ABB FSO-21 - Page 163

Safety functions 163
SLS reaction if modulation is lost with Monitoring and modoff delay time
disabled
The operation of the SLS function in case the modulation of the drive is lost during the
deceleration ramp with Monitoring and modoff delay time disabled selected
(parameter SLSx.05 is set to Monitoring and modoff delay time disabled) is described
in the time diagram and table below. For configuration, see section How to configure
SLS function behavior when drive modulation is lost on page 376.
B
Actual motor speed (coasting after modoff)
C SLS trip limit
DSLS limit
Step Description
1 The SLS request is received. The motor speed is above the SLS trip limit positive (A).
The drive starts to ramp down the motor speed.
The drive (parameter 23.13 or 23.15) defines the deceleration ramp until the speed
reaches the SLS limit.
The FSO starts the counter for the SLS time delay (C) (parameter SLSx.04)
2 The drive trips on a fault, there is a drive power loss, or user stops the drive by coast
stop. Here, STO is not activated due to loss of modulation.
STO.14 delay starts.
3 If modulation does not return, SLS indication goes on after STO.14 delay has elapsed.
SLS indication
Motor speed
Time
1 32
B
Drive modulation
SLS request
SLSx.04 time
delay monitoring
C
D
STO.14 delay