FINALS QUESTIONNAIRES Flashcards
What part of DC Generator acts as a rectifier?
Commutator
Is a rotating machine that supplies an electrical output with unidirectional voltage and current?
DC Generator
Losses which occur because of friction between the parts of the generator.
Mechanical Losses
These are the generators whose field magnets are energized by some external DC Source, such as a battery.
Separately Excited DC Generator
A form of two-layer winding for electric machines in which each coils is connected in series with one adjacent to it.
Lap Winding
Its main function is to supply magnetic fields around which the coil spin.
Stator
The field winding of this generator is connected in parallel with the generator armature.
Shunt Wound Generators
Is a mechanical piece in a DC machine that produces the rotational of a force known as torque and brings about rotation.
Shaft
It is made up of soft iron laminations which are insulated from each other and tightly clamped
together
Armature Core
These generators are generators whose field magnets are energized by the current supplied by themselves
Self Excited DC Generator
His armature consists of an iron ring with projecting teeth interspeed with coils which formed a closed series circuit with connections to a commutator.
Antonio Pacinotti
The.__________, component must be properly adjusted to what is called “neutral” position
Yoke
For a cumulatively compound motor, torque at starting is greater than a ________?
Shunt Motor
It has linear relationship existing between the field current and the amount of torque produced.
Series Wound Motors
It is used to create mechanical revolutions and includes all the rotating electrical parts.
Rotor
This type of DC motor has good regulation and it is also classified as a constant speed motor even though its speed does decreases slightly with an increase in load.
Shunt Motor
Which type of DC motor has the same speed control techniques available as those available for a shunt motor? (scroll down for choices)
A. Cumulatively compounded DC motor
B. Differentially compounded DC motor
C. Both A and B but since B is almost never used, that fact hardly matters.
D. Neither A and B because each type of DC motor has a unique formulation.
C. Both A and B but since B is almost never used, that fact hardly matters.
Type of self excited de motor in which the field windings are exposed to the entire terminal voltage as they are connected in parallel to the armature winding.
Shunt Wound DC Motor
This type of permanent magnets are susceptible to high temperatures and become demagnetised. It can last over a 10 year period the loss in magnetic power would be un-noticeable.
Rare-earth Magnets
Using Fleming’s Left Hand Rule, we can determine three parameters which are:
A. Magnetic Force
B. Direction of Current
C. Magnetic Field
D. All of the above
D. All of the above
A transformer cannot be connected to the _______ because it will produce a steady current.
DC Supply
Simply the generation of an induced EMF in a coil as a result of current flowing in an adjacent coil.
Electromagnetism
At which category (Type) of transformer does a Distribution Transformer fall into
Step Down Transformer
_____________ type of transformer which operates on single-phase power.
Single Phase Transformer
Transformer’s work on which principle/law?
Faraday’s law of mutual induction
In calculating efficiency transformer what is the value of Pc?
I1^2R1+I2^2Ro2
What is the formula to get transformers EMF?
EMF=4.44FNØm
Use of __________ transformer system (a series system) in the first large exposition of AC power in Turin, Italy.
Lucien Gaulard’s
Lucien Gaulard and John Dixon Gibbs first built a _______ or in today’s terminology a step down transformer which they designed with open iron core, the invention was not very efficient to produce.
Secondary Generator
________________ type of transformers that are used to change voltage of electrical systems with three-phase.
Three Phase Transformer
“Father of three-phase current”
Galileo Ferraris
They had worked on motor, but it had a commutator.
Stanley and Thomson
An important year for AC power.
1886
In 1886 designs an improved version of the Siemens single phase alternator
William Stanley
When did Charles Proteus Steinmetz publishes introduces new mathematic solutions to solve puzzles of the behavior of AC power with his article: “Note on the Law of Hysteresis” in Electrical Engineer issue number 137.
December 17, 1890
is a kind of electric generator used in contemporary cars to run the electrical system while the engine is running and to charge the battery.
Automotive Alternators
These generators are taken two at a time and run sequentially with a 120 degrees offset between them.
Three-Phase AC Generator
The function of an
________________________ is to provide a steady stream of electrical energy
to power all electrical devices and components within a machine
Alternator
is used to convert current from alternating current (AC) to direct current (DC) during the charging process.
Rectifier
is a machine that converts the MECHANICAL ENERGY into AC ELECTRICAL POWER.
AC Generator
The stator is the stationary part of the motor’s electromagnetic circuit and is made up of thin metal sheets, called laminations.
Stator Core
is a 1-phase motor that includes a stator as well as a rotor with a single cage.
Capacitor Start Induction Motor
As the rotor coils are short-circuited, according to _______________, the current will start flowing through the coil of the rotor.
Faraday’s law of electromagnetic induction
Coils of insulated wire are inserted into slots of the stator core
Stator Winding
is a part of the motor used for the protection of the motor from the environment and persons from being touch.
Enclosure
An alternate name of ____________ is a Resistance Start Motor
Split-Phase Induction Motor
Conceives the idea of the first polyphase AC motor.
Galileo Ferraris
Builds his first transformer and motor to work with his 3 phase AC system.
Dobrovolsky
A _________________ gets produced in the stator due to the flow of current in the coil..
Magnetic Flux
It is mounted on the shaft, support the rotor and allow it to turn.
Bearings
Synchronous motors are generally not self-starting because…
…the direction of instantaneous torque reverses after half cycle
A synchronous motor can develop synchronous torque…
…only at synchronous speed
Synchronous motor always run at…
…the synchronous speed.
Synchronous motor are…
A. not- self starting
B. Self-starting
C. Essentially self-starting
D. None of the above
A. not- self starting
In a synchronous motor, which loss varies with load?
Copper loss
the rotor copper losses, in a synchronous motor, are met by…
…DC Source.
In which of the following motors the stator and the rotor magnetic field rotate at the same speed?
A. Universal Motor
B. Synchronous motor
C. reluctance motor
D. Induction motor
B. Synchronous motor
Is the rotor loss being relatively smaller than stator loss due to the small DC rotor current flowing through the field winding?
Rotor Loss
Is made of silicon steel material. It provides an easy path for the magnetic lines of force and accommodates the stator winding
Stator Core
It is a type of losses that occur in the core or the iron parts of the synchronous motor due to the magnetic property of the material.
Iron and Core Losses
