Midterms Flashcards
does not create energy. It changes mechanical energy into electrical energy.
Generator
The outer frame of a dc machine is called as ______\. It is made up of cast iron or steel.
Yoke
serve two purposes; they spread out the flux in the air gap and also, being of larger cross- section, reduce the reluctance of the magnetic path they support the exciting coils (or field coils).
Poles and Pole Shoes
They are usually made of copper. Field coils are former wound and placed on each pole and are connected in series.
Field Winding
is the rotor of a dc machine. It is cylindrical in shape with slots to carry armature winding.
Armature Core
It is usually a former wound copper coil which rests in armature slots.
Armature Winding
consists of a set of copper segments which are insulated from each other.
Commutator
They rest on commutator segments and slide on the segments when the commutator rotates keeping the physical contact to collect or supply the current.
Brushes
Brushes are usually made of
Carbon or Graphite
are those whose field magnets are energized from an independent external source of DC current.
Separately Excited Generators
are those whose field magnets are energized by current produced by the generators themselves.
Self Excited Generators
the field windings are connected across or in parallel with the armature conductors and have the full voltage of the generator applied across them.
Shunt Wound
the field windings are joined in series with the armature conductors
Series Wound
: it is a combination of a few series and a few shunt windings
Compound Wound
Compound Wound can be:
Short shunt or Long shunt
is a type of electric machine that converts electrical energy into mechanical energy.
DC Motor
DC motors include two key components
a field coil or stator or permanent magnet and an armature or rotor.
is an AC (alternating current) device that transfers power from one circuit to another without a rotating part and change of frequency.
Transformer
IT WORKS ON THE PRINCIPLE OF
MUTUAL INDUCTION
– is the basis of a transformer between two circuits linked by a common magnetic flux.
Mutual Induction
work with electromagnets and discover the property of induction independently on separate continents.
Joseph Henry and Michael Faraday
invents the
induction coil.
Rev. Nicholas Callan of Maynooth College
uses induction coils in his lighting system
Pavel Yablochkov
uses induction coils in their lighting systems with AC incandescent systems.
The Ganz Company
designs one of the earliest AC power systems with William Thomson (Lord Kelvin). He creates an early transformer.
Sebastian Ziani de Ferranti
first built a “secondary generator” or in today’s terminology a step down transformer which they designed with open iron core, the invention was not very efficient to produce. It had a linear shape which did not work efficiently.
Lucien Gaulard and John Dixon Gibbs
is a type of transformer with the function of converting low voltage (LV) and high current from the transformer’s primary side to high voltage (HV) and low current value on the transformers’ secondary side.
The step-up transformer
is a type of transformer that converts high voltage (HV) and low current from the primary side of the transformer to low voltage (LV) and high current value on the secondary side of the transformer.
The step-down transformer
The structure of core of this transformer is in the form of a rectangular frame made from cold rolled grain oriented sheet steel (C.R.G.O.) with thin silicon steel laminations.
Core-type construction
the magnetic circuit (core) surrounds a considerable portion of the windings.
Shell-type construction
