Basic Electrical Theory I
What is ohms law?
E=IxR
Voltage=Current x Resistance
What formula is used to find resistance in a parallel circuit?
Total Parallel Circuit:
RT=1/(R1)+1/(R2)+1/(R3)...
If the reciprocal of both sides is taken:
RT=1/(1/(R1)+1/(R2)+1/(R3)
What is the standard AC voltage and frequency used on aircraft?
115 VAC @ 400 Hertz
Describe electromagnetic induction.
Electromagnetic induction is the process of producing a voltage (EMF) by moving a magnetic field in relationship to a conductor.
When a conductor (wire) is moved through a magnetic field, an EMF is produced in the conductor. If a complete circuit is connected to the conductor, the voltage also produces a current flow.
What is the component that converts DC into AC?
Inverter
What formula is used to find the total resistance in a series circuit?
RT=R1+R2+R3...
What is the advantage of using AC instead of DC?
1. It is easier to step up or down the voltage.
2. Higher voltage can be used (lighter wires).
How do we control voltage and current output from a generator and alternator?
By the use of a voltage regulator.
What is Static and Current Electricity? Describe each one.
Static Electricity - Stationary electrical charge.
Current Electricity - Useful type with actual flow.
What are the units of measurement of resistance and power in an electrical circuit?
Resistance - Ohms
Power - Watts
What is Inductive Reactance?
The opposition of current flow...
This is also known as Counter EMF and it will caules phase shifting...
What is the RCCR and what is its purpose in the voltage generator?
Reverse Current Cutout Relay...
Using a voltage regulator and a current limiter, the RCCR automatically disconnects the aircraft battery from the generator as soon as the generator voltage drops to less than the voltage of the battery.
What are the five different methods of creating electricity?
Chemical, Heat, Light, Pressure, Magnetism
What are the three things needed for electromagnetic induction to work?
Electromagnet
Voltage (EMF)
Relative Motion
What is Phase Shifting and how is it controlled?
In AC circuits, the Voltage and Current may not reach the same amplitude peaks at the same time, they generally have a difference in timing. That difference in timing is called Phase Shift and is controlled with a control on the outside of some generators that are series wound...
How do we rectify AC Into DC on generators.
By the use of slip rings, brushes and commutators.
The amount of electrical current that is produced by a generator is dependent on what three things?
1. The strength of the magnetic field.
2. The number of conductors passing through the magnetic field.
3. The speed of the conductors that are passing through the magnetic field.
During the process of electromagnetic induction, the value of the induced voltage/current depends on three basic factors...
1. Number of turns in the conductor coil (more loops equals greater induced voltage).
2. Strength of the electromagnet (the stronger the magnetic field, the greater the induced voltage).
3. Speed of rotation of the conductor or magnet (the faster the rotation, the greater the induced voltage).
Describe Impedance, what letter represents it?
The total opposition to current flow in an AC circuit is known as impedance and is represented by the letter (Z).
What is the difference between electron current and conventional current?
Electron current goes from the negative terminal, it is the actual flow of electrons in a circuit.
Conventional current Is an imaginary flow of electricity that flows from the positive terminal to negative.
Pg. 497