L-1011 Trainer Installation: AC an DC Standby Power from Battery

L-1011 Trainer: AC and DC STBY Power from Battery

Finished the L-1011 AC Standby (STBY) and DC STBY power fail-over to the on-board Battery yesterday evening. On the actual aircraft, once transferred to Battery power, the standby buses are alive for about 30 minutes before the Battery is depleted.

Normally, the DC STBY bus receives powered from the DC Essential bus and the AC STBY bus is powered by the AC Essential bus. The AC and DC STBY bus are the last resort to keep the aircraft operational in case of a complete loss of primary electrical systems. If the respective Essential power busses fail, the STBY busses are switched to the on-board Battery. AC power is created form the on-board Battery via a DC to 115V/400Hz Inverter. Watch the short demonstration video below and you will see the system in action.

L-1011 Electrical System: Power Bus Distribution

Today Ian Grant asked me to see if I had information on which instrument or system would connect to which power bus in the L-1011. Here is the information for you Ian:

Loosing power in the L-1011 would not be an easy thing. All of the essential instruments can be powered form any bus including a number of standby busses. All in all, the following power busses are available:

1. AC Bus No.1 and Ground Service Bus
2. AC Bus No.2 and Radio Bus No.2
3. AC Bus No.3
4. Essential AC Bus and Essential Radio Bus
5. DC Bus No.1 and Ground Service Bus
6. DC Bus No.2 and Radio Bus No.2
7. DC Bus No.3
8. Essential Dc Bus and Essential DC Radio Bus
9. DC Standby Bus
10. AC Standby Bus
11. Battery Essential Communications and APU Battery Bus
12. Galley and Passenger Service Busses

All in all the L-1011 had a very sophisticated and fault tolerant power distribution system. However, you had an interest in which instrument is connect to which bus as its primary source of power. Below is a series of pictures that will give the exact data:

AC Bus No. 1 and Ground Service Bus

AC Bus No.2 and Radio Bus No.2

AC Bus No.3

Essential AC Bus and Essential Radio Bus

DC Bus No.1 and Ground Service Bus

DC Bus No.2 and Radio Bus No.2

DC Bus No.3

Essential DC Bus and Essential DC Radio Bus

DC Standby Bus

AC Standby Bus

Battery, Essential Communications and APU Battery Bus

Hope this helps. There is a lot more to the power distribution in the L-1011, however, I think this is a good start.

Original Flight Hardware: Interior Lights and Standby Power

The Interior Lights and Standby Power panel is a combination panel found on the forward overhead panel on the First Officer side of the Lockheed L-1011. The left hand side of the panel has the Standby Power switch and the UNARM Indicator light. The right hand side has light switches for the Magnetic Compass and the Eyebrow Panel light switch. The for square switches in the Interior Light panel are use for: No Smoking Sign Switch, Fasten Seat Belt Sign Switch, Eye Locator Light Switch and the Thunderstorm Light Switch.



Here is a more detailed description of the four square switches which all illuminate with "ON" when active. The descriptions are taken from a Lockheed L-1011 Eastern Airlines flight manual from 1973:

NO SMOKING SIGN

IN - ON is illuminated, single chime sounds, cabin NO SMOKING signs and cabin door EXIT signs are illuminated.
OUT - ON is extinguished, single chime sounds, cabin NO SMOKING signs and door EXIT signs are extinguished.

FASTEN SEAT BELT SIGN

IN - ON is illuminated, single chime sounds and cabin FAST SEAT BELT and lavatory RETURN TO SEAT signs are illuminated.
OUT - ON is extinguished, single chime sounds and cabin and lavatory sign lights are extinguished.

THUNDERSTORM LIGHT

IN - ON is illuminated, and all dimmable flight station lights are energized to maximum brilliance regardless of dimming control position.
OUT - ON is extinguished and all flight station lights are controlled by respective dimming control.

EYE LOCATOR

IN - ON is illuminated and pilots' eye position locator is energized.
OUT - ON is extinguished and pilots' eye position locator is de-energized



The Standby Power switch has three positions:

ON .. Manually connects DC Standby bus to the Battery bus which then powers the AC buses via the inverter.
ARM .. Permits automatic transfer to the DC Standby bus if the Essential AC bus fails.
OFF .. Disarms the AC Standby bus system only ... not the DC system.

The UNARM indicator light illuminates when the Standby Power switch is in the OFF position.



Panel Location