Boeing B737 MAX - Electrical

Each IDG supplies its own bus system in normal operation and can also supply essential and non-essential loads of the opposite side bus system when one IDG is inoperative.

False.

True.

Correct! Wrong!

During cruise, one engine driven generator drops off-line. Indications that the crew should see include:

A SOURCE OFF light and a GEN OFF BUS light

All statements are correct.

A TRANSFER BUS OFF light and a GEN OFF BUS light

Illumination of the fuel pump, probe heat, respective hydraulic pumps powered by the associated Transfer bus

Correct! Wrong!

AUTOMATIC LOAD SHEDDING (ENGINE GENERATORS) - For single generator operation, the system is designed to shed electrical load incrementally based on actual load sensing. What is the first bus that is shed?

The galleys and main bus on transfer bus 2 are shed first

The galleys and main bus on transfer bus 1 are shed first

The AC standby bus is shed first.

The DC standby bus is shed first.

Correct! Wrong!

Illumination of the blue GEN OFF BUS light indicates:

The IDG is not supplying power to its associated transfer bus

he associated transfer bus is not powered

The generator is not supplying power to its associated generator bus.

The associated generator bus is not powered

Correct! Wrong!

The purpose of the AC ground service bus is to power:

The utility outlets

The cabin lighting

All statements are correct.

The battery charger

Correct! Wrong!

The switched hot battery bus is powered whenever:

The battery switch is ON.

TR1 is powered.

AC ground service bus is powered.

Transfer bus 1 is powered.

Correct! Wrong!

Both AC Transfer busses can be powered simultaneously by:

The APU generator while on the ground or inflight

No single source can power both AC Transfer busses simultaneously

A single IDG on the ground or inflight and the APU generator while on the ground or inflight

A single IDG on the ground or inflight

Correct! Wrong!

The cross bus tie relay:

Opens up if BUS TRANSFER switch is moved to OFF

Will trip off when AC volts reaches 26 volts (plus or minus 4 volts) as displayed on the AC voltmeter

Must be manually opened using the BUS TRANSFER Switch during a Flight Director approach

Normally powers the Battery Charger and backs-up TR units 1 and 2 through a diode

Correct! Wrong!

One basic principle of operation for the B737 electrical system is:

There is no paralleling of the AC power sources.

All generator bus sources can be automatically connected by the Standby Power System.

There is no paralleling of any power source.

An AC power source may be used in parallel with a DC power source.

Correct! Wrong!

With the STANDBY switch in the AUTO position, the loss of all engine or APU electrical power results in the automatic switching from the normal power source to the alternate source for standby power:

Will not occur.

Inflight only.

Either inflight or on the ground.

On the ground only.

Correct! Wrong!

What is the significance of an illuminated ELEC light?

The battery is discharged.

One of the three TRs has failed.

The DC system or standby system equipment has failed.

Two or more TRs have failed.

Correct! Wrong!

DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery and each of the three TRs. The standby power and battery bus displays only DC voltage. Normal indication is:

24 +/- 10 volts.

26 +/- 4 volts.

14 +/- 4 volts.

12 +/- 4 volts.

Correct! Wrong!

During primary charge cycle operation battery voltage can be as high as 30 +/- 3 volts

Which bus supplies electrical power to the auxiliary battery charger?

Transfer bus 1

AC ground service bus 1

Transfer bus 2

AC ground service bus 2

Correct! Wrong!

The TR3 Disconnect Relay:

Automatically opens at glide slope capture during a Flight Director or Autopilot ILS approach

Must be manually opened using the BUS TRANSFER Switch during a Flight Director approach

Will trip off when AC volts reaches 26 volts (+ or - 4 Volts) as dispalyed on the AC Voltmeter.

Normally powers the Battery Charger and backs-up TR units 1 & 2 through a diode

Correct! Wrong!

It is possible to power one transfer bus with external power and the other transfer bus with the APU?

No.

Yes.

Correct! Wrong!

The auxiliary battery operates in parallel with the main battery when the battery is powering the standby bus.

True.

False.

Correct! Wrong!

AUTOMATIC LOAD SHEDDING (ENGINE GENERATORS) - For single generator operation, the system is designed to shed electrical load incrementally based on actual load sensing. When configuration changes to more source capacity (two generator operation), automatic load restoration of the main busses, galley busses and IFE buses occurs. Manual restoration of galley and main bus power can be attempted by:

Moving the CAB/UTIL Power Switch to OFF, then back ON.

Moving the CAB/UTIL Power Switch to OFF for 5 minutes minimum, then back ON.

Moving the CAB/UTIL Power Switch to OFF for 3 minutes minimum, then back ON.

Moving the CAB/UTIL Power Switch to OFF for 2 minutes minimum, then back ON.

Correct! Wrong!

After the loss of all generators, two fully charged batteries have sufficient capacity to provide standby power for a minimum of:Two fully charged batteries have sufficient capacity to provide standby power forrna minimum of

20 minutes

45 minutes

60 minutes

30 minutes

Correct! Wrong!

What is the source of power for TR3?

AC standby bus.

Transfer bus 2.

Transfer bus 1 or 2.

Transfer bus 1.

Correct! Wrong!

For ground service, a ground service switch is available on:

Aft overhead panel on the Flight Deck

The overhead panel in the flight deck.

Aft attendantu00b4s panel

Forward attendantu00b4s panel

Correct! Wrong!

On the ground, with the BATTERY switch OFF and STANDBY POWER Switch in BAT, the switched hot battery bus is:

Not powered

Correct! Wrong!

When the STANDBY POWER Switch is OFF:

The STANDBY PWR OFF light will be extinguished

The STANDBY PWR OFF light will be illuminated

Automatic switching is provided from normal power sources to alternate power sources

The Static Inverter provides 28V DC power to Transfer Bus No.1.

Correct! Wrong!

Both On the ground and in flight a amber ELEC light comes on to indicate that a fault exists in DC power system or standby power system.

True.

False.

Correct! Wrong!

The ELEC light is inhibited in flight.

The purpose of the cross tie relay is to:

Isolate transfer bus 1 and 2

Isolate DC bus 1 from DC bus 2

Disconnect TR1 and TR3

Disconnect TR2 and TR3

Correct! Wrong!

The IDGs contain the generator and drive in a common housing, and are lubricated and cooled by a external oil system attached to the gearbox.

True.

False.

Correct! Wrong!

The IDGs contain the generator and drive in a common housing, and are lubricated and cooled by a self-contained oil system.

The 115V AC Standby Bus is powered by:

The Battery through the Static Inverter with a failure of both engine driven generators.

The 115V Transfer Bus No.1 under normal conditions.

The 115V Transfer Bus No.1 under normal conditions and the Battery through the Static Inverter with a failure of both engine driven generators.

The Battery Bus through the Static Inverter under normal conditions.

Correct! Wrong!

The ELEC light will illuminate in flight if:

The ELEC light only operates on the ground.

A fault exists in the AC or Standby power system.

A fault exists in the AC, DC or the Standby system.

A fault exists in the DC or Standby system.

Correct! Wrong!

The TR UNIT will illuminate in flight if:

TR3 fails.

TR2 fails.

Any TR unit fails.

TR1 fails or TR2 and TR3 fail.

Correct! Wrong!

The TR3 cross bus tie relay automatically opens at glide slope capture to:

Provide more power to DC bus 1.

Ensure that the STANDBY DC is powered.

Provide more power to the AC STANDBY Bus.

Prevent a single bus failure from affecting both navigation receivers and Flight Control Computers (FCCs).

Correct! Wrong!

DC busses powered from the battery following a loss of both generators are:

Battery bus, DC Standby bus, Hot battery bus & Switched hot battery bus (even when the battery switch is OFF).

Battery bus, DC Standby bus, Hot battery bus.

Battery bus, DC Standby bus, Hot battery bus & Switched hot battery bus.

DC standby Bus, Hot Battery Bus & Switched hot battery bus.

Correct! Wrong!

Transformer rectifier (TR) units and the main battery/battery charger supply DC power.

False.

True.

Correct! Wrong!

The Engine Integrated Drive Generators (IDGs):

Allow the generator to maintain a constant speed throughout the normal range of operation

Are used in conjunction with a separate generator drive unit (CSD)

Adjust varying generator speeds to maintain a constant frequency throughout normal range of operation

Operate whenever the engine is operating and cannot be completely isolated from their associated generator.

Correct! Wrong!

The main and auxiliary batteries also provide backup power for the DC standby system only.

True.

False.

Correct! Wrong!

The main and auxiliary batteries also provide backup power for the AC and DC standby system.

Which is the power source for the AC standby bus?

Battery Bus through the Static Inverter under normal conditions

Transfer bus 1 under normal conditions

Transfer bus 2

AC main bus 1

Correct! Wrong!

What is the source of power for TR2?

Transfer bus 1.

Transfer bus 2.

AC Standby bus

Transfer bus 2 or Transfer bus 1.

Correct! Wrong!

Either generator or the APU can power both transfer buses. In the event a power source fails, what is required for that transfer bus to be powered by the opposite transfer bus power source?

The battery switch must be OFF.

The battery switch must be ON.

The BUS TRANS switch must be in the AUTO position.

The generator switch must be OFF.

Correct! Wrong!

The GROUND POWER AVAILABLE light will extinguish when:

The AC ground power cart has been disconnected

The pneumatic ground cart is disconnected

The GROUND POWER switch is positioned ON

The GROUND SERVICE switch is positioned ON

Correct! Wrong!

Galley busses are powered from:

The Battery bus.

The main busses.

The AC Transfer busses.

The generator busses.

Correct! Wrong!

When the aircraft batteries is the only source of power:

The Captain's inboard and outboard displays operate until the battery is discharged and the First Officer's inboard and outboard displays operate for a minimum of 5 minutes

Both the Captain's and First Officer's PFD/ND displays remain operative but only DEU No 1 is powered until the battery is discharged

The Captain's inboard and the First Officer's inboard and outboard displays are inoperative

The Captain's inboard and outboard displays operate until the battery is discharged

Correct! Wrong!

What is the purpose of the GROUND SERVICE switch?

Provide manual control of ground service busses.

Provide manual control of ground service bus.

Provides automatic control of ground service bus.

Provide automatic control of ground service busses.

Correct! Wrong!

Enables servicing airplane using external power without activating AC transfer busses.rn

With external DC power connected to the external DC power receptacle:

The APU can be started using DC external power.

All circuits normally powered by the battery are powered.

There is no external DC power receptacle.rn

The battery is paralleled with the DC External power source.

Correct! Wrong!

In flight if APU is the only source of electrical power:

Only galley bus A & B are automatically shed

All galley busses are automatically shed

Only galley bus C & D are automatically shed

No galley busses are automatically shed

Correct! Wrong!

Illumination of the BAT DISCHARGE light indicates:

The battery bus is not powered.

Excessive battery discharge is detected with the battery switch ON.

The battery is being overcharged.

The DC meter is in the BAT position with the battery switch ON.

Correct! Wrong!

If the AC source powering a transfer bus fails, the transfer bus will remain unpowered.

False.

True

Correct! Wrong!

The main battery charger is powered through:

AC ground service bus 2

AC main bus 1

Transfer Bus 1

DC bus 1

Correct! Wrong!

Illumination of the GEN BUS OFF light indicates:

The associated generator bus is not powered.

The IDG is not supplying power to its associated Transfer bus.

The associated transfer bus is not powered.

The generator is not supplying power to its associated generator bus.

Correct! Wrong!

A high oil temperature in the IDG would cause an automatic disconnect of the IDG.rnrnrn

True.

False.

Correct! Wrong!

DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery and each of the 3 TRs. The Standby power and battery bus displays only Dc voltage. Normal indication is ______ volts

24 +/- 4

26 +/- 6

26 +/-4

24 +/-2

Correct! Wrong!

Because engine generators power the transfer busses directly, and transfer busses are connected by a bus tie system, the loss of an engine driven generator will not necessarily result in the loss of any bus(ses).

True.

False.

Correct! Wrong!

On the ground, with the battery switch OFF and STANBY POWER Switch in AUTO, the Battery Bus is:

Not powered.

Correct! Wrong!

In flight, if the APU is supplying both AC Transfer busses, positioning the BUS TRANS switch to OFF will:

Cause AC Transfer bus No.2 to lose power

Cause AC Transfer bus No.1 to lose power

Not cause either AC Transfer bus to fail.

Cause both AC Transfer busses to lose power

Correct! Wrong!

The illumination of the GND POWER AVAILABLE light indicates:

Ground power is connected however no airplane power quality is measured.

The external power bus is powered by a ground power supply.

Ground power is connected and meets airplane power quality standards.

The Ground Service Bus is powered by a ground power supply.

Correct! Wrong!

Normal AC voltmeter indication for the APU generator with the AC busses loaded:

10 to 135 volts.

100 to 125 volts.

115 to 125 volts.rn

110 to 125 volts.

Correct! Wrong!

Illumination of the STANDBY POWER OFF light indicates:

DC bus 1 unpowered

AC standby bus unpowered

Hot battery bus unpowered

DC bus 2 unpowered

Correct! Wrong!

Boeing 737 MAX - Electrical

Quiz

Boeing B737 MAX - Electrical

Each IDG supplies its own bus system in normal operation and can also supply essential and non-essential loads of the opposite side bus system when one IDG is inoperative.

During cruise, one engine driven generator drops off-line. Indications that the crew should see include:

AUTOMATIC LOAD SHEDDING (ENGINE GENERATORS) - For single generator operation, the system is designed to shed electrical load incrementally based on actual load sensing. What is the first bus that is shed?

Illumination of the blue GEN OFF BUS light indicates:

The purpose of the AC ground service bus is to power:

The switched hot battery bus is powered whenever:

Both AC Transfer busses can be powered simultaneously by:

The cross bus tie relay:

One basic principle of operation for the B737 electrical system is:

With the STANDBY switch in the AUTO position, the loss of all engine or APU electrical power results in the automatic switching from the normal power source to the alternate source for standby power:

What is the significance of an illuminated ELEC light?

DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery and each of the three TRs. The standby power and battery bus displays only DC voltage. Normal indication is:

Which bus supplies electrical power to the auxiliary battery charger?

The TR3 Disconnect Relay:

It is possible to power one transfer bus with external power and the other transfer bus with the APU?

The auxiliary battery operates in parallel with the main battery when the battery is powering the standby bus.

After the loss of all generators, two fully charged batteries have sufficient capacity to provide standby power for a minimum of:Two fully charged batteries have sufficient capacity to provide standby power forrna minimum of

What is the source of power for TR3?

For ground service, a ground service switch is available on:

On the ground, with the BATTERY switch OFF and STANDBY POWER Switch in BAT, the switched hot battery bus is:

When the STANDBY POWER Switch is OFF:

Both On the ground and in flight a amber ELEC light comes on to indicate that a fault exists in DC power system or standby power system.

The purpose of the cross tie relay is to:

The IDGs contain the generator and drive in a common housing, and are lubricated and cooled by a external oil system attached to the gearbox.

The 115V AC Standby Bus is powered by:

The ELEC light will illuminate in flight if:

The TR UNIT will illuminate in flight if:

The TR3 cross bus tie relay automatically opens at glide slope capture to:

DC busses powered from the battery following a loss of both generators are:

Transformer rectifier (TR) units and the main battery/battery charger supply DC power.

The Engine Integrated Drive Generators (IDGs):

The main and auxiliary batteries also provide backup power for the DC standby system only.

Which is the power source for the AC standby bus?

What is the source of power for TR2?

Either generator or the APU can power both transfer buses. In the event a power source fails, what is required for that transfer bus to be powered by the opposite transfer bus power source?

The GROUND POWER AVAILABLE light will extinguish when:

Galley busses are powered from:

When the aircraft batteries is the only source of power:

What is the purpose of the GROUND SERVICE switch?

With external DC power connected to the external DC power receptacle:

In flight if APU is the only source of electrical power:

Illumination of the BAT DISCHARGE light indicates:

If the AC source powering a transfer bus fails, the transfer bus will remain unpowered.

The main battery charger is powered through:

Illumination of the GEN BUS OFF light indicates:

A high oil temperature in the IDG would cause an automatic disconnect of the IDG.rnrnrn

DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery and each of the 3 TRs. The Standby power and battery bus displays only Dc voltage. Normal indication is ______ volts

Because engine generators power the transfer busses directly, and transfer busses are connected by a bus tie system, the loss of an engine driven generator will not necessarily result in the loss of any bus(ses).

On the ground, with the battery switch OFF and STANBY POWER Switch in AUTO, the Battery Bus is:

In flight, if the APU is supplying both AC Transfer busses, positioning the BUS TRANS switch to OFF will:

The illumination of the GND POWER AVAILABLE light indicates:

Normal AC voltmeter indication for the APU generator with the AC busses loaded:

Illumination of the STANDBY POWER OFF light indicates: