15 
1.4 Selection of other accessories 
1.4.1 Selection of regenerative resistance 
When the servo motor is driven by the generator mode, the power returns to the servo amplifier side, 
which is called regenerative power. The regenerated power is absorbed by charging the smooth 
capacitor of the servo amplifier. After exceeding the rechargeable energy, the regenerative resistance is 
used to consume the regenerative power. 
 
The servo motor driven by regenerative (generator) mode is as follows: 
  The deceleration stop period during acceleration and deceleration operation; 
  Running vertically and axially; 
  When the external load drives the motor to rotate. 
 
Regenerative resistance connection terminals 
(1) Using built-in regenerative resistance, short P + and D terminals, P + and 
C are disconnected. 
(2) Use external regenerative resistance, connect regenerative resistance to P 
+ and C terminals, remove P + and D short wiring, P0-25 = power value, 
P0-26 = resistance value. 
Note: if software version U2-07 < 3700, the parameter P0-24 should be set. 
The value of 0 is for the built-in resistance to take effect, and the value of 1 is 
for the external resistance to take effect. 
The following table is the recommended specifications of external regenerative resistance for each type 
of motor. 
(Not less than this value) 
External regenerative 
resistance 
(Recommended 
resistance value) 
External regenerative 
resistance 
(Recommended power 
values) 
  
Note: 
(1) The smaller the resistance is, the faster the discharge will be, but the smaller the resistance is, the 
easier the breakdown resistance will be. Therefore, please close to the the lower limit but not be less 
than the lower limit when choosing the type. 
(2)  When  wiring, please  use high-temperature  flame-retardant  wire,  and  the  regenerative resistance 
surface can not contact with the wire.