECT momentarily. Te CSD may be re-engaged on the ground by maintenance.
What does an illuminated GRD POWER AVAILABLE light indicate?
Ground cart is plugged in and external bus is powered. On the -500 just plugged in, chks quality when put on bus; NG good quality.
What is the function of tthe ON position of the GRD PWR switch?
Connects ground power directly to both Generator buses if the ground power quality is correct.
What is the function of the OFF position of the BUS TRANSFER switch?
Prevents operation of bus transfer relays, prevents battery charge from switching to Main Bus 2 and opens TR3 disconnect relay. Doesn't stop the HEAVY stuff from working.
What does an illuminated BUS OFF amber light indicate?
The respective Generator bus is unpowered.
What does an illuminated TRANSFER BUS OFF light indicate?
Respective Transfer bus is unpowered.
What is the function of the APU Generator switches?
Connects gernerator ouput to Generator bus if power quality is correct.
In flight, the AC Ground Service bus is powered by:
Generator Bus 1
Engine driven generator maximum load is:
TRUE or FALSE
In the air, galley power is available only when both generator buses are powered.
TRUE or FALSE
All power sources to a GEN BUS must be manually connected through the movement of a switch.
What are the TR operating parameters?
With the loss of all generators, a fully charged battery can supply power to the stanby buses for at least_____.
On the ground, alternate power for the Stanby buses requires:
Standby power switch at BAT
With loss of normal AC power in flight, power for the Standby AC and Standby DC buses is automatically available from:
Battery bus and Static inverter
A ground service bus control switch, labeled "GROUND SERVICE" is located on the:
Forward FA panel
When is an amber "BUS OFF" light extinguished?
When the corresponding GEN bus is powered.
What is the maximum engine generator electrical load limit?
What is the minimum battery voltage for an APU start?
When a CSD LOW OIL PRESSURE or HIGH OIL TEMP light comes on, the system annunciator and Master Caution lights illuminate_______.
Which light is illuminated when the External AC Bus is powered?
GRD POWER AVAILABLE