Electrical Panel

Question 1

TR UNIT light

Answer 1

• illuminates on ground if any TR has failed

- illuminates in flight if TR1 failed or TR2 and TR3 failed

Question 2

ELEC light

Answer 2

• operates only on the ground if a fault exists in the DC or the standby power system

Question 3

DC METER SELECTOR

Answer 3

• voltage (DC VOLTS) and load (DC AMPS) show on the alphanumeric display when you put the selector in the BAT position or any TR position
- BAT, TR1, TR2, and TR3
• STBY PWR = volts of the dc standby bus
- no amp indication since this is not a source of power
• BAT BUS = volts on the battery bus
- no amp indication since this is not a source of power
• BAT = volts and amps from respective battery charger or battery whichever is greater
- BAT position only
- amps vary with the state of the battery charge
- normal indication is zero, indicating a fully charged battery
• TR1 & TR2 = volts from DC bus 1 & 2 and amps from respective TR
• TR3 = volts and amps directly from TR3

Question 4

AC METER SELECTOR

Answer 4

• the alphanumeric display shows these parameters for the 3 generators:
• voltage (AC VOLTS)
• load (AC AMPS)
• output frequency (CPS FREQ)
• the alphanumeric display shows only voltage and frequency when you select one of these:
• STBY PWR
• GRD PWR
• INV

Question 5

BATTERY switch
OFF
ON

Answer 5

OFF

• removes power from the battery bus and switched hot battery bus when operating with normal power sources available (standby power switch in OFF or AUTO)
• removes power from the switched hot battery bus, battery bus, static inverter, AC standby bus, DC standby bus when battery(s) is the only power source

ON

• the battery or battery charger energizes these buses and components
• switched hot battery bus
• the Standby Power Control Unit (SPCU)
• provides automatic switching of the battery bus, DC standby bus, and AC standby bus (through the inverter) to battery power with loss of normal power
• the battery bus, DC standby bus, static inverter (SPCU closes the RCCB to give power to the inverter), and AC standby bus
• the LED alphanumeric display
• BAT bus can be powered with the BAT switch OFF by moving the standby power switch to BAT

Question 6

CAB/UTIL Power Switch
ON
OFF

Answer 6

ON
-	supplies electrical power to the galley and cabin equipment systems
-	all 115V AC galley busses
-	left and right recirculation fans
-	fwd and aft door area heaters
-	drain mast heaters
-	lavatory water heaters
-	logo lights
-	potable water compressor
-	115V AC shaver outlets if installed
OFF
-	removes electrical power from these components

Question 7

IFE/SEAT PASS Power Switch
ON
OFF

Answer 7

ON
- supplies electrical power to installed components of the passenger seats, in-flight entertainment systems, and other power systems
- 115v ac audio and video entertainment equipment
- cabin telephone equipment
- 28v dc video equipment and passenger seat electronic outlets
OFF
- removes electrical power from these components

Question 8

BAT DISCHARGE light

Answer 8

• excessive battery discharge detected with BAT switch ON
• normal during APU start using ship’s battery
• does not illuminate if using AC power (#1 AC xfr bus is powered)