Siemens SINAMICS G120 Operating Instructions Manual page 134

Installing
4.5 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.
In order to install the inverter in compliance with UL, you may only connect the DO 0 and DO 2
relay outputs of the Control Unit using copper wires approved for 75 °C.
Danger to life as a result of a hazardous voltage at the Control Unit
If the insulation is damaged on the lines that are connected to the terminals DO 0 and DO 2,
parts of the Control Unit may still be connected to the power supply. When connecting higher
voltages at terminals DO 0 and DO 2, there is a risk of electric shock when touching the
Control Unit.
● Only connect dangerous voltages using cables with double insulation at relay outputs
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 4-32
Solid or finely-stranded conduc‐
Cables with twin end sleeves are not permissible.
134
DANGER
DO 0 and DO 2 of the Control Unit.
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 cable and wiring options
tor
Finely-stranded conductor with
non-insulated conductor end
sleeve
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34257946B AE
Finely-stranded conductor with
partially insulated conductor end
sleeve
Converter with the CU230P-2 Control Units