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Difference between two quadrant and four quadrant energy meters. ..

Discussion in 'Electronic Design' started by Jaspreet, Nov 23, 2003.

  1. Jaspreet

    Jaspreet Guest

    Hi,

    What i want to know:
    I just want to ask a very basic question.
    I read it many times that four quadrant energy meters are
    bi-directional and two quadrant energy meters are uni-directions (or
    ratcheted). I want to know what are these four quadrants ( preferebly
    on cartesian chart shown below)and how does a meter operated in these
    four quadrants?

    4 Quadrant and 2 quadrant action of a motor is described below. But a
    meter can't act as a generator. Then why people describe meters as two
    quadrant meters and four quadrant meters.

    ============================================================================
    What i know :
    In motor/generator operation, the term two quadrant/ four quadrant
    comes from the speed vs. torque chart. It is normally a Cartesian
    coordinate chart where the +/- speed is the x axis and the torque is
    in the +/- y axis. See chart [hopefully intact]

    t|
    II o| I
    r|
    q| speed
    ------------u--------------
    e|
    III | IV
    |
    |


    Two quadrant means that the motor drive operates between quandrant I
    and III. These types of motor can not stop instantly and reverse
    directions.

    Four quadrant motor drive operate in all four quadrants. These types
    of drives can do both "motoring" (I & III) and generating (II & IV).
    The motor acts as a generator when its inertia is continues to rotate
    it one way when it is in reverse rotation.


    -----------------------------------------------------------------

    Please explain it in cartesian coardinates, if possible.


    Regards,
    Jaspreet
     
  2. The main difference being that 4 quadrants allows a
    motor to be generator. This may be usefull in a lift
    when a heavy mass has to be lowered. The braking energy
    could be used to generate electricity.

    Rene
     
  3. The quadrants have to do with the possible signs on torque and
    rotation rate. If the torque is positive and the rotation rate is
    positive, that is quadrant 1. If the torque and rotation rate are
    both negative, that is quadrant 3. In both of these cases, the
    product of torque and rotation rate produces a positive value,
    indicating power delivery to the shaft. In quadrants 2 and 4, torque
    and rotation rate have opposite signs, so their product produces a
    negative value of power, indicating receipt of power from the shaft
    and generation of electrical power instead of consumption.

    A 4 quadrant drive can not only deliver power to the motor in for
    either polarity of voltage, it can also accept power from the motor
    for either polarity of voltage, and push this power back into the
    power lines.
     
  4. GPG

    GPG Guest

    Substitute V and I for axes. In two Q the W is negative.
     
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