Relevant Failure Modes; Fault Exclusions; Operation Delays - ABB ACS880-07 User Manual

30 Option description and instructions
Diagram 4: ACS880-17/37 drives, frames nxR8i + nxR8i
E-stop
button
Auxiliary
safety
relay

Relevant failure modes


•
The main contactor does not open when requested. (All contactor failures are
considered dangerous.)
•
Internal failures of safety relays and the emergency stop button. These failures are
included in the PFH value of the function.

Fault exclusions


Fault exclusions (not considered in the calculations):
•
any short and open circuits in the cables of the safety circuit
•
any short and open circuits in the cabinet terminal blocks of the safety circuits.

Operation delays


Emergency stop total delay: less than 250 ms
Auxiliary
E-stop
safety
safety
relay
relay
Main
contactor
or
circuit
breaker
Charging
contactor