Siemens S5-135U/155U System Manual page 94

Central Controllers and Expansion Units Power Supply Units
Removing the
Power Supply Unit
When to Remove
You must remove the power supply unit if you:
the PSU
Caution
!
Power supply units may only be removed when power is switched off.
If 230 V I/O modules are fitted, you must ensure before removing the power
supply unit that the subrack is grounded when the PSU is removed, or the
230 V supply for these modules is switched off.
When the power supply unit is removed, the connection between backup
battery and backplane bus remains; this ensures backup of the user program.
How to Remove Proceed according to the following steps to remove the power supply unit:
the PSU
4-28
change the jumper settings
send the power supply unit in for repair.
Action
Step
1 Switch the Power switch off
(standby On/Off).
2 Disconnect the power supply unit form the AC line voltage.
3 Detach the connections of all leads from the front terminals.
4 Important p
Before pulling out the PSU, wait at least 8 minutes after switching off the
power so that the electrolytic capacitors can discharge.
!
5 Slacken the fixing screws on the left and right of the PSU.
Pull the PSU out.
6
There are grips to pull it out under the unlock fan openings.
System Manual
C79000-G8576-C199-06