Siemens SINUMERIK 840D sl Manual page 51

Requirements of DC power supplies
Danger of death caused by unsafe power supply
The DC power supply must be implemented as a circuit of Category PELV/DVC A according
to EN 61800-5-1.
Inadequately fused supply cables can be life-threatening
In the case of supply lines > 10 m, protectors must be installed at the device input in order
to protect against lightning (surge).
The DC power supply must be connected to the ground/shield of the NCU for EMC and/or
functional reasons. For EMC reasons, this connection should only be made at one point. As
a rule, the connection is provided as standard in the S7-300 I/Os. In exceptional
circumstances when this is not the case, the ground connection should be made on the
grounding rail of the control cabinet; please also refer to /EMC/EMC Installation Guide.
Table 7-4
Rated voltage
Non-periodic overvoltages
Transient voltage interruptions
Additional references
Recommended power supply units and tables for calculating the current drawn for SINAMICS
S120 module lineups can be found in chapter "Control cabinet design and EMC Booksize" of
the "SINAMICS S120 Booksize power units" manual.
NCU 7x0.3 PN, NCU 7x0.3B PN
Manual, 06/2014, 6FC5397-1EP40-5BA1
DANGER
WARNING
DC power supply requirements in accordance with EN 61131-2
Voltage range (average value)
Voltage ripple peak-to-peak
Booting time at POWER ON
Duration of overvoltage
Recovery time
Events per hour
Outage time
Recovery time
Events per hour
24 V DC
20.4 V DC to 28.8 V DC
5% (unfiltered 6-pulse rectification)
Any
≤ 35 V
≤ 500 ms
≥ 50 s
≤ 10
≤ 3 ms
≥ 10 s
≤ 10
Connecting
7.4 Power supply
51