ELECTRIC GENERATORS AND MOTORS

list two advantages of Alternating Current

-transformer operation (essential in x ray equipment) -power loss when transmitted over long distances

wave form with two commutator segments results in

100% ripple, and wave from sent to the loads

what is the percentage ripple in a single DC generator

100% ripple, the current goes from minimum to maximum back to minimum (0-100)

a 3 phase pulse is produced

120 degrees after the prior wave

what are the two types of electric motors

AC motor DC motor

to induce electric current in a circuit some parts of the circuit must be changing in the magnetic field

EMI

power loss/heat loss formula

P= I2R

describe a solenoid

a coil of wire with current flowing through it

Faraday's law requires

a conductor a magnetic field relative motion b/w the magnetic field and conductor

explain the principle of a electric motor

a current carrying conductor will be placed in the magnetic field, there will be a force trying to push the conductor out/upward the magnetic field because it distorting it (bending it)

describe a commutator

a metal slip ring divided into 2 pieces white and black ring that reverses the current flow

describe a electromagnet

a solenoid with a iron rod

describe a current carrying conductor

a wire that has current flowing through it

in a AC motor induction why does voltage have to be induced into the rotor via EMI, causing the rotor to rotate/turn

because there's no power is being supplied to rotor, it has no slip rings, brushes, commutators, no physical electrical connection

what makes a DC generator different from a AC

commutator and brushes on external circuit

DC motor uses

commutators

Define electric generators (dynamo)

converts mechanical energy into electrical energy by using EMI

AC motor induction the rotor is ________ bars around ______ that looks like a squirrel cage

copper, iron core

Alternating Current

current is changing directions constantly through the external circuit (loads)

for the right hand rule the middle finger

direction of current flow

for the right hand rule the thumb

direction of motion of the conductor with the respect to the magnetic field

for the right hand rule the index finger

direction of the magnetic field (N to S)

define cycle

from the start from one wave to the start of next consecutive wave

where does AC and DC produce current?

inside of the machine

wave form with multiple commutator segments results in

less ripple in the wave form sent to the loads

the simple electric generator consists of

magnetic field (electromagnet/stator), armature (rotor), slip rings, brushes, external circuit,

reversal of the conductors in the _________, leads to the reversal of the polarity of the ____________ (current flow changes direction) then leads to reversal of _________ flow that results in ______

magnetic field, induced voltage, current, AC

define ferequency

number of cycles per time hour/day/week etc

AC synchronous motor

occurring at the same time, current is applied to both armature (rotor) and the powerful electromagnet (stator) from the same source (same frequency)

alternations/impulses; 2 per cycle is

one positive and one negative 120 sec with 60 Hz

with a AC induction motor the current is only supplied to the

powerful electromagnet (stator)

a motor _______ energy

receives

direction of motion (rotation) of the conductor is determined by the ________________

right hand rule for motors

AC synchronous motor rotates at the same speed with ________

rotor of the generator supplying it generator speed = 3600rpm motor speed=3600rpm

AC synchronous motor uses

slip rings

a AC generator has

slip rings and brushes on external circuit

the powerful electromagnet (stator)

stationary portion field magnet that produces a magnetic field

a generator _________ energy

supplies

AC Motor has two different types

synchronous and induction

what is ripple?

the amount of curvature in the wave

define electric motors

the conversion of electrical energy to mechanical energy

what is motor action? (how a motor works)

the interaction of two magnetic fields

both electric motors and electric generators are the same except for what in electric motors?

the power is being supplied to the motor itself, power is going in

what are the two main parts of a generator

the powerful electromagnet (stator) and the armature (rotor)

the armature (rotor)

the rotating portion, many turns of wire rotated in the magnetic field which is set up by the field magnet

list four ways mechanical energy for rotation can be supplied

turbine electric motor engine (gas or diesel) wind power

peak values (P)

values of V or I at the peak of the curves