Defining the Commutator and Brush for a General DC Machine

The commutator allows current transfer between DC terminals or brushes and the rotor coils, providing the current to the system as a function of rotation. Due to the action of the commutator, the corresponding magnetic field has a fixed distribution with respect to the stator.

To define the commutator and brush pairs:

  1. To open the Commutator Data Properties window, double-click the Machine > Commutator entry in the project tree on the desktop. (You can also enter values in the Properties section of the desktop without opening a separate window.)
  2. Click the Commutator tab.
  3. Select Cylinder or Pancake Type as the Commutator Type.
    4. Note: When you place the mouse cursor over the commutator type, an outline of the commutator appears.
  4. For Cylinder commutators, do the following:
    1. Enter the Commutator Diameter.
    2. Enter the Commutator Length.
  5. For Pancake commutators, do the following:
    1. Enter the Outer Diameter.
    2. Enter the Inner Diameter.
  6. Enter the thickness of the insulation between two consecutive commutator segments in the Commutator Insulation field.
  7. Click the Brush tab.
  8. Enter the Brush Width.
  9. Enter the Brush Length.
  10. Enter the number of brush pairs when using a wave armature winding in the Brush Pairs field.
  11. Enter the angle of displacement from the neutral axis, in mechanical degrees, in the Brush Displacement field.
    12. Note: The brush displacement is positive for the counter-clockwise direction. For example, if the rotor turns clockwise and the brush displacement is also clockwise, then the angle is negative; if the rotor turns clockwise but the brush displacement is counter-clockwise, then the angle is positive.
  12. Enter the voltage drop across one brush pair in the Brush Drop field.
  13. Enter the mechanical pressure of the brushes as they press against the commutator in the Brush Press field.
  14. Enter the Frictional Coefficient of the brush.
    15. Note: If the Friction Loss field is used in the General window, the Brush Press and Frictional Coefficient fields will be hidden in the Commutator/Brush window. These fields are shown only when the Friction Loss field in the General window is set to zero.
  15. Click OK to close the Properties window.