2
2.2 Electrical system requirements
2-40
E Siemens AG 2013 All Rights Reserved
SIMODRIVE POSMO A User Manual (POS1) – 08/2013 Edition
Depending on the type of power supply, the following possibilities are
available to provide regenerative feedback protection when the motors
brake:
Non–regulated 24 V power supply (transformer, rectifier)
The regenerative feedback protection depends on the following factors:
S Effective total moment of inertia
S Coincidence factor
S Power supply used (output rating)
Regulated 24 V power supply (SITOP power)
S Regenerative feedback protection with diode and capacitor
An example is shown in Fig. 2-11 where up to 3 drives can be oper-
ated under the following conditions:
– Effective overall moment of inertia = 1 motor moment of inertia
– Coincidence factor = 1
– Braking from rated speed in S3 duty
SITOP power
Diode (adapt the current load capacity
to SITOP, if required, use a heatsink)
Elko
15000 μF/50 V
SIMODRIVE
POSMO A, 1
SIMODRIVE
POSMO A, 3
to the
remaining
system
24 V
M
L+
M
Fig. 2-11 Example: Regenerative feedback protection with diode and
capacitor
S Regenerative feedback protection with Power Management Module
24 V DC (DC PMM/24V)
1 DC–PMM/24V can accept a braking power of 10 W.
Example:
Braking 5 motors, that individually have a rated current of 5 A and a
regenerative feedback energy of 3 Ws per braking operation, once
simultaneously, then a DC–PMM/24V is sufficient for this single
braking operation.
However, in this case, it is not possible to continuously brake the
motors per second or over a longer time period, as in this case, the
maximum permissible continuous power of 10 W would be ex-
ceeded and the I
2
t monitoring would respond. The unit goes into a
”fault” condition and can only be restarted after a ”reset”.
Regenerative
feedback
protection for
24 V supply
(75 W motor)
2 Installing and Connecting–Up
02.9906.05
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