EAV64334 06/2017 19
Safety Function (SF) Level Capability for Safety Function STO
Emergency Operations
Standard IEC 60204-1 introduces 2 emergency operations:
Emergency switching-off:
This function requires external switching components, and cannot be accomplished with drive based
functions such as safe torque-off (STO).
Emergency stop:
An emergency stop must operate in such a way that, when it is activated, the hazardous movement of
the machinery is stopped and the machine is unable to start under any circumstances, even after the
emergency stop is released.
An emergency stop shall function either as a stop category 0 or as a stop category 1.
Stop category 0 means that the power to the motor is turned off immediately. Stop category 0 is
equivalent to the safe torque-off (STO) function, as defined by standard EN 61800-5-2.
In addition to the requirements for stop (see 9.2.5.3 of IEC 60204-1), the emergency stop function has
the following requirements:
It shall override all other functions and operations in all modes.
This reset shall be possible only by a manual action at that location where the command has been
initiated. The reset of the command shall not restart the machinery but only permit restarting.
For the machine environment (IEC 60204-1 and machinery directive), when safety function STO is
used to manage an emergency stop category 0, the motor must not restart automatically when safety
function STO has been triggered and deactivated (with or without a power cycle).
If the drive configuration enable automatic machine restart after the safety function STO has been
deactivated, an additional safety module (such as Preventa module) is required.
If the use of an additional safety module is not possible, the drive control must be configured in 2
wires transition (tCC = 2C and tCt = trn) or 3 wires (tCC = 3C).
Limitations
Type Of Motor
The safety function STO can be used with all motors supported by the drive.
Prerequisites for Using Safety Functions
Following conditions have to be fulfilled for correct operation:
The motor size is adequate for the application and is not at the limit of its capacity.
The drive size has been correctly chosen for the supply mains, sequence, motor, and application and
is not at the limit of its capacity as stated in the catalog.
If required, the appropriate options are used.
Example: output filter.
The drive is correctly set up with the correct speed loop and torque characteristics for the application;
the reference frequency profile applied to the drive control loop is followed.
Disable Error Detection
When the safety function is used, the error code [Safety Function Error] SAFF cannot be disabled by the
function [Disable Error Detection] InH.
Configuration SIL
Safety Integrity Level according
to IEC 61-508
PL
Performance Level according
to ISO-13849
STO with and without Safety module
(such as Preventa module)
SIL3 PLe
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