Rockwell Automation DC3RD Digital Regenerative DC Drive User Guide 1/4 - 2 HP, 115/230 VAC - Manual (Page 59)

Most non-regenerative, variable-speed DC drives control
current flow to a motor in one direction. The direction of
current flow is the same direction as the motor rotation.
Non-regenerative drives operate in Quadrant 1, and also in
Quadrant 3 if the drive is reversible (see Figure 13,
page 52). Motors must stop before reversing direction.
Unless dynamic braking is used, non-regenerative drives
cannot oppose an overhauling load, and cannot decelerate a
load faster than coasting to a lower speed.
Regenerative drives operate in two additional quadrants:
Quadrant 2 and Quadrant 4. In these quadrants, motor
torque is in the opposite direction of motor rotation.
Regenerative drives can reverse a motor without
contactors, switches, brake resistors, or inhibit plugs. They
can also control an overhauling load and decelerate a load
faster than it would take to coast to a lower speed.
51
Regenerative Drives
250-0285-rev1.qxd 4/26/00 9:36 AM Page 51