Technical data

24
Integrated safety thanks to Safe Torque Off
TheMachineryDirectiveestablishesthesafety
requirements that all machines must conform
to before they can carry the CE mark and be
manufactured and sold within the European
Community.
In particular, all machine movements must
be monitored by a safety system capable of
intervening in an emergency to stop motors
and disconnect power until normal operating
conditions can be restored.
Safety systems must intervene effectively and
guarantee physical disconnection between motor
and power source. They must also be reliable, i.e.
never fail to function.
Standards EN 954-1 and EN 61508 regulate safety
system effectiveness and reliability respectively.
These standards assign two distinct value scales to
effectiveness and reliability (Category and Level),
ensuring that machine manufacturers design in
a degree of safety adequate to the needs of the
application.
In a conventional drive, to guarantee the effective
disconnection of the motor and the absence of
turning moment at its shaft, the safety system uses
remote power switch outside the drive to insulate
the motor electrically.
Bonfiglioli has integrated the Safe-Torque-Off
system (STO, EN61800-5-2) in Agile drives in
response to market demand to reduce the size of
control panels, minimise the number of operating
components, simplify control, and eliminate the
mechanical stress caused by the sudden application
of the brake while the shaft is still turning. In
an emergency this system disconnects the motor
in compliance with EN13849 and EN61508 SIL2,
without the need for external contactor.
Generic
drive
Power
supply
M
Conventional safety system
Machine control
Safety system implemented by an Agile drive
Power
supply
M
Machine control
Integrated functional safety
conforming to EN61508 level SIL 2
Integrated electrical safety
conforming to EN13849