Siemens SINAMICS G120 Operating Instructions Manual page 197

Examples of how the safety functions can be applied
Table 5- 90
Description of problem
When the EMERGENCY STOP button is
pressed, a stationary motor must not start
unintentionally.
A central EMERGENCY STOP button is
designed to prevent more than one drive
from starting unintentionally.
A short-circuit and cable break occurring
when the motor holding brake is activated
are to be signaled.
Having opened a protective door, the
machine operator must enter the
hazardous zone around a machine and
run a conveyor belt at low speed.
When a protective door is opened, the
motor must be stationary.
Controlling the safety functions
The safety functions in the inverter can be controlled via fail-safe digital inputs as well as
over safe bus communication PROFIsafe via PROFIBUS or PROFINET in conjunction with a
fail-safe CPU.
Safe feedback signals from the inverter
When fail-safe functions are used, feedback is generally required as to whether or not the
drive is in a safe state.
With the SLS function, for example, this is the case if the inverter has decelerated the motor
to below the speed monitoring limit. This safe state is signaled by the inverter via fail-safe
channels. On the basis of this, a higher-level controller can trigger further actions (e.g.
enable a protective door).
Fail-safe feedback signals from the inverter are realized using PROFIsafe.
Monitoring the safety functions -passivation:
A fail-safe inverter permanently monitors its hardware and software as well as the timing of
the safety function as soon as it was activated. In the case of a fault, the inverter passivates
itself:
● The inverter initiates an STO, i.e. the motor is safely switched into a no-torque condition
● The inverter signals a fault
In the List Manual, under the inverter fault message, you will find information and instructions
as to what you must do in order to acknowledge the fault and to terminate the inverter
passivation.
CU240S and CU240E Control Units, FW 3.2
Operating Instructions, 03/2009, A5E02440075B AA
Application examples for safety functions
Suitable Solution
safety function
STO Control the inverter via terminals using
an Emergency-Stop button.
STO Evaluate the Emergency-Stop button in a
central control, control the inverter via
PROFIsafe.
SBC Connect the motor holding brake to the
optional 'Safe Brake Module' of the
inverter.
SLS Control the inverter via terminals using a
button to move the conveyor belt.
SS1 Activate the SS1 function in the inverter
and enable the protective door as soon
as the inverter signals back 'STO'.
Functions
5.12 Safety functions
197