Electricity test 2

35問 • 2年前

問題一覧

Slip rings are used in alternators to carry _____ current to the load, while a commutator is used to carry ____ current to the load.

Alternating current & direct current

Do All generators have brushes?

A generator without brushes is called a ____ generator.

Brushless

What are some advantages of “brushless alternators” over “slip-ring type” ?

•More reliable because no moving parts •Less maintenance required •No chance of brunch arcing at high altitudes where atmosphere is thinner.

Which “semi-conductors” are used to rectify AC in a “brushless alternator” ?

Diodes

How many diodes are needed to fully rectify single phase AC without using a centre-tap transformer?

4- diodes

How many diodes are needed to fully rectify “THREE-phase AC”?

6 diodes

While In flight what is the easiest method of controlling “generator output voltage”?

To vary the strength of the field current

What is the purpose of a CSD?

To provided constant frequency of 400hz to generator regardless of engine speed

And IDG combines a ___ and a ______. ?

CSD & Generator

In the event of an IDG malfunction what would the flight crew do?

Manually disconnect the IDG using the appropriate disconnect switch

List three operating conditions of a CSD

•Straight through drive •Overdrive •Underdrive

A “three unit voltage regulator” is made up of a ____ regulator _____limiter and a ____relay.

•voltage regulator •current limiter •reverse current relay

A reverse current relay is also know as?

“Reverse current cutout relay “

The purpose of a reverse current relay is to ____ a generator from _____ the battery when the generator output is ____ than battery voltage

•prevent •discharging •less

How would a generators output voltage be affected by a stuck open contact in a vibrating voltage regulator?

Output voltage will “decrease” since the field current will be forced to always flow through the resistor

If a rectify changes AC to DC, then an ____ changes DC to AC.

Inverter

List two types of “inverters”

•rotary •static

Large transport category aircraft use inverters when they have lost power from an _____?

AC power source like a generator or alternator

Biz jets and light aircraft use inverters ___?

Part time

What is a TRU?

Combines a transformer and a rectifier in one unit

What does a TRU do on an aircraft?

Converts 120V AC power into 28V DC power

On large transport category aircraft where is a static inverter most likely to be Installed?

Electronics equipment bay or avionics bay

How many magnetic fields are there in an AC motor?

Two

The stator magnetic field in an induction AC motor induces a _____ in the rotor that produces a second ____ field.

• ”current” in the rotor • “magnetic” field

A three-phase AC motor produces a ____ magnetic field?

Rotating

A “single phase” AC motor produces a _____ magnetic field.

Pulsating

How many magnetic fields are there in a “synchronous” AC motor?

How many different power sources can a “synchronous” AC motor have?

I’m some designs, an AC synchronous motor will have ____current flow through its stator (sometimes called an armature while ______ current flows through the rotor.

•“Alternating” current flow •Direct

What is “motor slip” ?

The “difference” in rotational speed between the rotor and the stators rotating field

Motor slip calculation

( Synchronous speed - rotor speed) / synchronous speed)) X 100

Devices that operate using single phase synchronous motors?

Electric clocks, engine instrument

AC Motor maintenance

•Bearing may or may no need frequent lubrication depending on type of bearing. •Coils kept dry and free from oil •temp too hot for hand is too high for safety

AC Motor good sound vs bad sound when doing maintenance

Good sound = hum Bad sound = grunts

Composites test 2

Zachary Halycz · 54問 · 2年前

Composites test 2