ABB ACS880 Series Manual page 19

1. The user or a PLC de-energizes the applicable digital inputs of the FSO module. This
activates the SLS request.
2. After the safety function response time (A), the FSO module starts to monitor the motor
speed. The FSO module energizes the digital output that indicates the SLS status.
While the monitoring is active, the drive limits the motor speed so that it stays at or below
the SLS1 limit positive. The FSO module monitors the actual motor speed.
(2b) If the motor speed goes above the SLS1 trip limit positive (C), the FSO module
activates the SSE function and the motor coasts to a stop (in this case, the SSE function
has been configured as Immediate STO, see section
function (page 40)).
Note: In this case, the FSO activates the SLS indication when the motor speed goes
below the SLS1 limit positive (B).
Note: In option +Q978, the SBC function is used to control the main contactor/breaker.
If the drive has this option and a trip limit hit occurs, STO activation causes the main
contactor/breaker to open.
3. The user or a PLC energizes the applicable digital inputs of the FSO module. This
deactivates the SLS request. The FSO module acknowledges the SLS1 function
automatically. This is set by an FSO parameter (SLSx.02), and no external
acknowledgement input is used. The FSO module stops SLS monitoring and de-energizes
the SLS indication signal.
(3b) The motor speed goes below the zero speed limit (D). If the FSO module activated
the SSE function at 2b, the STO acknowledgement is now permitted. The user must
reset the drive if the STO indication parameter (FSOGEN.62 or 31.22) is set so that a
fault is generated.
Option description 19
Parameters for the SSE