When a fault, ALE05 (Regeneration Error) is detected on the servo drive, it indicates that regenerative power has returned from the load to the servo drive and it exceeds the processing capacity of the servo drive. This power will be transmitted into the capacitance of the DC Bus and result in rising voltage. When the voltage rises too high, the servo system needs to dissipate the extra energy by using a regenerative resistor. The ASDA-A2 series servo drive provides a built-in regenerative resistor which is equipped as standard. Users can also connect an external regenerative resistor if more regenerative capacity is needed. The following table shows the specifications of the servo drive's built-in regenerative resistor and the amount of regenerative power (average value) that it can process. ASDA-A2 220V Series ASDA-A2 400V Series Please pay close attention to the following notes when using a regenerative resistor. 1.Make sure the settings of resistance (parameter P1-52) and capacity (parameter P1-53) are set correctly. 2.When installing an external regenerative resistor, make sure that its resistance value is the same as the resistance of the built-in regenerative resistor. If combining multiple small-capacity regenerative resistors in parallel to increase the regenerative resistor capacity, make sure that the resistance value of the regenerative resistor complies with the specifications listed in the table above. 3.In general, when the amount of regenerative power (average value) that can be processed is used at or below the rated load ratio, the resistance temperature will increase to 120°C or higher (when regeneration occurs continuously). For safety reasons, forced air cooling is a good way to reduce the temperature of the regenerative resistors. We also recommend using regenerative resistors with thermal switches. As for the load characteristics of the regenerative resistors, please check with the manufacturer. 4.When using an external regenerative resistor, connect it to P and C, and make sure the circuit between P and D is open. We recommend using external regenerative resistors with resistance values that follow the table above (Specifications of Built-in Regenerative Resistors).