Siemens SINAMICS G120C USS/MB Operating Instructions Manual page 102

Installing
4.9 Connecting the interfaces for the inverter control
Note
Malfunction caused by incorrect switching states as the result of diagnostic flows in the off
state (logical state "0")
In contrast to mechanical switching contacts, e.g. emergency stop switches, diagnostic flows
can also flow with semiconductor switches in the off state. If interconnection with digital inputs
is faulty, the diagnostic flows can lead to incorrect switching states and thus to a malfunction
of the drive.
● Observe the conditions for digital inputs and digital outputs specified in the relevant
manufacturers documentation.
● Check the conditions of the digital inputs and digital outputs in regard to the flows in off
state. If applicable, connect the digital inputs with suitably dimensioned, external resistors
to protect against the reference potential of the digital inputs.
NOTICE
Overvoltages for long signal cables
Using long cables at the inverter's digital inputs and 24 V power supply can lead to overvoltage
during switching operations. Overvoltages can damage the inverter.
● If you use cables of more than 30 m at the digital inputs and 24 V power supply, connect
Table 4-9
Solid or finely stran‐
Wiring the terminal strip to ensure EMC
● If you use shielded cables, then you must connect the shield to the mounting plate of the
control cabinet or with the shield support of the inverter through a good electrical connection
and a large surface area.
● Use the shield connection plate of the inverter as strain relief.
Further information about EMC-compliant wiring is available in the Internet:EMC installation
guideline (http://support.automation.siemens.com/WW/view/en/60612658)
102
an overvoltage protection element between the terminal and the associated reference
potential.
We recommend using the Weidmüller overvoltage protection terminal with designation
MCZ OVP TAZ DIODE 24VDC.
Permissible cables and wiring options
Flexible conductor
ded cable with non-insulated
Flexible conductor
with non-insulated
end sleeve end sleeve
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34263257B AF
Two finely stranded cables with
the same cross-section with par‐
tially insulated twin end sleeves
SINAMICS G120C converter