Lenze E94AYAE SM301 - Manual (Page 60)

Safety engineering
Safety functions
Safe stop 2
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60 EDS94AYAE EN 7.0
1.3.5 Safe stop 2
1.3.5.1 Description
Safe Stop 2 / SS2
This function corresponds to a "Stop 2" according to EN 60204.
This function serves to monitor the reaching of speed n = 0 within an adjustable stopping
time (C15305). The reached position must be kept active by the controller. The function SS2
changes to the safe operational stop (SOS) after the stopping time has expired. This
function is implemented in the SM301 up to version 1.2 as a monitoring function of a
speed band. Thus, the SOS function and accordingly the SS2 function is implemented
deviating from the EN 61800−5−2 standard which demands the monitoring of a position
windows in section 4.2.3.1. As of version 1.3, the function is implemented in compliance
with the standard, i.e. the monitoring is executed through a parameterisable position
window (C15311). Depending on the SS2 mode (C15308) the drive can also be switched
directly to the safe operational stop (SOS) after zero speed has been reached. This causes
reduced cycle times.
For speed n = 0, a tolerance window (C15310) can be parameterised. For the tolerance
window Delta p=0 (C15311), a relative position is defined by which the drive may move in
the SOS state.
From SM301 V1.3 onwards, the tolerance window for standstill detection (C15310) is used
to control the transition to the SOS state subject to the "SS2 mode" parameter (C15308).
C15308 serves to determine whether the SOS state is reached after the stopping time has
expired or after the reaching of n = 0. In the SOS state, the standstill monitoring based on
the position takes place. The respective limit value is set via the parameter "SOS: Tolerance
window (Delta p=0)" C15311.
The speed and the position are calculated from the encoder data (safe speed
measurement). Without an encoder, the function cannot be used.
If the monitored limits are exceeded, an error stop will be caused. The power supply of the
motor is immediately safely interrupted (STO). The motor cannot create a torque and thus
no dangerous movements of the drive can occur. Additional measures, e.g. mechanical
brakes are needed against movements caused by external force.
A restart is only possible after the stopping time has expired completely (up to V1.2 and
V1.3 with C15308 "SS2−mode = SOS after stopping time").
If the parameter SS2 mode = "SOS at n=0" (from V1.3), the restart can be executed after
the transition to the SOS state.
This does not apply to special operations.
From SM301 V1.3 onwards, the higher−prior stop function SS1/STO is executed when the
SS2 stop request and SS1/STO occur at the same time. After the SS1/STO request has been
cancelled and acknowledged accordingly (see restart behaviour), a direct STO transition to
the SS2/STO state can be achieved without cancelling the SS2 request. Up to SM301 V1.2,
the cancellation of all stop functions incl. SS2 before an acknowledgement was necessary
in order to reach the SOS state via an SS2 request.
From SM301 V1.4 onwards, deceleration ramp monitoring can be parameterised.
Depending on the parameterised stopping time, a monitoring ramp is calculated. (
¶ 64)