Siemens Simatic RTU303xC Series Operating Instructions Manual page 85

Depending on the type of power supply, follow the steps below:
Supply of the RTU only via external power supply
Turn on the external power supply.
The RTU starts up.
Supply of the RTU only via battery modules
NOTICE
Do not place the battery holders on a conductive surface.
Never place the battery holders on an electrically conductive surface (e.g. the outer
housing).
The battery contacts can establish a short-circuit connection in the battery via a conductive
surface causing the battery to be destroyed.
Only use undamaged batteries
Use only undamaged batteries. A battery with a damaged casing can cause a short-circuit
through the metal clips.
Note
Battery types
Only use the batteries described in the Appendix of the manual. Correct battery operation is
only ensured with these battery types.
If you use two battery modules or one battery module with battery expansion modules, start
with the first battery module.
For information on the location and labeling of the battery modules and battery expansion
modules, refer to the appendix Battery module and battery expansion module (Page 351).
1. Take the battery holder out of the battery module.
2. Insert the batteries in the battery holder.
3. Put the battery holder in the battery module.
4. Plug the connector of the battery holder in the socket X10 BATTERY of the battery
module.
If applicable, perform the same steps for the battery expansion modules and for the second
battery module including its expansion modules.
RTU303xC
Operating Instructions, 06/2019, C79000-G8976-C382-06
Connecting up, installation, commissioning
3.9 Commissioning and starting up the RTU
85