Electrics 3 - battery / switches / generator

Question 1

Aircraft batteries are made of (3)

Answer 1

Lead-acid
nickel cadmium (NiCd)
Lithium (LiB)

Question 2

Which types of battery are prone to thermal runaway?

Answer 2

nickel cadmium (NiCd)
Lithium (LiB)

Because they have a negative temperature coefficient of resistance

Question 3

Batteries are comprised of cells. How are they wired, and why?

Answer 3

series, to reach the desired output voltage

Question 4

A battery system will either be 12 or 24 vault. What will a battery read when being discharged?
What will the battery read when being charged?

Answer 4

Voltage will drop slightly when under load.
Will require 14v (ish) to charge

Question 5

Battery capacity is measured in what unit?
What can reduce it?

Answer 5

Ampere hours
the cold. (also reduced the rate of discharge

Question 6

Thermal runaway can be caused by (3)

Answer 6

excessive heat (internal or external)
damage / mechanical damage
Excessive battery charge

Question 7

Lithium batteries are not just there to power the aircraft. Where else can they be found?

Answer 7

Passenger devices

Question 8

The only way to extinguish a lithium battery fire is to…

Answer 8

cool it with water or non-flammable liquid

Question 9

What is a bussbar

Answer 9

substantial connector, powered by an electrical source which has attachment points to allow connection of multiple loads.

Question 10

What is nominal voltage, how does changing deviate from this?

Answer 10

Standard voltage, 12v or 24v but there is an operating range around this.
20% more for charging.

Question 11

In a NiCad battery, what electrolyte is used?

Answer 11

The plates are made of Nickel Oxide and Cadmium which are both suspended in a electrolyte solution of potassium hydroxide.

Question 12

Thermal runaway is?

Answer 12

Uncontrolled increase in temperature due to an uncontrolled increase in current.

The battery does not need to be damaged.

Question 13

Thermal runaway can be seen as a cycle of what three things?

Answer 13

Current and temperature rise
resistance drops

Question 14

Material Temperature Characteristics
…..

Answer 14

…..

Question 15

As a rule.
Connecting batteries in series will increase _________
whereas connecting batteries in parallel will increase _________

Answer 15

Series - Increase voltage
Parallel - increase current

Question 16

Permanent magnet holds it’s magnetism. They are based on a core made of ____ ____

Answer 16

hard iron

Question 17

An electro magnet is only magnetised when current is passed through the coil.
What is the material?
What property has to be changed to increase the magnetic strength?

Answer 17

Soft iron
Current

Question 18

Within the generator two components are common to all:

Answer 18

The Armature – the power producing component and where electron flow is created

The Electro-magnet – Provides the magnetic field to create inductance.

Question 19

Alternating current requires which generator?

Answer 19

Alternator

Question 20

Direct current requires which generator?

Answer 20

Dynamo

Question 21

DC Dynamo

Armature (coil) =
Magnets =

Answer 21

Rotor
Stator

Question 22

AC Alternator

Armature (coil) =
Magnets =

Answer 22

Stator
Rotor