Quadrant diagram of Speed-Torque Characteristics

• The speed is assumed to be positive if the direction of rotation is anticlockwise or in such a way to cause an ‘upward’ or forward motion of the drive. For reversible drive positive direction of the speed can be assumed arbitrarily either clockwise or anticlockwise.
  
  
• The motor torque is positive if it produces increase in speed in the positive sense. The load torque is assigned the positive sign when it is directed against the motor torque.
  
  
• Plot of speed torque characteristics of the load/ motor for all four quadrant of operation is known as quadrantal diagram.