Siemens SIRIUS 3RT2 Manual page 52

Mounting
7.4 Disassembly
③
④
⑤
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Press the screwdriver towards the contactor.
Push the interlock slide up with a screwdriver. It is not possible to unlock from below.
Pull the basic module and the two coupling modules toward you and away from the contactors.
SIRIUS 3RA28 function modules for mounting on 3RT2 contactors
Manual, 02/2019, A5E03656507620A/RS-AD/005