When the output torque of servo motor in reverse direction of motor rotation speed, it indicates that there is a regenerative power returned from the load to the servo drive. This power will be transmitted into the capacitance of DC Bus and result in rising voltage. When the voltage has risen to some high voltage, the servo system needs to dissipate the extra energy by using a regenerative resistor. ASDA-A series servo drive provides a built-in regenerative resistor and the users also can connect to external regenerative resistor if more regenerative capacity is needed. When using an external regenerative resistor, connect it to P and C, and make sure the circuit between P and D is open. When using a built-in regenerative resistor, connect it to P and D, and ensure an open circuit between P and C. When the regenerative power exceeds the processing capacity of the servo drive, the fault, ALE05 may occur. At this time, please install an external regenerative resistor.