Sls Reaction When Modulation Is Lost During Deceleration Ramp, With Ramp Monitoring - ABB ACS880-07 User Manual

1. The user or a PLC activates the SLS request of the FSO module, that is, switches the
digital inputs of the FSO module from 1 to 0.
2. (From (2) to (3)) After the safety function response time (A), the drive starts to ramp
down the motor speed. The ramp is defined and monitored using the SAR1 parameters
of the FSO module (see SAR1 parameters 200.112 -SARx.22 and SARx.02). The FSO
module monitors the actual deceleration rate of the motor against the ramp monitoring
settings. The FSO module starts SLS monitoring and energizes the digital output that
indicates the SLS status when the motor speed is in the middle of the SLS1 trip limit
and the SLS1 limit.
(2b) If the motor speed does not follow the ramp monitoring limits, the FSO module
activates the STO function. The motor coasts to a stop.
Note: In the +Q978 option, the SBC function is used to control the main
contactor/breaker. If you have this option in the drive, the main contactor/breaker is
opened if a ramp monitoring limit is reached.
Note: In this case, the FSO activates the SLS indication when the motor speed goes
below the SLS1 limit positive (B).
3. The actual motor speed reaches the SLS1 limit positive.
(From (3) to (4)) The drive limits the motor speed reference so that the motor speed
stays below the SLS1 limit positive. The FSO module monitors the actual motor speed.
If the motor speed still goes above the SLS1 trip limit positive (C), the FSO module
activates the SSE function (see section SLS with speed below the monitored speed).
(3b) The motor speed goes below the zero speed limit (D). If the motor speed did not
follow the ramp at 2b, the STO acknowledgement becomes allowed now. The user must
reset the drive if the STO indication parameter (FSOGEN.62 or 31.22) has been set so
that a fault is generated. See chapter General parameters.
4. The user or a PLC removes the SLS request of the FSO module, that is, switches the
digital inputs of the module from 0 to 1. The FSO module acknowledges the SLS function
automatically. This is set to be automatic by an FSO parameter (SLSx.02), and no
external acknowledgement input is in use. The FSO module stops SLS monitoring and
de-energizes the digital output that indicates the SLS status. The drive returns to normal
operation and starts to follow its ordinary speed reference. The drive accelerates the
motor to the desired speed along its acceleration ramp (drive parameter).
5. Normal operation

SLS reaction when modulation is lost during deceleration ramp, with ramp monitoring

The following functionality is relevant only with speed estimate feedback for functional safety
purposes.
If SLS function is activated when motor speed is above the SLS trip limit, FSO will force the
drive to decelerate to SLS limit. If the drive stops modulating during this deceleration ramp,
user can select the reaction of the SLS function (parameter SLSx.05) from the following:
• Modoff delay time
• Monitoring active
• Monitoring active and modoff delay time
• Monitoring and modoff delay time disabled.
Following examples explain the FSO behavior with each of the selections when speed
estimate feedback is used for functional safety purposes. These features are used with
SLS1...SLS4 functions and the variable SLS function. Note that these features are also
Option description 21