Siemens SINAMICS S120 Function Manual page 510

Function modules
8.9 Master/slave function for Active Infeed
Features
● The "master/slave" function only works in conjunction with Active Line Modules.
● One Active Line Module is the master and up to three others are slaves.
● If the master fails, a slave ALM takes on the role of the master.
● The redundant infeeds can continue functioning normally even if one infeed train has
failed.
● Electrical isolation between the infeed trains is needed on the line side to prevent
circulating currents caused by non-synchronous pulsing patterns.
● The entire infeed system supplies a joint DC busbar (DC link).
● Since the Active Line Module cannot detect whether the DC link is disconnected or a DC-
link fuse has blown, an additional circuit to monitor these states must be installed (DC
breaker checkback function and fuse signaling contacts).
● The higher-level controller communicates with the CUs and Active Line Modules via
PROFIBUS/PROFINET or analog data. If a higher-level controller is not to be used, the
control signals must be hard-wired (e.g. via TM31).
● Infeed trains with different outputs can be combined.
510
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
Drive functions