Assignment planning
3.6 Configuring the electrical structure
ET 200M
50 Operating Instructions, 04/2022, EWA-4NEB7806006-09
Rules on the Power Consumption and Power Loss of an ET 200M
For their operation, the S7-300 modules use the necessary power from the backplane bus as
well as, if necessary, from an external load power supply.
• The current consumption of all signal modules from the backplane bus must not exceed
the electrical output that the IM 153-x can supply to the backplane bus.
• The PS 307 power supply is dependent on the current consumption from the 24 V load
power supply; this is the result of the total of the current consumption of the signal
modules and all other connected loads.
• The power loss of all the components in a cabinet must not exceed the maximum thermal
rating of the cabinet.
Tip: When establishing the required dimensions of the cabinet, ensure that the
temperature inside the cabinet does not exceed the permissible 60°C even where external
temperatures are high
You will find the values for the power consumption and power loss of a module under the
technical specifications of the relevant modules.
3.6.2 Operating the ET 200M with process I/O on a grounded supply
The following gives information on the overall configuration of an ET 200M to a grounded
supply (TN-S-network). The topics covered here are:
• Switch-off organs, short-circuit and overload protection in accordance with DIN VDE 0100
and DIN VDE 0113
• Load power supplies and load circuits
Grounded supply
With grounded supplies the neutral line of the network is grounded. A simple contact to earth
between a live cable and ground or a grounded part of the unit triggers the safety organs.
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