Siemens SINAMICS S120 Manual page 129

Protective connection via the mounting plate
Alternative to the described methods with protective conductors, it is also possible to
establish the protective conductor connection of the electrical cabinet through the mounting
plate, assuming that all of the following conditions are satisfied. As a consequence, the
requirements placed on a protective conductor for an increased discharge current are
satisfied. The marked protective conductor connections of the devices are then not assigned.
Conditions
● Only permissible for modules with internal air cooling
● Use a bare metal mounting plate that is resistant to corrosion, e.g. galvanized with a
minimum thickness of 2 mm.
● Electrically conductive connection between the mounting plate and the electrical cabinet
corresponding to the specifications of the electrical cabinet manufacturer.
● All module fixing screws must be screwed-in with spring washer and washer - and then
tightened with the specified tightening torque. Equivalent screw fittings are permissible.
● At least one fixing screw of the module is designated as protective conductor connection
with the symbol
● The continuity of the protective conductor connection must be checked, e.g. according to
IEC 60204-1 Chapter 18.2.2 or IEC 60364-6 Chapter 6.4.3.2.
● Just like all power connections, the fixing screws of the modules are regularly re-
tightened with the specified tightening torques.
Note
• Observe the local installation regulations.
• In the case of equipment whose final destination is the USA or Canada, connection using
a protective conductor is mandatory.
Power Units in Booksize C/D-Type Format
Manual, 12/2018, 6SL3097-5AC20-0BP0
6.10 Protective connection and equipotential bonding
(IEC 60417–5019).
Cabinet design
127