Safe Stopping Functions; Introduction To The Safe Stopping Functions - Danfoss Vacon OPTEA Operating Manual

VACON® NXP Advanced Safety Options
Operating Guide
The acceleration ramps are valid only for the SSR function. The acceleration ramps are defined in the same way as deceleration
ramps. A nominal speed value (shared with the deceleration ramp) and two time values that represent the maximum and minimum
time that the ramping is permitted to take. The actual monitored ramps are calculated when ramp monitoring starts.
(SSR_Min_Limit rpm − Speed rpm ) × Ramp_Acc_Time_Min s
SSR_Acc_max s =
(SSR_Min_Limit rpm − Speed rpm ) × (Ramp_Acc_Time_Min s − SSR_td1 s
SSR_Acc_min s =
where Speed is the speed at the time of the calculation. SSR_Acc_Max and SSR_Acc_Min are the time from ramp start (A and B)
where speed should be at the monitored minimum limit speed (C and D). Rampx_speed is the nominal speed for the ramp set. At
any given point during the ramp monitoring the actual value of monitoring is calculated from the slope connecting the respective
points.
Rampx Speed
SSR Max Limit
SSR Min Limit
Speed
Illustration 27: Acceleration Ramps, the SSR Function as an Example
A Start of the minimum acceleration ramp
B Start of the maximum acceleration ramp
The response to a ramp violation is the STO(+SBC) function for safe stopping functions, and the SQS function for safe monitoring
functions.

6.2 Safe Stopping Functions

6.2.1 Introduction to the Safe Stopping Functions

The safe stopping functions are used to start and monitor the stopping of the motor. The safe stopping functions do not take into
account the rotation direction of the motor when they are in the optional zero speed or the ramp monitoring mode. The SOS func-
tion is an exception, it takes into account the rotation direction of the motor.
The priority of the safe stopping functions from the highest to the lowest:
1. The STO function
2. The SQS function
66 | Danfoss A/S © 2021.06
Rampx_speed rpm
Rampx_speed rpm
Speed
Rampx Acc Time Min
A
SSR td1
SSR Acc Min
N O T I C E
Rampx Acc Time Max
C
D
B
SSR Acc Max
Nominal Acceleration Ramp
Scaled Acceleration Ramp
C End of the minimum deceleration ramp
D End of the maximum deceleration ramp
Safety Functions
t
AQ319736045637en-000101 / DPD01798