
Functions
7.10 Safe Torque Off (STO) safety function
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
219
7.10.5
Forced dormant error detection
To fulfill the requirements of standards EN 954-1, ISO 13849-1 and IEC 61508 regarding
timely error detection, the inverter must regularly test its safety-relevant circuits to ensure
that they function correctly - this must be performed at least once every year.
Forced dormant error detection (test stop)
After the power supply has been connected, the inverter checks its circuits to switch-off the
torque each time the STO function is selected.
The inverter monitors the regular test of its safety-relevant circuits using a time module.
7
U
3RZHU21
5HVHW
672
U
$
S
Figure 7-27 Forced dormant error detection monitoring
r9660 contains the remaining time until the monitoring responds. The inverter signals Alarm
A01699 after the monitoring time expires.
You define the monitoring time while commissioning the system depending on your particular
application.
Examples for the times when forced dormant error detection is performed:
● When the drives are at a standstill after the system has been switched on.
● When the protective door is opened.
● At defined intervals (e.g. every 8 hours).
● In automatic mode (time and event dependent).
If alarm A01699 signals that the monitoring time has expired, then you must initiate the
forced dormant error detection at the next opportunity. These alarms do not affect the
operation of your machine.