11.6 Electrical Power MCQ's

Question 1

A lead-acid battery is considered to be fully charged when the.
Option A. cells begin to gas freely.
Option B. SG and voltage remain constant for specified period.
Option C. SG reaches 1.180.

Answer 1

Correct Answer is. SG and voltage remain constant for specified period.

Question 2

The preferred method of battery charging a Ni-Cad battery is constant.
Option A. voltage.
Option B. current.
Option C. power.

Answer 2

Correct Answer is. current.

Question 3

When a current transformer is disconnected, what should be done?.
Option A. Terminals shorted.
Option B. Resistor placed across terminals.
Option C. Left open circuit.

Answer 3

Correct Answer is. Terminals shorted.

Question 4

What does the differential sensing coil sense?.
Option A. Power.
Option B. Volts.
Option C. Current.

Answer 4

Correct Answer is. Current.

Question 5

Where does the GCU gets its power?.
Option A. RAT.
Option B. Battery.
Option C. PMG.

Answer 5

Correct Answer is. PMG.
Explanation. . PMG is main supply for GCU, battery is back up power for GCU.

Question 6

Galley loads are wired in.
Option A. parallel so load shedding will lower current consumption.
Option B. either series or parallel depending on the design.
Option C. series.

Answer 6

Correct Answer is parallel so load shedding will lower current consumption.
Explanation. All loads on an aircraft are wired in parallel.

Question 7

A fuse-type current limiter.
Option A. can be used as a radio suppressor.
Option B. limits current flow to a load.
Option C. opens a circuit after a time/current condition has been exceeded.

Answer 7

Correct Answer is. opens a circuit after a time/current condition has been exceeded.

Question 8

When a load is shed from a busbar, the.
Option A. busbar voltage decreases.
Option B. current consumption from the bar decreases.
Option C. busbar voltage increases.

Answer 8

Correct Answer is. current consumption from the bar decreases.
Explanation. Aircraft Electricity and Electronics, Eismin, Page 241. Load shedding reduces current consumption.

Question 9

In a multi-generator system, the generator which takes more than its reactive power share is protected by.
Option A. over-voltage and under-voltage protection circuits.
Option B. over-current and under-current protection circuits.
Option C. over-excitation and under-excitation protection circuits.

Answer 9

Correct Answer is. over-voltage and under-voltage protection circuits.

Question 10

Sharing of electrical loads by paralleled DC generators is controlled by.
Option A. equalising circuits which control the field excitation of the generators.
Option B. automatic load shedding.
Option C. equalising circuits which control the speed of the generators.

Answer 10

Correct Answer is. equalising circuits which control the field excitation of the generators.
Explanation. Changing the speed would also change the frequency and thus the phase relationship. Generators are always controlled by adjusting the field strength.

Question 11

Excessive commutator sparking can be caused by.
Option A. rotating field diode failure.
Option B. brushes positioned on MNA.
Option C. weak spring tension.

Answer 11

Correct Answer is. weak spring tension.
Explanation. Weak spring tension of the brushes can cause excessive sparking.

Question 12

Before checking the SG of a battery recently removed from an aircraft.
Option A. take the temperature of the electrolyte.
Option B. carry out a capacity test.
Option C. allow to stabilise for one hour.

Answer 12

Correct Answer is. take the temperature of the electrolyte.

Question 13

On an AC external power plug, the interlock circuit is controlled by pins.
Option A. AB.
Option B. CD.
Option C. EF.

Answer 13

Correct Answer is. EF.

Question 14

Over-voltage protection circuits are activated.
Option A. before the over voltage limit is exceeded.
Option B. after a fixed time delay.
Option C. dependent on the magnitude of the overvoltage.

Answer 14

Correct Answer is. dependent on the magnitude of the overvoltage.

Question 15

A diode connected across a coil will.
Option A. suppress arching when relay is opening and closing.
Option B. prevent back EMF and allow faster switching.
Option C. prevent the coil being fitted the wrong way.

Answer 15

Correct Answer is. prevent back EMF and allow faster switching.

Question 16

Differential protection in a generating system.
Option A. detects current difference between source and load.
Option B. detects voltage difference between source and load.
Option C. uses the volts coil to trip the GCR.

Answer 16

Correct Answer is. detects current difference between source and load.

Question 17

Open phase sensing on a current transformer.
Option A. is detected on generator neutral circuit.
Option B. is detected using all phases.
Option C. is detected using any phase.

Answer 17

Correct Answer is. is detected on generator neutral circuit.

Question 18

If the battery is switched off in flight, the.
Option A. captain’s instruments will be powered from the standby bus.
Option B. battery is disconnected from bus.
Option C. generator voltage falls to zero.

Answer 18

Correct Answer is. battery is disconnected from bus.

Question 19

To flash a generator field the.
Option A. generator is on line and producing a voltage less than the flashing voltage.
Option B. generator rotates but is not on line.
Option C. generator must be stationary.

Answer 19

Correct Answer is. generator must be stationary.

Question 20

Voltage is controlled by.
Option A. the constant speed drive.
Option B. the voltage regulator.
Option C. the swashplate.

Answer 20

Correct Answer is. the voltage regulator.

Question 21

The ground interlock pins are numbered.
Option A. A and B.
Option B. C and N.
Option C. E and F.

Answer 21

Correct Answer is. E and F.

Question 22

Distilled water should be added to a ni-cad battery.
Option A. only in the battery workshop.
Option B. at any time.
Option C. when fully charged.

Answer 22

Correct Answer is. only in the battery workshop.

Question 23

Overflowing electrolyte in a ni-cad battery indicates.
Option A. not enough charging current.
Option B. excessive charging current.
Option C. low electrolyte temperature.

Answer 23

Correct Answer is. excessive charging current.

Question 24

During a normal engine shutdown, generator tripping is initiated by.
Option A. undervoltage.
Option B. underfrequency.
Option C. overcurrent.

Answer 24

Correct Answer is. undervoltage.

Question 25

What would you use to neutralise nicad battery spillage?.
Option A. Boric acid.
Option B. Distilled water.
Option C. Bicarbonate of soda.

Answer 25

Correct Answer is. Boric acid.

Question 26

Before operating generators in parallel, their voltages should be matched to prevent.
Option A. large circulating currents developing.
Option B. overloading the generator drive and shearing of splines.
Option C. voltage spikes of sufficient magnitude to trigger GCU overvoltage circuits.

Answer 26

Correct Answer is. overloading the generator drive and shearing of splines.

Question 27

Consumer loads are connected to a busbar.
Option A. in series so when loads are shed voltage is reduced.
Option B. in parallel so when loads are shed current is reduced.
Option C. in series so when loads are shed current is reduced.

Answer 27

Correct Answer is. in parallel so when loads are shed current is reduced.
Explanation. All loads are connected in parallel with each other.

Question 28

A current transformer connected on the neutral star point of a generator is for.
Option A. overload protection.
Option B. differential current protection.
Option C. negative sequence protection.

Answer 28

Correct Answer is. differential current protection.

Question 29

Differential protection as applied to AC generation systems compares.
Option A. generator current to busbar current.
Option B. generator voltage to busbar voltage.
Option C. ambient pressure to cabin pressure.

Answer 29

Correct Answer is. generator current to busbar current.

Question 30

In an AC generation system, the frequency and phase rotation.
Option A. must be synchronised prior to paralleling.
Option B. is of no consequence after paralleling.
Option C. must be out of phase prior to paralleling.

Answer 30

Correct Answer is. must be synchronised prior to paralleling.

Question 31

Diodes are placed across a contactor to.
Option A. ensure smooth contactor operation.
Option B. prevent contact bounce.
Option C. speed up operation by reducing back EMF.

Answer 31

Correct Answer is. speed up operation by reducing back EMF.

Question 32

Placing the battery master switch to off during flight will.
Option A. isolate the battery from the main busbar.
Option B. shut down the APU.
Option C. disconnect all power to the main busbar.

Answer 32

Correct Answer is. isolate the battery from the main busbar.
Explanation. The Battery master switch simply connects the battery to the main busbar, allowing it to be charged from the generator(s)

Question 33

Whilst operating paralleled AC constant frequency generators, it is important to maintain generator outputs at the same voltage.
Option A. to prevent a circulating current of considerable magnitude developing between two or more generators.
Option B. to prevent CSD shock loading.
Option C. to prevent a circulating current developing between two or more TRUs.

Answer 33

Correct Answer is. to prevent a circulating current of considerable magnitude developing between two or more generators.

Question 34

A voltage regulator installed in series with a generator field.
Option A. uses a voltage coil in series with generator output.
Option B. uses a voltage coil in parallel with generator output.
Option C. uses a current coil in parallel with generator output.

Answer 34

Correct Answer is. uses a voltage coil in parallel with generator output.

Question 35

CSD warning lights on the flight deck normally indicate.
Option A. high oil pressure, low oil temperaturelow oil pressure, high oil temperature.
Option B. low oil pressure, low oil temperature.
Option C. low oil pressure, high oil temperature.

Answer 35

Correct Answer is. low oil pressure, high oil temperature.

Question 36

The output frequency of a hydraulically driven standby generator is controlled by.
Option A. an hydraulically actuated swash plate.
Option B. a CSD.
Option C. an IDG.

Answer 36

Correct Answer is. an hydraulically actuated swash plate.

Question 37

An AC generator used with a CSD.
Option A. needs a voltage controller to maintain voltage with increasing load.
Option B. does not need a voltage controller because current is kept constant.
Option C. does not need a voltage controller because voltage is kept constant.

Answer 37

Correct Answer is. needs a voltage controller to maintain voltage with increasing load.

Question 38

Power to a GCU is supplied.
Option A. initially by a ‘field tickling’ supply and then PMG output.
Option B. by the battery bus or rectified generator output.
Option C. by the generator output only.

Answer 38

Correct Answer is. initially by a ‘field tickling’ supply and then PMG output.
Explanation. PMG is main supply for GCU, battery is back up power for GCU.

Question 39

Trip signals for a GCR are.
Option A. overfrequency and undervoltage.
Option B. differential protection and undervoltage.
Option C. underfrequency and overcurrent.

Answer 39

Correct Answer is. differential protection and undervoltage.

Question 40

Abnormal CSD operation is monitored on the flight deck by observing indications of.
Option A. low oil quantity / low oil temperature.
Option B. high oil temperature / low oil pressure.
Option C. High oil temperature / low oil quantity.

Answer 40

Correct Answer is. high oil temperature / low oil pressure.

Question 41

Wires in hot temperature areas should be bound with.
Option A. Teflon.
Option B. Nomex.
Option C. PVC.

Answer 41

Correct Answer is. Teflon. (PTFE)

Question 42

A heat gun should be operated at.
Option A. 100°C above the specified.
Option B. 100°C below the specified.
Option C. the specified temperature.

Answer 42

Correct Answer is. the specified temperature.
Explanation. A heat gun should be operated at the specified temperature, or 100°C (approx) above the heatshrink temperature.

Question 43

High voltages on a generator in a parallel system should be prevented because.
Option A. it will trip the GCR.
Option B. it will damage the drive shaft.
Option C. it will cause high circulating current in the bus / other generators.

Answer 43

Correct Answer is. it will trip the GCR.

Question 44

Over-voltage condition trips the generator. The time taken to trip the GCU depends on.
Option A. amplitude of voltage.
Option B. closing of fuel and hydraulic valves.
Option C. time delay circuit.

Answer 44

Correct Answer is. amplitude of voltage.
Explanation. Inverse time delay - c could also be considered correct.

Question 45

Speed of an HMG is controlled by a.
Option A. CSD unit.
Option B. swashplate.
Option C. ID unit.

Answer 45

Correct Answer is. swashplate.
Explanation. Speed of an HMG is controlled by a swashplate.

Question 46

A permanent magnet should have.
Option A. low retentivity, low coercivity.
Option B. high retentivity, low coercivity.
Option C. low retentivity, high coercivity.

Answer 46

Correct Answer is. high retentivity, low coercivity.

Question 47

What will happen if the aircraft battery becomes overheated?.
Option A. The power supply to the battery charger will be interrupted.
Option B. The battery charger will switch to trickle charge mode.
Option C. The hot battery bus will be disconnected from the battery.

Answer 47

Correct Answer is. The battery charger will switch to trickle charge mode.
Explanation. B737 switches to trickle charge. However, see Pallett Aircraft Electrical Systems 3rd Edition Figure 1.32 for charger disconnect system.

Question 48

When the temperature increases in a lead acid battery, the SG will.
Option A. decrease.
Option B. increase.
Option C. remain the same.

Answer 48

Correct Answer is. decrease.
Explanation. Since volume increases, but mass remains constant, with temperature, density decreases.

Question 49

On testing a generator it is found to require adjusting, where would you adjust it?.
Option A. In the cockpit on the flight engineers panel.
Option B. On the GCU.
Option C. By means of a remote trimmer.

Answer 49

Correct Answer is. By means of a remote trimmer.
Explanation. Adjusted with a remote trimmer.

Question 50

Control of hydraulically powered emergency electrical generator frequency is.
Option A. by CSU.
Option B. by angle of swash plate.
Option C. by IDG.

Answer 50

Correct Answer is. by angle of swash plate.
Explanation. Control of an HPG is via a swashplate.

Question 51

When a ni-cad battery is fully charged.
Option A. the electrolyte level is higher level than normal.
Option B. the electrolyte level is lower than normal.
Option C. the electrolyte level stays the same.

Answer 51

Correct Answer is. the electrolyte level is higher level than normal.

Question 52

Electrical load on aircraft is controlled by.
Option A. a BPCU.
Option B. an IRS.
Option C. a GCU.

Answer 52

Correct Answer is. a BPCU.
Explanation. ‘The BPCU shares status information with the GCU’s. The BPCU controls all electrical buses and controls load shedding.’.

Question 53

A 4:1 step-up transformer receives 120VAC in its primary and has 1600 Ohms resistance in its secondary. What is the current drawn from the source?.
Option A. 1.2 A.
Option B. 0.3 A.
Option C. 3 A.

Answer 53

Correct Answer is. 1.2 A.
Explanation. Find current in secondary I = V/R = 480/1600 = 3/10A. Next find current in Primary = 4 x 3/10 = 12/10 = 1.2A.

Question 54

After engine start using a Ni-Cad battery, the pilot observes on the battery charger indicator, an initial high current draw followed by a rapid decrease in current.
Option A. there is a problem with the charging circuit and he must shut-down the engines.
Option B. the battery is faulty.
Option C. no cause for concern.

Answer 54

Correct Answer is. no cause for concern.

Question 55

Topping up a Ni-Cad battery in situ.
Option A. is not allowed.
Option B. is only allowed in the shop.
Option C. is permitted.

Answer 55

Correct Answer is. is not allowed.

Question 56

In a lead-acid battery after numerous checks, one cell has low reading.
Option A. It needs topping up.
Option B. It must be replaced.
Option C. It is defective.

Answer 56

Correct Answer is. It must be replaced.

Question 57

A short range passenger aircraft has complete electrical failure. What time duration would the battery be expected to power essential equipment?.
Option A. 30 minutes.
Option B. Forever.
Option C. 60 minutes.

Answer 57

Correct Answer is. 30 minutes.

Question 58

An external power plug has two short pins. These are used for.
Option A. ground handling bus.
Option B. the interlock circuit.
Option C. a guide for correct alignment of the plug in the socket.

Answer 58

Correct Answer is. the interlock circuit.

Question 59

The purpose of a synchronising bus bar is.
Option A. to allow monitoring and trimming from the flight deck.
Option B. to enable two propeller systems to be synchronised.
Option C. to monitor total current load.

Answer 59

Correct Answer is. to allow monitoring and trimming from the flight deck.

Question 60

To confirm the state of charge of a ni-cad battery.
Option A. measure the discharge time.
Option B. subject the battery to load, check voltage and check the SG of each cell.
Option C. subject the battery to load and check the voltage.

Answer 60

Correct Answer is. measure the discharge time.

Question 61

Circulating currents are associated with.
Option A. AC and DC generators in parallel.
Option B. AC generators in parallel.
Option C. DC generators in parallel.

Answer 61

Correct Answer is. AC generators in parallel.

Question 62

Generator brush bedding.
Option A. should only be done if 50% of the width and 80% of the length is already being done.
Option B. should not be done on the aircraft.
Option C. can be done on the aircraft.

Answer 62

Correct Answer is. can be done on the aircraft.

Question 63

What is the amperage at point ‘’ to the nearest amp?.

Option A. 100 Amps.
Option B. 101 Amps.
Option C. 102 Amps.

Answer 63

Correct Answer is. 101 Amps.
Explanation. 100 volts accross far right load, therefore 100 volts also accross 100ohm load (parallel circuit theory) I = V/R = 100/100 = 1A through 100 ohm load. (Ohms Law) Total current at ‘’ is 100 + 1 = 101 Amps. (Kirkchoff’s Law).

Question 64

Pitot tubes are heated by.
Option A. DC.
Option B. AC.
Option C. AC or DC.

Answer 64

Correct Answer is. AC or DC.

Question 65

Paralleling is used for.
Option A. AC and DC electrical generators.
Option B. DC electrical generators only.
Option C. AC electrical generators only.

Answer 65

Correct Answer is. AC and DC electrical generators.

Question 66

Battery charging procedures can be found in ATA.
Option A. Chapter 24 Section 21.
Option B. Chapter 24 Section 31.
Option C. Chapter 31 Section 21.

Answer 66

Correct Answer is. Chapter 24 Section 31.

Question 67

In a carbon pile regulator, the resistive element is.
Option A. in series with the field and changes resistance with surface area contact.
Option B. in parallel with the field and changes resistance with changing length.
Option C. in series with the field and changes resistance with changing length.

Answer 67

Correct Answer is. in series with the field and changes resistance with surface area contact.

Question 68

Maximum battery temperature on charging before protection circuit starts is.
Option A. 144 degrees C.
Option B. 144 degrees F.
Option C. 71 degrees F.

Answer 68

Correct Answer is. 144 degrees F.

Question 69

If an aircraft has no battery charger, the battery is charged by. Option A. constant current until a predetermined limit when it automatically switches to constant voltage.
Option B. constant current.
Option C. constant voltage.

Answer 69

Correct Answer is. constant voltage.

Question 70

The output of a carbon pile regulator with no variation of loading is.
Option A. stationary.
Option B. pulse width modulating.
Option C. fluctuating.

Answer 70

Correct Answer is. stationary.

Question 71

In a transistor voltage regulator, the voltage output is controlled by. Option A. zeners and transistors.
Option B. diodes and transformers.
Option C. transformers and transistors.

Answer 71

Correct Answer is. zeners and transistors.

Question 72

A paralleled relay for a DC system is energised and connected by. Option A. voltage coil.
Option B. current coil.
Option C. voltage and current coil.

Answer 72

Correct Answer is. voltage and current coil.

Question 73

Increasing the real load primarily.
Option A. increases output voltage and increases frequency.
Option B. decreases output voltage.
Option C. decreases frequency.

Answer 73

Correct Answer is. decreases frequency.

Question 74

Inductive reactive load causes.
Option A. no effect on torque but produces extra heat dissipated.
Option B. increase in torque only.
Option C. increase in torque and increase in heat dissipated.

Answer 74

Correct Answer is. no effect on torque but produces extra heat dissipated.

Question 75

The power factor of an AC generator identifies the proportion of.
Option A. apparent power from the generator that does work.
Option B. real power from the generator that does work.
Option C. reactive power from the generator that does work.

Answer 75

Correct Answer is. real power from the generator that does work.

Question 76

Differential protection in an AC system protects against.
Option A. line-line, line-line-line, line-earth faults.
Option B. short circuits.
Option C. a reverse current flowing from the battery.

Answer 76

Correct Answer is. short circuits.

Question 77

When resetting the CSD on the ground, the engine should be.
Option A. rotating at Nsync.
Option B. rotating at idle.
Option C. stationary.

Answer 77

Correct Answer is. stationary.

Question 78

One of the main purposes of a CSD is to.
Option A. prevent engine overload.
Option B. enable generators to be paralleled.
Option C. maintain constant load on the generator.

Answer 78

Correct Answer is. enable generators to be paralleled

Question 79

In an undervolt condition in an AC generator system, the most likely consequence is.
Option A. activation of the time delay circuit.
Option B. energise the bus tie relay.
Option C. deactivation of the field regulatory TRs.

Answer 79

Correct Answer is. activation of the time delay circuit.

Question 80

If voltage and frequency of the generator drop to zero in flight, it would be an indication that the.
Option A. bus tie interlock is inoperative.
Option B. CSD driveshaft had sheared.
Option C. phase sequence detection circuit has operated.

Answer 80

Correct Answer is. CSD driveshaft had sheared.

Question 81

Assuming all systems are operating normally, as aircraft electrical load increases, generator output voltage will.
Option A. increases and amperage output increases.
Option B. remain constant and amperage output increases.
Option C. decrease and amperage output increases.

Answer 81

Correct Answer is. remain constant and amperage output increases.

Question 82

When installing multiple batteries on aircraft, they are connected in.
Option A. series.
Option B. either parallel or series and switched between as an option.
Option C. parallel.

Answer 82

Correct Answer is. either parallel or series and switched between as an option.

Question 83

What is the small pin on the DC ground power connector?.
Option A. Positive to external power relay.
Option B. Positive to battery relay.
Option C. Ground or earth.

Answer 83

Correct Answer is. Positive to external power relay.

Question 84

How is RAT driven?.
Option A. Airstream.
Option B. Compressor.
Option C. Fan.

Answer 84

Correct Answer is. Airstream.

Question 85

How is an aircraft battery rated?.
Option A. Ampere hours.
Option B. Joules.
Option C. Watts.

Answer 85

Correct Answer is. Ampere hours.

Question 86

A reduction in field strength of a DC shunt motor driving a constant load will result in.
Option A. reduced torque and increased speed.
Option B. increased torque and speed.
Option C. increased torque and reduced speed.

Answer 86

Correct Answer is. increased torque and speed.

Question 87

What are the 2 short prongs on an AC plug for?.
Option A. Using AC current to pull on interlock circuit.
Option B. To prevent arcing during plug connection / disconnection.
Option C. To help plug location/fit.

Answer 87

Correct Answer is. To prevent arcing during plug connection / disconnection.
Explanation. The short prongs are for DC only.

Question 88

A vibration contact voltage regulator consists of a shunt winding and a.
Option A. current regulation coil in series.
Option B. voltage regulating coil in series.
Option C. voltage regulating coil in parallel.

Answer 88

Correct Answer is. current regulation coil in series.

Question 89

What is the purpose of diode in a power GCR?.
Option A. To allow flow in the event of failure of the relay.
Option B. To speed up the operation.
Option C. To prevent back-flow of current in the EMF coil.

Answer 89

Correct Answer is. To prevent back-flow of current in the EMF coil.
Explanation. The diode is to prevent the high current flow in the coil due to induction as the relay switches off.

Question 90

Eddy currents are.
Option A. circulating currents.
Option B. caused by heating effect of the coil.
Option C. caused by resistance of the coil.

Answer 90

Correct Answer is. circulating currents.

Question 91

The small pins in the power connector plug are.
Option A. negative.
Option B. neutral.
Option C. positive.

Answer 91

Correct Answer is. positive.

Question 92

When an overvolt is present on an AC generator system, the tripping circuit.
Option A. trips after a time delay inversely proportional to overvolt amplitude.
Option B. trips after a time delay.
Option C. trips at a set level.

Answer 92

Correct Answer is. trips after a time delay inversely proportional to overvolt amplitude.

Question 93

In an AC distribution system, the purpose of the synchronising bus-bar is to.
Option A. provide a means of monitoring the load.
Option B. provide interconnection between the generator load busbars.
Option C. supply essential services.

Answer 93

Correct Answer is. provide interconnection between the generator load busbars.

Question 94

Vibrating contact voltage regulator sensing coil is.
Option A. across the generator output.
Option B. in series with the field windings.
Option C. in parallel with the field windings.

Answer 94

Correct Answer is. in parallel with the field windings.

Question 95

A current transformer connected across the neutral of a 3 phase generator is for.
Option A. load monitoring.
Option B. phase sequence monitoring.
Option C. differential protection.

Answer 95

Correct Answer is. differential protection.

Question 96

Zener diodes are for.
Option A. voltage stabilisation.
Option B. voltage regulation.
Option C. rectification.

Answer 96

Correct Answer is. voltage regulation.
Explanation. An old Module 4 question. Although Zener diodes can be used (back-to-back) to protect equipment from voltage spikes (voltage stabilisation) they are more commonly associated with voltage regulation.

Question 97

AC generator output indications are measured in.
Option A. KVA & KW.
Option B. KW & KVAR.
Option C. KW.

Answer 97

Correct Answer is. KVA & KW.
Explanation. An AC generator is rated in KVA and KW (or KVA and power factor, from which KW can be calculated). However, a DC generator is rated in KW only.

Question 98

Load shedding allows.
Option A. less current to the busbar.
Option B. more current to the busbar.
Option C. more voltage to the busbar.

Answer 98

Correct Answer is. less current to the busbar.
Explanation. Load shedding is carried out to reduce current (voltage is constant).

Question 99

How may the output of a transistorised voltage regulator be described?.
Option A. Variable AC.
Option B. Pulse width modulated DC.
Option C. Slightly variable DC.

Answer 99

Correct Answer is. Pulse width modulated DC.
Explanation. A voltage regulator has two outputs, one to the generator field (pulse width modulated on a transistorised regulator) and one to the busbar (constant voltage but variable current depending on load). The answer here depends upon which output they are referring.

Question 100

In the event of complete AC generator failure in an AC split bus-bar generation system, how is power maintained to the essential AC bus-bar?.
Option A. By power fed from a battery supplied static inverter.
Option B. By power fed from a hot battery bus-bar only.
Option C. By power fed from static inverter only.

Answer 100

Correct Answer is. By power fed from a battery supplied static inverter.

Question 101

In what units are static inverters rated?.
Option A. kVA.
Option B. kVAR.
Option C. kW.

Answer 101

Correct Answer is. kVA.
Explanation. VA or KVA, just like an AC generator.

Question 102

In a generator system, a stability winding is used.
Option A. in series with the field to prevent oscillations.
Option B. to control output current.
Option C. to prevent voltage overshoot.

Answer 102

Correct Answer is. to prevent voltage overshoot.

Question 103

On engine shutdown, what prevents GCR being tripped?.
Option A. Under-volt.
Option B. Under-frequency.
Option C. Under-current.

Answer 103

Correct Answer is. Under-frequency.

Question 104

How is real and reactive load sharing achieved in an AC parallel generator system?.
Option A. Real load by control of the constant speed drives, reactive load by adjustment of generator fields.
Option B. Real and reactive loads by control of the constant speed drives only. Output voltage is controlled by adjustment of generator fields.
Option C. Real load by control of generator fields, Reactive loads by adjustment of the constant speed drives.

Answer 104

Correct Answer is. Real load by control of the constant speed drives, reactive load by adjustment of generator fields.

Question 105

Other than when there is a fault in an aircraft battery or its charging system, when is the charger switched off automatically?.
Option A. When the battery is used for excessively high discharge currents such as in starting.
Option B. When the alternators are fully loaded.
Option C. When there is a failure of one alternator in a split-bus bar system.

Answer 105

Correct Answer is. When the battery is used for excessively high discharge currents such as in starting.

Question 106

The trimmer resister in a carbon pile volts regulator is.
Option A. in series with the generator field.
Option B. in series with the generator volts coil.
Option C. in parallel with the generator volts coil.

Answer 106

Correct Answer is. in series with the generator volts coil.

Question 107

When a field relay trips the generator off-line, it can be reset.
Option A. after the fault has been cleared.
Option B. by cycling the generator switch.
Option C. on the ground only.

Answer 107

Correct Answer is. on the ground only.

Question 108

In a paralleled AC generator system both A phases must be in synchronisation and.
Option A. CBA must equal ABC.
Option B. phase rotation does not matter.
Option C. CBA must equal CBA.

Answer 108

Correct Answer is. CBA must equal CBA.

Question 109

When loads are shed from a busbar automatically.
Option A. bus bar current decreases.
Option B. bus bar current rises.
Option C. bus bar voltage rises.

Answer 109

Correct Answer is. bus bar current decreases.

Question 110

Question Number. 113. What controls output from the generator?.
Option A. BPCU.
Option B. GCU.
Option C. ELCU.

Answer 110

Correct Answer is. GCU.

Question 111

Specific Gravity in a lead acid battery should give an indication of.
Option A. charge.
Option B. electrolyte temperature.
Option C. electrolyte level.

Answer 111

Correct Answer is. charge.

Question 112

During normal engine shut-down, the generator.
Option A. breaker and control relay are both tripped.
Option B. breaker is tripped only.
Option C. control relay is tripped only.

Answer 112

Correct Answer is. breaker is tripped only.

Question 113

The generator warning light will come on when.
Option A. voltage is too high.
Option B. voltage is above battery voltage.
Option C. voltage is below battery voltage.

Answer 113

Correct Answer is. voltage is below battery voltage.

Question 114

When replacing a current transformer.
Option A. it can be fitted any way round.
Option B. voltage/current selection must be made prior to fitting.
Option C. it can only be fitted one way round.

Answer 114

Correct Answer is. it can only be fitted one way round.

Question 115

The economy coil on a relay.
Option A. reduces current required to hold closed.
Option B. makes it cheaper to make.
Option C. reduces current required to close.

Answer 115

Correct Answer is. reduces current required to hold closed.

Question 116

What is the function of the generator control relay?.
Option A. Bring the generator on-line.
Option B. Connect the generator to the busbar.
Option C. Control output voltage.

Answer 116

Correct Answer is. Bring the generator on-line.

Question 117

The current consumed by a DC starter motor will.
Option A. remain constant.
Option B. increase as the engine speed increases.
Option C. decrease as the engine speed increases.

Answer 117

Correct Answer is. decrease as the engine speed increases.
Explanation. Decreases due to the back EMF as engine speed increases.

Question 118

A neutralising agent for sulphuric acid is.
Option A. borax powder.
Option B. citric acid.
Option C. sodium bicarbonate.

Answer 118

Correct Answer is. sodium bicarbonate.

Question 119

In a split bus power distribution system.
Option A. each generator supplies its own bus and distribution system in normal operation.
Option B. generators are paralleled on connection to the tie bus.
Option C. power is split between 115V AC and 28V DC.

Answer 119

Correct Answer is. each generator supplies its own bus and distribution system in normal operation.

Question 120

Flashing a generator field.
Option A. decreases resistance.
Option B. restores magnetism.
Option C. increases resistance.

Answer 120

Correct Answer is. restores magnetism.

Question 121

When checking SG of electrolyte of lead acid battery, what should be taken into account?.
Option A. Electrolyte temperature.
Option B. Battery charge.
Option C. Ambient temperature.

Answer 121

Correct Answer is. Electrolyte temperature.

Question 122

How do you check condition of Ni-Cad battery in situ?.
Option A. By voltmeter connected to the battery terminal.
Option B. By voltmeter in the cockpit when battery is off load.
Option C. By voltmeter in the cockpit, when battery is on load.

Answer 122

Correct Answer is. By voltmeter in the cockpit, when battery is on load.

Question 123

The reactive load circuit in a multi-engined AC generator system.
Option A. modifies generator field excitation current.
Option B. modifies generator drive speed.
Option C. modifies generator field excitation voltage.

Answer 123

Correct Answer is. modifies generator field excitation current.

Question 124

A vibrating type voltage regulator uses a volts coil.
Option A. in series with the generator output.
Option B. in series with the current coil.
Option C. in parallel with the generator output.

Answer 124

Correct Answer is. in parallel with the generator output.

Question 125

The purpose of the economy contacts in a relay is to.
Option A. prevent contact pitting and burning.
Option B. reduce the current required to hold the contacts closed.
Option C. close the auxiliary contacts before the main contacts.

Answer 125

Correct Answer is. reduce the current required to hold the contacts closed.

Question 126

A vibrating contact voltage regulator has.
Option A. a resistor in series with the points.
Option B. a volts coil in parallel with the points.
Option C. a resister in parallel with the points.

Answer 126

Correct Answer is. a resister in parallel with the points.

Question 127

Brush bedding-in on a starter generator can be carried out.
Option A. when 80 percent of the brush area has been previously bedded in, on the bench.
Option B. only off the aircraft.
Option C. during flight.

Answer 127

Correct Answer is. only off the aircraft.

Question 128

What would be the cause of a low electrolyte level in a nicad battery?.
Option A. Evaporation.
Option B. Over charging current.
Option C. Undercharging current.

Answer 128

Correct Answer is. Over charging current.

Question 129

An AC generator connected to a CSD requires.
Option A. a separate voltage regulator.
Option B. no voltage regulator as the CSD will control generator frequency.
Option C. no voltage regulator as the CSD will control the voltage.

Answer 129

Correct Answer is. a separate voltage regulator.

Question 130

Question Number. 133. If electrolyte from a lead-acid battery is spilled in the battery compartment, which procedure should be followed?.
Option A. Apply sodium bicarbonate solution to the affected are followed by a water rinse.
Option B. Apply boric acid solution to the affected area followed by a water rinse.
Option C. Rinse the affected area thoroughly with clean water.

Answer 130

Correct Answer is. Apply sodium bicarbonate solution to the affected are followed by a water rinse.