Chapter 2 Installation and StorageRevision June 2010 2-11Servo Drive(kW) Servo Motor Rotor InertiaJ (× 10 -4kg.m2)Regenerative powerfrom empty load3000r/min to stopEo (joule)Max. regenerativepower ofcapacitanceEc(joule)0.4 ECMA-G21303
8.17 40.40 80.75 ECMA-G21306
8.41 41.59 14HighInertia1.0 ECMA-G21309
11.18 55.29 18Eo = J x wr2 /182 (joule) , Wr : r/minIf the load inertia is N × motor inertia, the regenerative power will be (N+1) x E0 whenservo motor brakes from 3000r/min to 0. Then, the regenerative resistor can dissipate:(N+1) x E0 - Ec (joule). If the time of repeat operation cycle is T sec, then the regenerativepower = 2 x ((N+1) x E0 - Ec) / T.The calculating procedure is as follows:Step Procedure Equation and Setting Method1Set the capacity ofregenerative resistor to themaximumChange the value of P1-53 to maximum2 Set the operation cycle T Input by the users3 Set motor speed wr Input by the users or read via P0-02 Drive StateDisplay4 Set load/motor inertia ratio N Input by the users or read via P0-02 Drive StateDisplay5 Calculate the max.regenerative power Eo Eo = J x wr2 /1826 Set the regenerative power Ecthat can be absorbed Refer to the table above7 Calculate the requiredregenerative power capacity 2 x (N+1) x Eo－Ec）/ TFor example:If we use 400W servo drive, the time of repeat operation cycle is T = 0.4 sec, max. motorspeed is 3000r/min, the load inertia = 7 × motor inertia, then the necessary the power ofregenerative resistor = 2 x ( (7+1) × 1.68 - 8) / 0.4 = 27.2W. If the calculation result issmaller than regenerative power, we recommend the users to use the built-in 60Wregenerative resistor. Usually the built-in regenerative resistor provided by ASDA-B2 seriescan meet the requirement of general application when the external load inertia is notexcessive.The users can see when the capacity of regenerative resistor is too small, the accumulatedpower will be larger and the temperature will also increase. The fault, ALE05 may occur ifthe temperature is over high. The following figure shows the actual operation ofregenerative resistor.
