The "Safe Torque Off" safety function terminates the essential service mode.
WARNING
Unexpected exiting of the essential service mode by selecting "Safe Torque Off"
An active Safe Torque Off (STO) safety function switches the motor off, thus terminating the
essential service mode. The termination of essential service mode can cause severe injury or
death, e.g. for the failure of a flue gas extraction.
● Prevent the STO safety function from being selected in essential service mode by
controlling the converter appropriately.
● Take the unintentional selection of the STO safety function into account in the risk analysis
of the system.
Setpoint during active essential service mode
The converter changes the speed setpoint to the ESM setpoint source.
P3881 determines the ESM setpoint source. If you have defined an analog input as setpoint
source using p3881, the converter can switch over to setpoint p3882 in case of wire breakage.
Reaction to faults during active essential service mode
In "essential service mode", the converter does not switch off the motor when faults develop,
but rather reacts differently depending on the fault type:
● The converter ignores faults, which do not directly result in the destruction of the converter
or the motor.
● Faults with the reaction "OFF2" switch the motor off immediately.
In this case, the converter attempts to automatically acknowledge the faults using the
automatic restart function.
● For faults that cannot be acknowledged, it is possible to switch over the motor to line
operation using the bypass function.
Automatic restart during active essential service mode
The converter ignores the settings in p1206 (faults without automatic restart) and works with the
setting "restart after a fault with further start attempts" (p1210 = 6).
The converter carries out the maximum number of restart attempts set in p1211 corresponding
to the settings in p1212 and p1213. The converter outputs fault F07320 if the restart attempts
are not successful.
Interaction for bypass and essential service mode
● If the bypass mode is active when the essential service mode is activated, the converter
changes to converter mode. This ensures that the converter uses the ESM setpoint source.
● If faults are still present after the number of start attempts parameterized in p1211, then the
converter goes into a fault condition with F07320. In this case, there is an option of switching
over to bypass operation and then directly connecting the motor to the line supply.
Advanced commissioning
6.9 Drive availability
SINAMICS G120X converter
430
Operating Instructions, 06/2019, FW V1.01, A5E44751209B AC
