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Speed of a Cumulative Compound DC Motor

  1. May 6, 2012 #1
    I came across an equation for the Speed ω in Radians/seconds of a Cumulative Compound DC motor.

    ω= K(Vt-IA[RA+RF)/([itex]\Phi[/itex]P+[itex]\Phi[/itex]S)

    • How would we calculate K in this equation?
    • Shouldn't the Terminal Voltage Vt be replaced by Armature Voltage Ea?
    • I came across a lot of varying torque speed curves. WIll the curve be exponentially decaying or linear?
  2. jcsd
  3. May 6, 2012 #2


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    2017 Award

    Staff: Mentor

    Maybe you should explain your formula and the used variables, or at least give its source.
    My guess: K is some constant given by the geometry of the motor.

    I don't think that any of these curves are perfectly exponentially or linear. In addition, it might depend on the motor (e.g. how its internal friction depends on the angular velocity).
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