Power Supply And Potential Ratios; Power Supply (Selv/Pelv); Power Supply Of The Sensors And Actuators - Siemens SIMATIC ET 200SP HA System Manual

4.6

Power supply and potential ratios

4.6.1

Power supply (SELV/PELV)

Safe low voltage
Ensure that the supply and input voltages of the I/O system are generated safely separately
U
rated
Power supply according to the following standards:
• EN / IEC /UL 61010-2-201
This safe extra-low voltage with the required protection is called SELV (Safety Extra Low
Voltage)/PELV (Protective Extra Low Voltage).
or
• NEC Class 2, as in the National Electrical Code (r) (ANSI / NFPA 70)
If the device is connected to a redundant power supply (two separate power supplies), both
power supplies must meet these requirements.
All input voltages occurring on the I/O system must be limited to the maximum value of
U = 60 V DC. This involves, for example, the following voltage sources:
m
• Power supply to the interface module of the basic design
• Supply voltage on all Ex power modules
• Supply voltage for sensors and actuators (e.g. on SP HA Standard modules)
See the assembly instruction in the respective documentation of the component used.
For compliance with Namur recommendation NE21, EN / IEC 61131-2, use power supplies/
power packs with bridging of supply failures of at least 20 ms.
4.6.2

Power supply of the sensors and actuators

You must ensure that the supply of the sensors and the actuators at the base assembly is
supplied with safe extra-low-voltage.
Power supply (SELV/PELV) (Page 43)
Modules for devices in a hazardous area
System Manual, 04/2021, A5E50165138-AA
= 24 V DC ±20% ( ).
Plant planning
4.6 Power supply and potential ratios
43