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

9.4

Power supply

9.4.1

Requirements for the power supply

External 24 V power supply
Power is supplied to the Control Unit by an external 24 V power supply (e.g., SITOP). The
following power consumption values for the Control Units provide a configuration basis for
calculating the 24 V DC power supply.
Table 9-1
Parameters
Typ. power consumption
Max. power consumption
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
The DC power supply is always referenced to ground and may not be generated by an
autotransformer.
Final user interfaces are powered via a DC power supply with protective separation per
EN 1800-5-1.
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 Control Unit 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.
NCU
Manual, 03/2010, 6FC5397-0AP10-3BA0
Input voltage specification
1)
2)
DANGER
Values
2.0 A
8.5 A
Connecting
9.4 Power supply
65