BECKHOFF AL2000 Application - Manual (Page 31)

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Step 5: Amplifier sizing
For most servocontrollers the duration of the peakcurrent is limited from 0.25 to several seconds. If the current
exceeds the continous current during a period, longer than this specified time, the required continous current
must be raised to this higher level. So check whether in long periods the required current is over the continuous
current. Choose a servocontroller which can deliver the required I
cont
and I
peak
.
Here, from the specified K
rms
and the calculated F
rms
we obtain
The maximum force during the cycle is 630N, so the servo-amplifier has to generate a maximum current
Since the periods of I>I
cont
are no longer than 5 seconds the AX2006 is fullfilling the requirements.
For braking heavy loads from high speeds (for example 100 kg at 4 m/s) the motor feeds back the electrical
power into the servo-amplifier. Most of it is dissipated in a braking resistor. Of course this resistor should be of
sufficient power, especially when such situations occur frequently (for instance in short repeated moves).