How does a commutor retain residual magnetism in order to start?
By using field coils
What is the name of the rotating component in the magnetic circuit of the commutor?
Armature-creates its own magnetism when it rotates
What is the purpose of lap windings?
Stabilizes the magnetic field, keeps it from fluxuating
'Causes brushes to spark where there is potential difference' is defined by what term?
Armature Reaction
Who is power extracted off the commutator segments?
by using Carbon brushes
Name 3 types of generators
Series, Compound, and Shunt wound
Define Series Wound?
field and Armature are connected in series (not used on AC)
Define Shunt Wound?
field is in parallel with the load, if load increases, field decreases due to voltage drop across generator(used in AC)
What is the name of the coil that is stationary and uses both series and parallel coil?
Compund Wound
How can you define a offset commuator?
Correction Armature Reaction, can also use interpoles places in between main poles
Define the coming in speed on a generator?
The speed at which the EMF generatoores pushes electrons into the battery
Terminal I.D. on large generators
B
A
E
B-Power
A-coil
E-ground
Define A and B type generators
A-points after field
B-points before field
Name 3 tests performed on a generator to test for serviceability?
Open Windings, Shorted Windings, Grounded Windings
How do you test for open windings?
mulit-meter-commutotor to shaft
How do you test for Shorted Windings?
Check for insulation leak or bridging commuator with hack saw blade
How do you check for grounded windings ?
insulation leak to ground, check with a multi-meter
How dows a alternator differ from a generator?
produces lots of flux and magnetic power at low RPM, produces rated power at low RPM. contains an electromagnetic coil that produces lines of flux for the rotating field
What are the two configurations of alternators?
Y and Delta wound
How is a CSD controlled?
flyweights
How does a intergrated Drive Generator work?
changes RPM to provide a constant RPM to generator
How could you describe a Var. Speed Constant Freq?
Solid state circuity converts output of generator to constant freq delivered to bus
Define a rotary inverter?
Input DC to a DC motor that turn at a constant speed. Output is AC from a single phase. DC excitiable field to vary output.
Define a Static Inverter?
DC Input, solid state circuity produces AC output
What is the difference between an inverter and a rectifier?
Inverter-DC to AC
Rectifier-AC to DC
In a solid state regulator, what can conduct electricty if its reversed biased?
Zener diode
The power supplied to the alternator field of a DC alternator is?
DC
How is the battery connected to the A+ terminal of the alternator prevented from discharging through the alternator?
Diodes in the rectifier
Name 3 devices used to regulate speed ?
IDG
CSD
VSCF
What supplies power for the field to the exciter generator in a high output brushless alternator?
Permanet Magnet
if you spin a DC motor, it will generate electricty. True/false?
True-residual magnetisum
What 2 components are required in a DC motor?
Field and conductor
What are some of the factors effecting torque in a motor?
current going through the armmature
strenght of the magnetic field
the number of poles
number of windings on armmature
position of coil in the field
What type of application would you used a series wound DC motor?
high torque at low speed-starter, flaps
What type of application would you use a shunt wound DC motor?
constant speed applications fan field is in parallel with armmature
How can you control the speed of a series wound motor?
By varying the current through the armmature, bypass armmature with rehorstat
Whats a reversible DC motor?
Split Field, 2 field winding wound in different directions
How can the polarity of a reversible DC motor be changed?
by using a double pole double throw swithch
What is the part called in a AC motor that rotates?
Squrriel cage
Name 3 types of AC motors
Universal
Induction
Synchronous
Define a universal Motor?
Will operate on both AC and DC
can be reversed easily
uses commutator and brushes
How does the Induction motor produce electricty?
uses pole shoes that create a magnetic field but also induce current flow into squirrel cage (no physical connection)
How is torque generated for starting a AC motor?
Capacitors and Stators cause field to be out of phase to generate starting torque
How is a 3 phase AC motor wired so it will start?
wired so it will induce current at any point
self starting
can be reversed by changing leads
What are the 3 energy losses in electric motors?
Electrical-copper loss due to heat generated
Iron-Hyeteresis, residual magnetisum due to electromagnetism, resist magnetism in opposite direction
Eddy Current-current flowing in armature core, material and field cause heat to build up
Define electrical load analysis, and when is it done?
The summation of electrical loads as defined by the equip manufacturer
-must be done if your going to modify electrical system
Where would a ammeter be located in a electrical system?
between the battery and the bus
define three thing about the hot bus?
essential loads
emergency loads
no disconnect
What is a inverter used for ?
Used to provide varying AC voltages in AC circuit
"divided so you can isolate breaker so you can still fly if you were to lose a component" is a definition of what type of system?
Split bus
What does a limit switch do when activated?
cuts off power to the motor
What type of aircraft would you typically find a split bus system?
twin engine
What are some benifits to the split bus system?
buses never interact with each other
prevents phasing problems with AC current
prevents out of phase generators
What type of aircrafts would use a parallel bus ?
3+ engine a/c
What type of transformer is clamped over a unshielded wire and induces AC into sensing field?
Current Transformer
What does GCU
GFR
F
KW
GB
BTB
Generator Control Unit
Gen. Field Relay
Frequency
Kilowatts
Generator Breaker
Bus Tie Breaker
What is a TX buss
TR
EXT POWER
Transfer Bus-feeds battery charger
Transformer Rectifier-turns AC to DC for Bus
External Power
What does BITE stand for?
Built In Test Equipment
Name as many wiring considerations as you can?
design temp
flexibility
Abrasion resistance
Strength
Insulation
electrical resistance
weight
applied voltage
current flow
What is the major differnece between copper and silver wire?
copper corrodes
What are two benifits of shielded wire?
eliminate radio interference
prevents voltage from being induced into the circuit
What are co-axial cables used for ?
used for connecting an antenna to its radio reciever or transmitter
What is the Standard for wires ?
No standard, all manufactures have there own legend
