ABB FSO-21, User Manual

Page: 165 / 540

Safety functions 165
Note: With time-monitored SLS: If modulation is lost during deceleration ramp but it
returns after SLSx.04 delay time has elapsed, with motor speed higher than SLS trip
limit, then SLS limit hit is generated.
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.
SLS delay time monitoring is switched off (parameter
SLSx.04 ) as Monitoring and
modoff delay time are disabled.
FSO starts to wait until the
STO.14 delay has run out or modulation returns.
3 The drive modulation returns.
Deceleration continues toward SLS limit speed.
4 FSO starts the SLS monitoring when the motor speed is in the middle of the SLS limit
and the SLS trip limit (see also section
How to configure mute time for monitoring start
on page 399 ).
The SLS indication goes on.
5 FSO starts the SLS monitoring at the latest here, that is, after the SLS time delay has
elapsed.