Connect with us

Explain the principle of operation of a synchronous generator with the aid of calculations.

Discussion in 'Electronics Homework Help' started by evilsanta, Apr 25, 2014.

Scroll to continue with content
  1. evilsanta

    evilsanta

    18
    0
    Mar 9, 2014
    Anyone any ideas on what I should be including in my answer? Its a bit of an odd question but Im not sure as to what to do for it. Any advice would be great, book references or web addresses anything at all as to what I should include.

    Thanks in advance
     
  2. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    Somewhere I have a book 'Aternating current machines' by Kay. I can understand most of it.

    Edit or Say
    Edit2 Alternating Current Machines by M.G.Say 1976/1977
    ISBN 0 273 36197 X
     
    Last edited: Apr 25, 2014
  3. evilsanta

    evilsanta

    18
    0
    Mar 9, 2014
    Explain the principle of operation of a synchronous generator with the aid of calculations.

    A synchronous generator converts mechanical energy to Electrical energy. The source of which creates the mechanical energy may be a steam engine, water falling through a waterwheel, a wind turbine, a hand crank or via compressed air.


    A synchronous generator has 2 main parts:


    1) Stator

    2) Rotor


    The Rotor is the rotating part whereas the Stator is the stationary part, hence where they get their names from.


    • Rotor has north and south poles protruded on it, in the case of salient poles, on which Laminations are used to reduce Eddy losses. The north and south poles of the rotor are wrapped with windings, the number of poles will always be even and dependent on the speed of the generator.

    • A separate DC supply is provided to the rotor with the help of slip rings and brushes and the current is passed to windings on the rotor. The rotor is attached to the shaft which makes the rotor rotate. As winding carrying current is under permanent magnet poles of rotor it will itself creates its own magnetic field

    • Stator is the stationary part . it is the section made of steel plates combined together with windings on it at 120 degree intervals to balance it out.

    • Now as the rotor rotates its magnetic field will cut the windings of the Stator and this in turn will cause an AC voltage to be induced in the Stator windings and an AC current is drawn.

    A synchronous generator operates on the amount of poles wound within its stator. The more poles in the stator equates to a smaller rev/min. For example a 2 pole generator would run at maximum of 3000r/min whereas a 4 pole generator would only run at 1500r/min. This is done with the equation F=NsP to find the speed at which the motor runs at. The rotation of the shaft is synchronized with the frequency of the supply current, which means the rotation period is exactly equal to the number of AC cycles.

    I would also use Faradays law to help explain the principle of operation with calculations. Faradays law means that the amount of voltage created is equal to the change in magnetic flux divided by the change in time. The bigger the change you have in the magnetic field, the greater amount of voltage.

    Fleming's right hand rule (for generators) shows the direction of induced current when a conductor moves in a magnetic field. No current is induced if the motion of the conductor is in line with the field, going either direction, and the same can be said if it runs parallel to current.

    The right hand is held with the thumb, first finger and second finger mutually perpendicular to each other (at right angles), as shown in the diagram .

    • The Thumb represents the direction of Motion of the conductor.
    • The First finger represents the direction of the Field. (north to south)
    The Second finger represents the direction of the induced or generated Current (the direction of the induced current will be the direction of conventional current, from positive to negative.

    This is the answer ive came up with so far, any criticisms or improvements I can make to it?
     
  4. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    Quite a good exposition.
    The laminations are not steel, this term is normally used for an iron/carbon alloy or stainless steel. The laminations are iron/silicon (4%) with minimum carbon. The silicon iron has low magnetic loss and a high electrical resistance to minimise eddy currents.

    The DC energisation can be varied depending on the use of the machine. If the energisation is low, the generator appears as an inductance across the mains. If the energisation is high, then the machine will have a capacitive component. In some cases, the machine may be run without a load to compensate for other machines which are inductive.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-