BONFIGLIOLI Agile Series, Application Manual Functional Safety

Page: 14 / 42

14 AGL-STOV0-01SV0-05
06/12
5 General Description of Safety Function
5.1 Integrated Safety Function
Electronic protection systems are integrated in the drive control system and perform
safety functions in order to minimize or eliminate hazards caused by functional errors
of machines.
The integrated safety functions replace time-consuming and expensive installation of
external safety components.
The safety function can be requested or triggered by an error.
In hazard areas, setup work or work for elimination or errors may be required where
the safety function is not to be activated by isolating protection devices such as
mains contactors or motor contactors. Here, the additional safety function may be
used. STO can be used as an alternative to mains or motor contactors, which can be
omitted dependent on the application.
The integrated safety functions reduce the risk of personal damage in hazard areas
and reduce installation requirements.
5.2 Functional Safety
The safety function of the control system must be ensured for normal, trouble-free
operating sates as well as in the case of an error. As a result of this requirement:
− The safety function must be checked in case errors are present. Possible methods
include: error tree analysis, FMEA, etc.) u. a.
5.3 Classification the safety requirement
The integrated safety function “Safe Torque Off” of the AGL frequency inverter meets
the following requirements according to EN 61800-5-2:
− up to safety integrity level SIL 2 according to DIN EN 61508 for STO
− up to performance level d according to EN 13849-1
− of category 3 according to EN ISO 13849-1
In the case of an error, thanks to the safety function STO, the frequency inverter
does not supply energy to the motor which would cause a revolution or torque (or a
movement or force in the case of a linear motor).
Characteristic for the classification mentioned above:
− If an error occurs, the safety function is maintained.
With a suitable external safety control device the function „Safe Stopp 1 (SS1 c)“
according to EN 61800-5-2 can be realized together with the AGL.
By using appropriate safety control devices, stop category 0 and stop category 1
according to EN 60204 can be achieved in the machine. For safety control devices,
please refer to chapter 10.
Stop category 0: Stop by immediate disconnection of energy supply to the machine
drive elements, i.e. uncontrolled stop.
Stop category 1: Controlled stop, where energy is still being supplied to the drive
elements of the machine to perform the stopping operation. Energy supply is stopped
only after the drive has come to a standstill.
Note that the drive may not stop immediately but coast to a standstill. If no mechani-
cal brake is installed, or a defective brake may involve a risk, further protective
measures (in example tumbler) are to be taken.