DC Generator working principle


DC Generator working principle



An electrical generator is a device that converts mechanical energy to electrical energy, generally using electromagnetic induction. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, or any other source of mechanical energy.
The Dynamo was the first electrical generator capable of delivering power for industry. The dynamo uses electromagnetic principles to convert mechanical rotation into an alternating electric current. A dynamo machine consists of a stationary structure which generates a strong magnetic field, and a set of rotating windings which turn within that field. On small machines the magnetic field may be provided by a permanent magnet; larger machines have the magnetic field created by electromagnets.
The energy conversion in generator is based on the principle of the production of dynamically induced e.m.f. Whenever a conductor cuts magneticic flux , dynamically induced e.m.f is produced in it according to Faraday's Laws of Electromagnetic induction.This e.m.f causes a current to flow if the conductor circuit is closed. Hence, two basic essential parts of an electrical generator are (i) a magnetic field and (ii) a conductor or conductors which can so move as to cut the flux.

Generator Construction:

Simple loop generator is having a single-turn rectangular copper coil rotating about its own axis in a magnetic field provided by either permanent magnet or electro magnets.In case of without commutator the two ends of the coil are joined to slip rings which are insulated from each other and from the central shaft.Two collecting brushes ( of carbon or copper) press against the slip rings.Their function is to collect the current induced in the coil. In this case the current waveform we obtain is alternating current ( you can see in fig). In case of with commutator the slip rings are replaced by split rings.In this case the current is unidirectional.

Components of a generator:

Rotor: In its simplest form, the rotor consists of a single loop of wire made to rotate within a magnetic field. In practice, the rotor usually consists of several coils of wire wound on an armature.
Armature: The armature is a cylinder of laminated iron mounted on an axle. The axle is carried in bearings mounted in the external structure of the generator. Torque is applied to the axle to make the rotor spin.
Coil: Each coil usually consists of many turns of copper wire wound on the armature. The two ends of each coil are connected either to two slip rings (AC) or two opposite bars of a split-ring commutator (DC).
Stator: The stator is the fixed part of the generator that supplies the magnetic field in which the coils rotate. It may consist of two permanent magnets with opposite poles facing and shaped to fit around the rotor. Alternatively, the magnetic field may be provided by two electromagnets.
Field electromagnets: Each electromagnet consists of a coil of many turns of copper wire wound on a soft iron core. The electromagnets are wound, mounted and shaped in such a way that opposite poles face each other and wrap around the rotor.
Brushes:The brushes are carbon blocks that maintain contact with the ends of the coils via the slip rings (AC) or the split-ring commutator (DC), and conduct electric current from the coils to the external circuit.

How DC generator works?

The commutator rotates with the loop of wire just as the slip rings do with the rotor of an AC generator. Each half of the commutator ring is called a commutator segment and is insulated from the other half. Each end of the rotating loop of wire is connected to a commutator segment. Two carbon brushes connected to the outside circuit rest against the rotating commutator. One brush conducts the current out of the generator, and the other brush feeds it in. The commutator is designed so that, no matter how the current in the loop alternates, the commutator segment containing the outward-going current is always against the "out" brush at the proper time. The armature in a large DC generator has many coils of wire and commutator segments. Because of the commutator, engineers have found it necessary to have the armature serve as the rotor(the rotating part of an apparatus) and the field structure as the stator (a stationary portion enclosing rotating parts)



  • Digg
  • Del.icio.us
  • StumbleUpon
  • Reddit
  • RSS
Read Comments

Parts Of The Submarine Cables




Parts of the Submarine Cables





 this type of cables are called the submarine cables. they are used in many uses like connecting the power to the rigs, islands, and Wind Turbines located in the water. the fiber optic cable assembled with the cable is used to transfer data between the two stations and sometimes the communication companies rent the line for their own uses

 




 



make  visit  to


 


  • Digg
  • Del.icio.us
  • StumbleUpon
  • Reddit
  • RSS
Read Comments

How to Choose PLC ?

How toChoose   (PLC) ?

selected PLC should satisfy many factors like:
 
-PLC should have sufficient number of digital inputs
-PLC should have sufficient number of digital outputs
-PLC should have sufficient number of analog inputs (if it requires)
-PLC should have sufficient number of analog outputs (if it requires)
-PLC should satisfy technical requirements like including: on delay retentive timer, internal clock, high speed counter, PID, … etc.
-In future if the system will be upgrade, PLC should have sufficient spare number of unused points or adding extension module is available
-if SCADA system or HMI will be added, PLC should be compatible with this system
-Price of PLC, software and programming cable
-if SCADA system HMI will not be added and low price is required, smart relay may be used instead of PLC
-if the customer need to receive the control system as fast as possible, it is preferable to use PLC brand which the programmer have last experience in it
 
 

 

  • Digg
  • Del.icio.us
  • StumbleUpon
  • Reddit
  • RSS
Read Comments

Main Parts Of Distribution Transformers

Main Parts Of  Distribution  Transformers



 

  • Digg
  • Del.icio.us
  • StumbleUpon
  • Reddit
  • RSS
Read Comments