ABB ACS880-17 - Page 24

When modulation comes backWhen modulation is lostValue of parameter SLSx.05
SLS ramp modoff reaction
Ramp monitoring (SAR1) is restarted,
Time monitoring is continued.
1)
Ramp monitoring (SAR1) is disabled,
Time monitoring is suspended.
1)
Modoff delay time
New speed taken into use.Last valid speed frozen and used.Monitoring active
New speed taken into use.Last valid speed frozen and used.Monitoring active and modoff
delay time
Ramp monitoring (SAR1) is restarted,
Time monitoring is continued.
1)
Ramp monitoring (SAR1) is disabled,
Time monitoring is suspended.
1)
Monitoring and modoff delay
time disabled
1)
Time monitoring: The time monitoring counter does not increase when the drive is not modulating. If modulation does not
return, SLS indicates safe state after coast time defined by parameter STO.14 has elapsed. If modulation returns within
the specified time:
• with the motor speed below the SLS trip limit at that time, SLS monitoring starts and the SLS output indicates a safe
state
• with the motor speed above the SLS trip limit at that time, the drive trips because of a SLS trip limit hit.
Note: When encoder feedback is used, parameters SLSx.05 and SLSx.06 have no effect.
Example 1: Modoff delay time – modulation returns before modoff delay
In this example, parameter SLSx.05 is set to Modoff delay time. The time diagram below
describes the operation of the SLS function when modulation is lost during the deceleration
ramp, and the modulation returns before the modoff delay time has run out.
Motor speed
Time
A
A
Drive modulation
SLS request
SAR1 monitoring
SLSx.06 Modoff
delay time monitoring
SLS monitoring
SLS indication
B
C
D
SAR1 ramp monitoringA
Actual motor speed (coasting after modoff)B
SLS trip limitC
SLS limitD
24 Option description