Siemens SIMATIC ET 200SP System Manual page 235

Maintenance
12.1 Removing and inserting I/O modules/motor starters (hot swapping)
NOTICE
Risk of hazardous system states
If you remove and insert digital output modules with the load switched on or technology
modules with the supply voltage switched on, this can result in hazardous system states.
The ET 200SP distributed I/O system or the connected sensors may be damaged as a
result.
Therefore, a digital output module may only be inserted and removed when the load is
switched off and a technology module may only be inserted and removed when the supply
voltage is switched off.
NOTICE
Risk of hazardous system states
If you remove and insert the AI Energy Meter ST with the primary-side voltage switched on
at the current transformer, this can result in hazardous system states.
The ET 200SP distributed I/O system may be damaged as a result.
For this reason, remove and insert the AI Energy Meter ST only in the following cases:
• When measuring voltage is switched off on the primary side, or
• When a special current transformer terminal is used that short-circuits the secondary
Do not remove or insert the AI Energy Meter ST until you have removed this current
transformer terminal. With the special terminal, the process can continue because the
current transformer is isolated safely. However, the measuring voltage on the module at the
connections UL1-UL3 still needs to be isolated.
Risk of injury from automatic restart
Inserting a motor starter can result in dangerous system states. The motor starter can
restart again autonomously if an ON command is active.
This can result in serious injury caused by connected devices that are automatically started
up.
Withdraw and insert a motor starter only after disconnecting the load.
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side of the transformer when the module is removed
WARNING
Distributed I/O system
System Manual, 09/2019, A5E03576849-AJ