Danfoss VLT FC 280 Operating Manual page 64

Operating Guide | VLT® Midi Drive FC 280
f
A
1
3
Figure 32: Safe Stop 1 Time Controlled
1 Activation of SS1-t
3
Parameter 42-42 Delay Time
A Actual frequency
SS1-t function activates a braking ramp defined from a selected time delay in parameter 42-42 Delay Time, which means the braking
ramp is linear. Select the value of parameter 42-43 Delta T (the percentage of delay time), which is a reasonable tolerance before the SS1-
t time expires.
Using SS1-t may result in the motor still spinning when the Safe Torque Off is activated. The risk analysis for the machine must
indicate that this behavior can be tolerated. An interlock may be required.
For SS1-t, ramping down the motor is performed by non-safety components, so it may fail undetected. Therefore, SS1-t cannot be
applied if this failure can cause a dangerous situation in the final application.
The SS1-t function does not monitor the reality of the motor's stopping. If any drive's fault occurs before SS1-t time expired, the
drive coasts immediately regardless of the motor speed.
Assess the suitability of SS1-t for end application.
l
Parameter 42-43 Delta T provides a time margin, the drive should have stopped before entering the time margin. Too much of
Delta T can bring a steep ramp down curves, which may cause overcurrent and coast the motor.
64 | Danfoss A/S © 2024.10
t
4
2
2 Activation of Safe Torque Off
4
Parameter 42-43 Delta T
WARNING
NOTICE
NOTICE
NOTICE
Safety Functions
AQ381425076031en-000201 / 130R1223