MOD 3-4 Flashcards by Carolina Herrera

What is a capacitor?

a device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator

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What other device stores electric charge that you can buy at any store?

Battery

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In relation to electronics what is Tau?

Time constant

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To get the total capacitance you ___ capacitor values when wired in Parallel, and use the formula get the total capacitance when wired in series.

ADD C total ______1__________

_1_ + _1_ + _1_

C1 C2 C3

get the total capacitance when wired in series.

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What makes capacitors dangerous?

They store a charge, that can be present even when power to a circuit is turned off

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Capacitors Block____ and PASS ____

DC - AC

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Capacitors resist a change in voltage while inductors resist a change in

Current

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When electricity flows through a wire it creates a ______ field, when you move a wire through a ______ field it creates _______

Magnetic- Magnetic - Electricity

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Capacitors are measured in _____ Inductors are measured in _______

farads and henrys

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What is the formula for Tau in an inductive circuit?

T=L/R

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What is the formula for capacitive reactance?______, this means that as the frequency increases the capacitive reactance will ________.

Xc=1/2πfC - DECREASE

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What is the formula for inductive reactance? _______, this means that as the frequency increases the inductive reactance will ________.

XL=2πfL, INCREASE

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What is the lowest frequency you can get? ____HZ, or DC. If I plug this in to the above equation’s XC will equal _______ and XL will equal ___. So for DC a capacitor looks like a _____, and an inductor looks like a short (just a piece of wire).

0 HZ - INFINITE 0HZ - OPEN

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Reactance is?

Is a form of opposition like resistance in an AC circuit made up of Xc, XL and resistance to form an overall impedance, or total opposition in an AC circuit.

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The Inductance is ________ proportional to the length of the coil at a constant number of turns.

inversely

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ELI stand for?

The Voltage “E” leads the current “I” in an inductor “L”

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ICE stands for?

Current “I” in a capacitor “C” leads the voltage “E”

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How do capacitors store energy?

Capacitors store energy in the form of electrostatic fields

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Voltage lead current in a ______ circuit.

Inductive

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Z or impedance is the vector sum of

Capacitance reactance Xc, Inductive reactance XL, and resistance R.

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Resonance is when XC and XL

Equal

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Transformer can only be used in a_______ circuit, because a coil of wire is really just a short to DC voltages.

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IF the primary side of a transformer (the side I’m putting AC voltage in to) has 2 turns and the secondary side (the side I’m taking voltage out of) has 4 turns, and I put 1 volt AC on the primary I will get ___ Volts AC on the secondary

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The AC voltage coming out of a plug in the wall is 120VRMS, my phone only needs 5 VDC to charge, so I could use a transformer with a ____: ____, turns ratio to step down the 120 volt to 5 volts so my phone does not blow up when I plug my charger into the wall

24:1

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True, actual, or real AC power is measured in\_\_\_\_\_, and is the Beer in the glass (A2).

Watts

Reactive power is measured in \_\_\_\_, and is the foam in the class of beer (B2)

VAR

Apparent power is measured in \_\_, and is the “C2 “, in the good old formula A2+B2=C2

Power factor is the ratio of _________ power and apparent power. In a purely resistive circuit the power factor would be \_\_\_, meaning 100% of the power would be doing work.

TRUE or REAL , 1

In the diagram I’m paying for VL, but only using Vr to do actual or real work. Going back to what we have learned about impedance, what could I install on all my motors, so to the power company it looks like I only have a resistive load, and only pay for Vr saving my company a ton of money?

BIg Capacitors

If I move a conductor in relation to a magnet I make

Electricity

A coil of wire becomes a ______ when I run electricity through it

magnet

he more current I pass through the coils of my electro magnet the greater the magnetic \_\_\_\_\_\_becomes.

Field

The stronger the magnet field is that I pass my conductor through, the more _______________________________ will be induced in my Conductor

CURREN/VOLTAGE/ELECTRICITY

If I rotate my conductor at the same speed through my electromagnet, and I want to increase or decrease the amount of electricity (Voltage) in the conductor, all I would have to do is increase or decrease the voltage to my \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.

ELECTROMAGNET/FIELD.

To make electricity I can either rotate the _______ in relation to the _______ or rotate the _______ in relation to the \_\_\_\_\_\_

MAGNET- CONDUCTOR-CONDUCTOR-MAGNET

In AC generation the conductor portion that has electricity induced into it by the magnet FIELD is called .

armature

Magnet have a ______ and _____ POLE.

NORTH -SOUTH

Changing how fast I rotate the magnetic FIELD in relation to my conductor (armature), will change the ___________ of the AC voltage I get out.

FREQUENCY

The formula for the frequency of an AC alternator/generator is \_\_\_\_\_\_\_, where P=number of magnetic poles (always even), N=The speed of rotation in RPM, and the 120 is just the conversion from Minutes to seconds (RPM is in minutes frequency is in seconds or / by 60) and from poles to pairs of poles (always use 2, thus 60 X 2=120)

f=PN/120

So if I wanted to change the frequency of the AC voltage coming off the armature of an AC generator I could change the ________ of rotation or the number of _____ I build into my generator

SPEED/RPM- POLES

I go buy a generator from the store and now I am forever going to be stuck with the number of poles that it came with, the only way I can change the frequency now is to change \_\_\_\_\_\_\_

SPEED/RPM

I now have a problem, I need my generator/alternator to always output 400Hz (so a fixed speed), and my engine speed (RPM) that it is hook up to changes all the time, I solve this by using a

CONSTANT SPEED DRIVE/CSD

To clear some stuff up what is the difference between an Alternator and a Generator?

The alternator converts mechanical energy into AC while a generator converts it into both AC and DC. Alternators have a rotating magnetic field, and a generator has a stationary magnetic field. Alternators receive energy supply from the stator, and generators receive that supply from the rotor.

If we combine the Generator and CSD into one unit we call it a

INTERGRATED DRIVE GENERATOR.

In a “Generator” I rotate the armature (the conductor I’m inducing the voltage into), and I need to supply this induced voltage to my loads that draw 100’s of amps, I do this using _______ that provide the mechanical connection to the spinning armature through the Commutator.

BRUSHES

If I stick my shoe on the pavement while driving down the road (shoe=brush, pavement=commutator) it is going to \_\_\_\_\_\_\_\_, and I’m going to want check this wear often to make sure I always have some shoe/brush left

WEAR OUT

We need the electricity we are making with the generator to have a fixed frequency and a fixed voltage (115V and 400Hz), with very tight tolerances, so we don’t blow up all the very expensive Avionics equipment on an aircraft. We control the frequency using a \_\_\_\_\_\_, and we can control the voltage by varying the ___________ of the magnet field, by changing the voltage to it.

CSD- STRENGTH

When the voltage from my generator drops due to an increase in load, I will have to\_\_\_\_\_\_ the voltage to the magnetic _____________ to compensate, and ______ the voltage to the field when the load decreases, in order to keep the output volt constant, we call this \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.

INCREASE- FIELD (MAKE IT STRONGER)-DECREASE- VOLTAGE REGULATION

When we put all the thing we want to control and monitor in the alternator/generator system (Voltage regulation, overcurrent protection, overvoltage protection, frequency and phase monitoring) into one box, we call it a ______________ or ____ for short.

GENERATOR CONTROL UNIT

AC motors are just like AC Generators, except for a generator I put mechanical energy in and get AC power out and a MOTOR I put _______ in and get \_\_\_\_\_\_\_\_\_

AC power-Mechanical energy out.

The 3 main types of AC motor are?

Universal, Induction and synchronous.

The type of motor most commonly found on aircraft is the \_\_\_\_\_\_\_

Induction

A Universal Motor is called that because it can be driven with both \_\_\_\_\_\_\_\_, you can tell the motor you are looking is a universal one because it has \_\_\_\_\_.

AC and DC-Brushes

You install a 3 phase motor, and when you go to test it, it runs backwards, what is the most probable cause \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_(done at the overhaul facility of course)

Two phases are swapped

All AC motor have data plates, where we can find all sorts of information, the most important thing to look at right off the bat would be what \_\_\_\_\_\_\_\_it needs to run, and what ________ that voltage is. Because if I hook a 115V/60Hz motor up to 208V at 400Hz I would let all the smoke out.

Voltage- Frequency

The two main parts of an Induction motor are the ______ and the \_\_\_\_\_.

stator -rotor

Single phase induction motors are inherently hard to get up and running, two ways we overcome this are to use __________ or \_\_\_\_\_\_\_\_

Shaded poles - Capacitor start

With a Generator we were concerned with what frequency it produced for a give speed we drive it at, and use the equation \_\_\_\_\_\_. But with a motor it would be nice to know how fast it’s going to turns or “N” (RPM), so we just rearrange it to solve for N and get\_\_\_\_\_\_, where P=\_\_\_\_\_\_\_, f=\_\_\_\_\_\_\_, and N = RPM.

f=PN/120 - N=120f/P Number of poles Frequency

Some advantages of AC motors are?

More power to weight Easier to build, less expensive Some don’t need brushes, less wear and tear, last longer with less maintenance

capacitor look like \_\_\_\_\_\_to DC voltage

OPEN

the inductance current will flow in the opposite direction (Lenz Law ) and is called \_\_\_\_\_\_\_\_\_\_for that reason

counter EMF

capacitance in series when the dialectric thikness increases the circuit is less \_\_\_\_\_\_\_\_

capacitance

capacitance in parallel when the plate area increases the capacitance \_\_\_\_\_\_\_

Increases

Inductance is proportional to the numbers of \_\_\_\_\_

turns squared

Inductances varies in direct proportion to the \_\_\_\_\_\_\_\_

Cross-sectional area

inductance varies in inverse proportion to the lenght of the coil at constant \_\_\_\_\_\_

number of turns

inductor oppose the change on \_\_\_\_\_\_and capacitor oppose the change on in \_\_\_\_\_\_

current-voltage

inductors are \_\_\_\_\_\_\_\_\_devices and capacitors are \_\_\_\_\_\_\_\_devices

electromagnetic - electrostatic

t (tau) fro an inductance circuit is\_\_\_\_\_\_ and t(tau) for capacitance is \_\_\_\_\_

L/R R X C

Why we used trasformers ?

less amperage to be able to run light wire

power factor formula

true power/ apparent power

criteria of a good solder

shiny, smoth, good penetracion, no excess solder

the magnetic field can be stationary and voltage induce into roatring armature is generally consider a

generator

the magnetic field can be rotated and the voltage is induce into a stacionary coil (winding) is consider as an ?

alternator

advantages of AC motors

- constant speed - Easer to buidl, less expensive - more power lees weight less MTC

the direction of the rotation in a 3-phase induction motor can be change by ?

interchanging any two stators winding connections

the synhronous rotation speed (RPM) of an AC motor can be determined by this formula

N=120f / P ## Footnote f= frecuency P=number of poles

difference between actual speed and sychronous speed is called

SLIP

3 phase inductor motor does not required any additional \_\_\_\_\_\_\_devices

starting

two method of starting a sigle phase induction motor

- shaded poles - capacitor start