2.6 Suggestions regarding circuit breaker and fuse If the driver is provided with a residual-current circuit breaker, to prevent malfunction of the circuit breaker, do select a model with the induced current of above 200mA and the actuation time of above 0.1s. For fuse, a fast-acting fuse shall be used, and its rated current shall be around 1.5 times the driver capacity. It is highly recommended:to use a UL/CSA-accepted fuse and circuit breaker. 2.7 Braking resistor selection When the motor has an output torque in opposite direction of its rotating speed, energy will be transferred from the load end back to the driver.
The energy will be charged into the bus capacitor to increase the bus voltage inside the driver; the amount of energy so charged depends on the motor rotor and the load inertia. If the system has low inertia, the energy transferred back may be fully absorbed by the capacitor inside of the driver; if the system has high inertia and the energy transferred back exceeds the absorbing capacity of the capacitor, excessive rise of the voltage may cause shutdown or even damage of the driver. For this reason, when the voltage rises to a certain value, the energy transferred back needs to be consumed by a braking resistor.
Table 2-1 below gives common rotor inertia of the SER series servo motor and absorbing capacity of the capacitor inside of the EA190 driver, as well as the calculating formula of the recoverable energy . Table 2-1 Common rotor inertia of the SER/SES series servo motors and recoverable energy-absorbing capacity of their capacitors 2.7.1 Built-in braking resistor The EA190 series driver contains a braking resistor, applicable to circumstances of average load inertia. Table 2-2 shows specifications of the built-in braking resistor for EA190 series.
Table 2-2 Built-in braking resistor of EA190 driver and the minimum allowable resistance of an external braking resistor 2.7.2 Resistance capacity calculation of external braking resistor When the recovering capacity exceeds the recovering capacity of the built-in braking resistor (say an Al017 warning occurs), an external braking resistor shall be used. According to the calculation formula of recoverable energy, if the total inertia of load is N multiples of the motor's rotor inertia, then the recoverable energy of the motor braking from the rated speed to 0 is N*Eo, and the actuation cycle is T(s).
Power of the braking resistor = 16 Technical Manual for EA190 Series Servo Driver V100 Driver model Motor Rotor inertia J (x10-4kgm2) Recoverable energy from the rated speed without load to stop Eo (J) Maximum amount of recoverable energy to be absorbed by the capacitor Ec (J) EA190□-0R9-1B SES04-005-30-2□AY 0.02 0.1 9.5 EA190□-1R6-1B SES04-0R1-30-2□AY 0.04 0.2 9.5 SES06-0R2-30-2□BY 0.29 1.43 9.5 EA190□-2R5-1B SES06-0R4-30-2□BY 0.58 2.87 19 EA190□-4R8-2B SES08-0R7-30-2□BY 1.56 7.71 20.2 EA190□-6R2-2B SER13-1R0-20-2□BY 8.71 19.1 20.2 ● Calculation formula for recoverable energy: Eo = J v2 /182 (J) v:
rpm, generally referring to the rated speed of the motor A servo motor with brake may be deemed to have the same rotor inertia as a servo motor without brake due to negligible difference in the rotor inertia. Driver model Specification of the built-in braking resistor Recovering capacity of the built-in braking resistor Allowable minimum resistance of external braking resistor Resistance (P8-10) Capacity (P8-11) EA190-0R9-1B None None None 50Ω EA190-1R6-1B None None None 50Ω EA190-2R5-1B None None None 50Ω EA190-4R8-2B 50Ω 100W 50W 50Ω EA190-6R2-2B 50Ω 100W 50W 50Ω