Download Electrical-Systems

Aircraft
Electrical
Systems
Ted
Spitzmiller
Aircraft Electrical Systems
1
C-182T Electrical System
Aircraft Electrical Systems
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What is Electricity?
• Flow of electrons from one atom to another
-
+
Aircraft Electrical Systems
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Like a bucket brigade
Aircraft Electrical Systems
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Where do we get ‘positive 'attraction—
from a battery…
Aircraft Electrical Systems
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Putting some ‘resistance’ into the flow
provides useful ‘work’
Aircraft Electrical Systems
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‘Current’ flows in the opposite
direction to the electrons
E
• Current (I) is the ‘amount’
of electrons flowing
• Measured in Amps
• Voltage (E) is the
‘pressure’ of the electrons
• Measured in Volts
Aircraft Electrical Systems
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Moving a coil in a magnet generates
electricity to recharge the battery
Aircraft Electrical Systems
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Two types of ‘current’
Aircraft Electrical Systems
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Aircraft Electrical Systems
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Why is Electricity Dangerous
• Minimum current a human can feel depends on
current type (AC or DC) and freq.
– 1 mA of AC at 60 Hz (1/1000 of an amp)
– 5 mA for DC.
• High current can cause tissue damage or fibrillation
(cardiac arrest)
– 60 mA of AC (rms, 60 Hz)
– 300–500 mA of DC
• AC at 120 V, 60 Hz is an especially dangerous because it
usually exceeds the let-go threshold
• Seriousness of the shock depends on current path
through the body
Ohms law E=IR
Aircraft Electrical Systems
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Quiz time
• Electricity is the ‘flow’ of:
a)
b)
c)
d)
Protons
Neutrons
Electrons
Klingons
Aircraft Electrical Systems
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Question 2
• In a DC circuit, the positive force used to make
the current flow is often obtained from:
a) Wall socket
b) Battery
c) Alternator
Aircraft Electrical Systems
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Question 3
• To keep a battery from depleting its ‘charge’,
rapidly (and perhaps burning up) each item to
be powered must provide some form of
electrical:
a) Capacitance
b) Inductance
c) Resistance
Aircraft Electrical Systems
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Question 4
• In a light bulb, the electrical resistance is in
the form of the:
a) Socket
b) Filament
c) Glass enclosure
Aircraft Electrical Systems
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Question 5
• In an electrical circuit, the amount of electron
flow is measured by the:
a) Ammeter
b) Voltmeter
c) Loadmeter
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Question 6
• The pressure of the electron flow is measured
by the:
a)
b)
c)
d)
Ammeter
Voltmeter
Dosimeter
Parkingmeter
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Question 7
• The purpose of a circuit breaker is to:
a) Sense current that may be too high for the
circuit.
b) Interrupt the flow of electricity to the ‘load’
c) Protect the airplane’s electrical wiring
d) Prevent an electrical fire
Aircraft Electrical Systems
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How much voltage does it take to kill a
person?
a) 15,000 volts
b) 120 volts
c) While voltage may be a factor, as little as 30
ma of current can cause ventricular
fibrillation..
Aircraft Electrical Systems
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What is a ‘short circuit’?
a) A direct path from a ‘ground’ to the positive
source of power
b) A abnormal low resistance connection
c) A possible destructive condition in an
electrical circuit
d) All of the above
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