Copley STO (Safe Torque Off) per IEC 61800 SIL 3 ISO 13849-1 PL

The Copley certified STO safety circuit is redundant comprising of fault tolerant hardware that will disconnect the output stage from the motor for safety. It is to be used with external safety circuits and can help reduce system costs by reducing the number of external contactors between the drive and motor.

For safety calculations Copley provides the required parameters.

Example:

IEC 61508: 2010
SIL Safety Integrity Level 3
HFT Hardware Fault Tolerance 2
PFH Probability of Failure per Hour 5.1E-9
PFD Probability of Dangerous Failure upon Demand 4.5E-4
ISO 13849-1: 2006
PL Performance Level d Cat 3
CCF Common Cause Failure 80
DC Diagnostic Coverage 71%
MTTFd Mean Time to Failure 100 years

[zjoozjoo]

Too bad for the poor sound... use tie mic's please

[davidbernardi]

If we have multiple drives, do we need a separate safety relay for each drive, or can we power the STO circuits of all the drives from the one set of contacts on one relay?