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08.02
02.99
08.04
2.2.3
Regenerative feedback protection when the motor brakes
General
If SIMODRIVE POSMO A is used in a system with low mechanical fric-
information on
tion, then the electrical energy, regenerated when braking, can influ-
regenerative
ence the load power supply. In cases such as these, regenerative feed-
feedback
back protection must be used.
protection
The regenerative feedback protection is dependent on the following:
S
S
S
S
S
S
Braking energy
Under the specified conditions, the following typical braking energy per
drive is obtained:
S
S
The effective total moment of inertia and the braking energy have a
linear interrelationship, i.e. for twice the moment of inertia, twice the
braking energy is generated when the motor brakes.
Rules when using
The following rules must be observed for regenerative feedback protection:
regenerative
S
feedback
protection
S
E Siemens AG 2013 All Rights Reserved
SIMODRIVE POSMO A User Manual (POS1) – 08/2013 Edition
The coincidence factor on the line–up of POSMO A drives
The number of positioning motors operated on one line
The degree of efficiency of the mechanical system
The friction
The moments of inertia
The regenerative energy of a drive is calculated as follows
(without taking into account the losses):
S J S ω
1
2
W =
/
2
W:
Braking energy [Ws = (kgm
J:
Moment of inertia [kgm
ω:
Angular frequency = (2 S π S n) / 60
Conditions
– Braking from rated speed in S3 duty
– Effective overall moment of inertia = 1 motor moment of inertia
Braking energy (in consideration of typically arising losses)
– 1.0 Ws
––> SIMODRIVE POSMO A – 75 W
– 2.5 Ws
––> SIMODRIVE POSMO A – 300 W
Regenerative feedback protection must be used when using a
clocked load power supply (e.g. SITOP power).
If the regenerative feedback energy is unknown, then regenerative
feedback protection should always be used.
2 Installing and Connecting–Up
2.2 Electrical system requirements
2
2
/s
)]
2
]
[1/s]
with n [rpm]
2
2-37
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