The TWX Motor Series with Integrated Drive, is compliant with the Safety Indistrial Level (SIL) 2 and 3.
What is the Safe Torque Off Safety Function?
Safe Torque Off is an important safety function integrated into TWX servo drive: it cuts off eMotor torque power to prevent unexpected start up, such as during maintenance or human presence.
How STO works?
It is controlled by two dedicated wires inside the power cord that carries a low voltage +24 V signal to the drive.
When at least one of the two signal are interrupted, tipically by operator pressing the safety button, STO is activated.
In this way, STO function is a fieldbus indipendent and redundant safety system(single fault tollerance).
What are the advantages of STO?
It is safer then a simple switch or disconnectors, reducing as well the total complexity, costs and space.
The main power can be kept so to mantain other safety and general machine functions.
STO activation generates a Drive Fault that has to be reset to restore normal condition, and a Canbus Alarm packet informs all other machines, master, or systems.
What is SIL 2 and SIL 3 level ?
STO with SIL 3 level allow a feedback signal so to ensure that the safety response is correct
Security notice
STO is not an emergency brake: after power cutoff to motor, it could still rotate as a result of system inertia and can be dangerous in case of suspended loads.
STO doesn’t actually shut down the source main power: if needed it has to be shutdown manually
Extra safety function using Auxiliary 24V Input *
As additional safety function, TWX motor allows to use the Auxiliary Input inside power cord (see pinout scheme) to perform by firmware a quick stop or a power disable action, choosing if action is performed on high or low Aux signal state. User must use the digital imput section of CockpitLT to set the behaviour (as default No action will be performed on aux input).
