Requirements For The Power Supply - Siemens SINUMERIK 840D sl Equipment Manual

7.5.2

Requirements for the power supply

External 24 V power supply
Power is supplied to the NCU by an external 24 V power supply (e.g.: SITOP). The following
power consumption values for an NCU provide a configuration basis for calculating the 24 V DC
power supply.
Table 7-3
NCU 710.3B PN
NCU 720.3B PN
NCU 730.3B PN (PLC 317)
NCU 730.3B PN (PLC 319)
NCU only (processor, memory, etc.)
1)
NCU with full load at all outputs (digital outputs, USB, DRIVE-CLiQ, PROFIBUS DP etc.)
2)
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
NCU 7x0.3B PN
Equipment Manual, 10/2020, 6FC5397-1EP40-6BA1
Input voltage specification
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
Typ. current consumption
0.9 A
0.94 A
1 A
1.25 A
24 V DC
20.4 V DC to 28.8 V DC
5% (unfiltered 6-pulse rectification)
Any
≤ 35 V
≤ 500 ms
Connecting
7.5 Power supply
Max. power consumption
1)
11.7 A
14.6 A
14.6 A
15 A
2)
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