Siemens SINAMICS SM150 - Protection Responses in an Emergency; VDC-Max Closed-Loop Control

8.5.3.4 Protection responses in an emergency
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Figure 8-8 Networked structures for safe shutdown in an emergency
The overview diagram shows how central components are networked. The DRIVE-CLiQ
connection between CX32 and PSA is considered secure because communication on the
DRIVE-CLiQ cable is monitored cyclically. With regard to contactor control for the circuit-
breaker, a two-channel bypass to the open circuits is provided for safety reasons. This ensures
that the circuit-breaker triggers for every system-internal fault. This means system errors on the
CU or the PSA trigger the circuit-breaker. A bypass to the circuit-breaker is also provided via a
fiber-optic ring if faults occur in other inverter systems.
The following time-coded signals are transmitted via the fiber-optic ring:
● Pulse inhibit
● Circuit-breaker OPEN
● Short-circuiter CLOSED
● Conduction-through of all IGCTs
8.5.3.5 Vdc-max closed-loop control
The vdc-max closed-loop control permits (restricted) braking operation of a drive with a diode
supply to the DC link. During braking operation, the machine supplies power back to the DC
link. Due to the configuration, however, a diode supply cannot supply this power back to the
line. The vdc controller controls the supply of power back from the machine to compensate for
losses from the drive system and prevent the DC link voltage from exceeding the maximum
value. This avoids any fault shutdown caused by braking ramps that have been set too short.
The drive stops controlled. The ramp-down times may increase as a result.
Operation
8.5 Functions
SINAMICS SM150 6SL3845-2NN41-8AD2
118 Operating Instructions Rev.201910281310 EXAMPLE