DB's SY 737 Electrical

Question 0

TR UNIT light - ON

1. Ground
2. Flight

Answer 0

1. Any TR has failed

2. TR1 OR TR2 and TR3 have failed

Question 1

BAT DISCHARGE light - ON

Answer 1

Excessive battery discharge (with BAT switch on)

Question 2

ELEC light - ON

Answer 2

A fault exists in DC or STBY power system.

Ground only

Question 3

BAT Switch - OFF with normal power sources (with AC power)

Answer 3

Removes power from BAT and Switched Hot Bat buses

Question 4

BAT Switch: OFF when only BAT power (without AC power)

Answer 4

Removes power from:

1. BAT bus
2. Switched Hot Bat bus
3. DC Standby bus
4. Static inverter
5. AC Standby bus

Question 5

BAT Switch - ON

Answer 5

1. Powers Switched Hot Bat bus

2. Energizes relays for automatic switching of STBY system to Bat power with loss of normal power

Question 6

What components are powered by the CAB/UTIL Switch?

Answer 6

1. All 115V AC galley buses
2. Recirc fan(s)
3. Fwd and aft door area heaters
4. Drain mast heaters
5. Lav water heaters
6. Logo lights
7. Potable water compressor
8. 115V AC shaver outlets
9. LED Cabin lighting

Question 7

What components are powered by the IFE/PASS Switch?

Answer 7

1. 115V AC audio entertainment equipment
2. 115V AC video entertainment equipment
3. 28V DC video equipment and passenger seat electronic outlets

Question 8

Generator DRIVE light - ON

Answer 8

IDG low oil pressure caused by:

1. IDG failure
2. Engine shutdown
3. IDG auto disconnect due to high oil temp
4. IDG DISCONNECT Switch

Question 9

When is IDG DISCONNECT switch available?

Answer 9

If electrical power is a available and engine start lever is in IDLE.

Question 10

STANDBY PWR OFF light - ON

Answer 10

One or more buses are unpowered:

1. AC STBY
2. DC STBY
3. Bat bus

Question 11

STANDBY POWER Switch - AUTO with AC transfer buses powered.
What powers:
1. AC STBY bus
2. DC STBY bus

Answer 11

1. AC transfer bus 1

2. TR1, TR2 and TR3

Question 12

STANDBY POWER Switch - AUTO with loss of all AC power. 
What powers:
1. AC STBY bus
2. DC STBY bus
3. Bat bus

Answer 12

1. Bat via static inverter
2. Bat
3. Bat

Question 13

STANDBY POWER Switch - OFF

Answer 13

Removes power from:

1. AC STBY bus
2. Static inverter
3. DC STBY bus

Question 14

STANDBY POWER Switch - BAT

Answer 14

• AC STBY bus powered by Bat via Static inverter

* DC STBY bus and BAT bus powered by Battery.

Question 15

GRD POWER AVAILABLE light - ON

Answer 15

Ground power is connect and meets airplane power quality standards (good freqs and volts)

Question 16

GRD PWR switch - OFF

Answer 16

Disconnects ground power from AC transfer busses

Question 17

GRD PWR switch - ON (with GROUND PWR AVAILABLE light ON)

Answer 17

Removes previous power from AC transfer busses and then connects ground power.

Question 18

TRANSFER BUS OFF Light - ON

Answer 18

Related transfer bus is not powered

Question 19

SOURCE OFF light - ON

Answer 19

1. No source has been manually selected to power transfer bus
   Or
2. The manually selected source has been disconnected

Question 20

GEN OFF BUS light - ON

Answer 20

IDG is not supplying power to related transfer bus

Question 21

GEN switch - OFF

Answer 21

Disconnects IDG from related AC transfer bus (by opening generator CB)

Question 22

GEN switch - ON

Answer 22

Connects IDG to related AC transfer bus (by disconnecting previous source and closing gen CB)

Question 23

BUS TRANSFER Switch - AUTO

Answer 23

1. BTBs operate automatically to maintain power to AC transfer busses
2. DC cross tie relay automatically provides normal or isolated operation as required

Question 24

BUS TRANSFER Switch - OFF

Answer 24

1. Isolates AC transfer bus 1 from AC transfer bus 2 (if one IDG is supplying power to both AC transfer busses) 2. DC cross tie relay opens (to isolate DC bus 1 from DC bus 2)

Question 25

APU GEN OFF BUS light - ON

Answer 25

APU is running and not powering a bus

Question 26

What is the automatic gen online feature?

Answer 26

If the airplane takes off with the APU powering both AC transfer busses and the APU is the shut down or fails, the engine gens are automatically connect to their related busses. (Max once per flight)

Question 27

When will the cross bus tie relay open automatically?

Answer 27

1. At glide slope capture | 2. Bus transfer switch - OFF

Question 28

How long will two fully charged batteries provide STBY power?

Answer 28

60 mins

Question 29

What buses are powered with only Batteries online?

Answer 29

1. Bat 2. DC STBY 3. Hot Bat 4. switched Hot Bat 5. AC STBY (via static inverter)

Question 30

On STBY power only, what flight instruments are powered?

Answer 30

1. CA's inboard and outboard displays 2. Clocks 3. Left EFIS control panel 4. STBY instruments (RMI, airspeed, altimeter, attitude, and mag compass)

Question 31

What does the GROUND SERVICE Switch (Flight Attendant Panel) provide?

Answer 31

Manual control of ground service busses enabling servicing airplane using external power without activating AC transfer busses

Question 32

What are the two basic principles of operation for the 737 electrical system?

Answer 32

1. There is no paralleling of the AC sources of power | 2. The source of power being connected to a transfer bus automatically disconnects an existing source