Maintenance
7-4 AutomationSystem S7-400 Hardwareand Installation
A5E00850741-01
7.2 Replacing a Power Supply Module
Slot Numbering
If you have provided the modules in your system with slot numbering, you must
remove the number from the old module when replacing it and apply the number to
the new module.

Removing the Module (Ignore Steps 1 and 2 When Using Redundant Power

Supply Modules)

1. Setthe CPU mode switch to STOP.
When you replace the power supply module in an ER, the CR may remain in the
RUN state, depending on CPU programming. Youcan back up the data in the
ER via the EXT.BATT.socket of the receive IM.
2. Ifyou wish to back up the data in the CPU, you can use the EXT. BATT.socket
of the CPU (see Reference Manual, Chapter 1).
3. Setthe standby switch of the power supply module to (0 V output voltages).
4. Setthe line disconnector to OFF.
5. Removethe cover.
6. Removethe backup battery/batteries if applicable.
7. Disconnectthe power supply connector from the power supply module.
8. Loosenthe mounting screws of the module.
9. Swingthe module out.
Installing a New Module
1. Checkthe voltage selector switch.
2. Attachthe new module of the same type and swing it downwards.
3. Screwthe module on.
4. Checkthat the power disconnector is set to OFF and the standby switch to .
5. Plugin the power supply connector at the power supply module.
6. Insertthe backup battery/batteries, if applicable.
7. Closethe cover.
8. Setthe power disconnector to ON.
9. Setthe standby switch of the power supply module to I (output voltages at rated
value).
10.Set the CPU mode switch to RUN if applicable.
How the S7-400 Behaves after Exchanging Modules
If an error occurs after replacing a module, you can read out the cause of the error
from the diagnostic buffer.