Chapter

10

DC Electrics - Specimen Questions

Questions – General 1 . .	. . . . . . . . . . . . . .	. .	. .	. .	. .	.	.	151
Questions – General 2 . .	. . . . . . . . . . . . . .	. .	. .	. .	. .	.	.	154
Answers – General 1 . .	. . . . . . . . . . . . . .	. .	. .	. .	. .	. .		.156
Answers – General 2 . .	. . . . . . . . . . . . . .	. .	. .	. .	. .	. .		.156

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10 Questions

Questions 10

150

Questions 10

Questions – General 1

1.Spare fuses are carried:

a.at the operators’s discretion

b.for generators only

c.by law with a stated minimum number required

d.by the first officer

2.When selecting a fuse for a circuit the governing factor is:

a.the voltage of the circuit

b.the fuse length and diameter

c.the resistance of the circuit

d.the power requirement of the circuit

3.Differential cut-outs close when a differential voltage exists between the:

a.generator bus and battery bus bar

b.generator bus bar and earth

c.batteries

d.battery bus bar and earth

4.Circulating current is the term used to describe:

a.back EMF

b.current necessary to excite the generator

c.current passing between two paralleled generators of differing voltage

d.current passing between AC and DC systems

5.A megohm is:

a.10 000 ohms

b.1000 ohms

c.1 000 000 ohms

d.1 000 000 000 ohms

6.Load shedding is:

a.transferring the loads between generators

b.reducing the load voltage

c.overall reduction of electrical load on the system

d.overall reduction of generator voltages

7.When a generator is on line and its associated ammeter reads 10 amps, this is an indication of:

a.BTBs being energized

b.battery charge rate

c.battery discharge rate

d.generator load

Questions 10

151

10 Questions

8.	The formula for calculating power is:
	a.	V2	or I2 × R or I × V
		R
	b.	V2	or I × R or I × V
		R
	c.	V	or I2 × R or I2 × V
		R2
	d.	V	or I × R2 or I × V
		R2

	9.	Assuming a 5 amp circuit has failed during flight and investigation has shown that
		the fuse is open circuit, the action to be taken is to:
		a.	switch the circuit off immediately
	10	b.	switch off, replace the fuse with another of the correct rating for the circuit
			and repeat this action as often as necessary
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		c.	leave the switch on, replace the failed fuse with one of increased rating
		d.	switch off, replace the failed fuse with one of the correct rating once only
	10.	If the voltage in a circuit is doubled, the current will:
		a.	double
		b.	increase only if the battery is in circuit
		c.	remain the same
		d.	decrease
	11.	A simple electrical circuit has a current flow of 4 amperes and its resistance is 5
		ohms. How much power (watts) is used?
		a.	20 watts
		b.	45 watts
		c.	80 watts
		d.	100 watts
	12.	Check a lead acid battery voltage:
		a.	only if a fault is suspected
		b.	on load with a voltmeter
		c.	on no load with a voltmeter
		d.	on open circuit with a voltmeter
	13.	Connecting two batteries in series will:
		a.	increase the voltage and capacity
		b.	have no effect
		c.	decrease the voltage and the capacity
		d.	increase the voltage, the capacity will remain the same

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			Questions		10
	14.	An aircraft has a battery with a capacity of 60 Ah. Assuming that it will provide its
		nominal capacity and is discharged at the 10 hour rate:
		a.	it will pass 60 amperes for 10 hours
		b.	it will pass 10 amperes for 6 hours
		c.	it will pass 6 amperes for 10 hours
		d.	it will pass 60 amperes for 1 hour
	15.	A NiCad battery shows a high temperature after engine start, this could be an
		indication of:
		a.	thermal runaway
		b.	it is not connected to the battery bus bar
		c.	normal temperature during charging
		d.	depends upon the outside air temperature
	16.	When generators are connected in parallel their output voltage must be:
		a.	divided by the circuit resistance	10
		b.	the same		Questions
		c.	added together
		d.	controlled by one generator

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