Smitec Cosmos 3152FA - Safety Integrated System; STO Function Description and Features; Safety Circuit Signal Definitions

COSMOS DRIVER SERIES 3000 - USE AND MAINTENANCE MANUAL
6 Safety integrated system
6.1 Description
The drivers COSMOS 3000 are equipped with a circuit for the STO function (Safe Torque Off). This function, if enabled,
allows the driver output to be disabled so that the driver cannot generate torque (or force, in case of linear motors). The
motor will actually stop in a time that can vary according to the inertia or to the load mechanical features; if it were
necessary to guarantee the stop of the mechanical device within a maximum time (example a load lifted by a pulley), it
will be necessary to implement this function with additional systems.
Features:
• the intervention of the STO function totally excludes the driver possibility to control the motor
• there is no way to disable the safety function, either intentionally or unintentionally
• the STO system is equipped with two independent inputs; a break-down of one of the two channels does not
interfere with the operation of the other channel
• the two inputs are powered by the same power supply, independent from any other power supplies of the
driver
• the STO system was designed to tolerate 1 hardware break-down
• the level of safety integrity is SIL2 with PFH (Probability of random Failure per Hour) < 1x10
-9
• The STO mission time is 20 years
• The required ambient conditions, the use and maintenance are the same as those required by the driver.
In order to guarantee the required safety degree, it is necessary to adequately control the signals, for example by using
a certified safety PLC.
6.2 Operation
6.2.1 Signals
The below chart shows the wiring and meaning of the signals.
Signal Description
24V Positive power supply for the safety circuit section
GND Mass of the power supply of the safety circuit section and reference for the inputs
EN1 Enable 1 signal, active at high logical level (24V = enabled, 0V = disabled)
EN2 Enable 2 signal, active at high logical level (24V = enabled, 0V = disabled)
FBK-FBK Potential free contact; open, in case of safety system failure
6.2.2 Electrical specifications
Mains voltage 24V -15% ÷ +20%, with a ripple with a peak value equal
to 5% of the rated value (extreme values equal to
respectively 19.2 and 30.0 V)
EN1 and EN2 inputs Type 1 and type 3 in accordance with IEC61131-2
standards
EN1 and EN2 limits V
IL
=5,0V max.; V
IH
= 15,0V min.
Admissible voltage EN1 e EN2 30V max.
Absorbed current EN1 e EN2 5.5 mA max. each
Admissible voltage FBK-FBK 30V max.
Admissible current FBK-FBK 500mA max.
Ver. 1.07 Pag. 52