737 Electrical

Electrical

B737 NG's metering panel This panel is slightly non-standard because it contains the optional APU BAT position on the DC side. Most classics don't have this second battery.

B737 Classic's metering panel Notice the new CAB/UTIL & IFE/PASS SEAT switches that replace the GALLEY switch in NG. These control the following services: (See the table at right)

The Residual Volts button (not installed on the NG) may be used to test a generator that has dropped off a bus. When pressed, if a voltage is seen then the generator is still turning, therefore a generator showing zero residual volts has failed and will not reconnect. Residual volts is the only selection to use to the 30V scale on the AC voltmeter, for this reason residual volts should never be pressed when a generator is connected to a bus (will get 115V).

Notice the new CAB/UTIL & IFE/PASS SEAT switches that replace the GALLEY switch. These control the following services:

CAB/UTIL IFE/PASS SEAT

Recirculation fan(s) 115V AC audio IFE

Door area heaters 115V AC video IFE

Drain mast heaters 28V DC video IFE

Lavatory water heaters Airphone equipment

All galley buses Pax seat elec outlets

Shaver outlets

Logo lights

Potable water comp

DC voltages are measured at the following points:

DC Selector switch Voltage measurement point Typical Voltage Typical Current STBY PWR DC Standby bus 24-30 N/A BAT BUS Battery bus 24-30 N/A BATT Hot battery bus 22-30* 0 TR1 DC bus 1 24-30 20-25 TR2 DC bus 2 24-30 20-25 TR3 TR 3 24-30 10-15 TEST Power system test module See table See table - May be up to 33V during pulse mode charging.

Do not leave the DC meter selector at BAT on a dead aircraft, because indicating draws some current and will eventually drain the battery.