11.6 Electrical Power Flashcards
Why is an integral grey collar fitted to certain CBS?
To indicate theta they must be pulled by maintenance personnel during maintenance work
A hot battery bus is always what?
Directly connected to the battery
Why is an integral orange collar fitted to certain CBS?
To indicate they must be pulled by flight crew in certain abnormal situations
Why must you never attempt to carry out too many APU starts immediately after one another ?
It will overheat the battery and damage it
What should you do if the electrolyte used in NI-Ce battery comes into contact with human skin?
Rinse it immediately making sure you only use clean water
What does OVERDRIVE mean in relation to CSD operation?
The output speed of CSD is faster than the input speed
What’s does UNDERDRIVE mean in relation to CSD operation?
The input speed of the CSD is faster than the output speed
What is the main source of electrical power while the AC is on the ground?
External power
What is the main advantage of parallel operation of main AC bars?
There is no power loss at failure as another takes over
What is CSD?
Constant speed drive
How is CSD cooled?
With oil
What is the rotational speed of CSD?
12000rpm
How are engine driven generators connected
Parallel
Frequency and voltage of AC?
400Hz
115V
Voltage of DC?
28V
How many batteries are there in an aircraft?
2
What usually powers AC consumers in flight?
Engine driven generators
What usually powers AC consumers in ground?
GPU or APU
When are emergency generators released?
At total loss of all other AC power sources
What does a red tag do?
Prevent someone from putting circuit breakers back in
What is the phase difference of AC?
120 degrees
What’s do TRU’s do?
Transform 115v AC to 28V DC
What are batteries used for?
APU start emergency power
What electrolyte is used in ni - cad battery?
Strong alkaline
What is the lowest voltage a battery should get to?
22V
What are the 2 short pins of the ground receptacle used for?
Will disconnect power if it comes out
Also guide pin
Does an AC circuit use CBs or fuses?
Circuit breakers
What is the main task of a fuse/ CB?
.Prevent overheat and fire due to a short circuit
.prevent currents higher than the max allowance for that cross sectional wire
What does the essential power distribution consist of?
Supplies all systems that are necessary to operate the aircraft safely
How much energy does a 2 and 4 engine aircraft need?
2 = 100kw
4 = 400kw
What are two ways for DC power generation?
. Transformer rectifier units (TRU)
. Batteries - nickel cadmium
