3
Safety concept
Drive safety functions
Manual – MOVISAFE
®
CS..A Safety Card
22
3.7.5
SS2(c) – Safe Stop 2
When the SS2(c) function is active, the drive inverter brings the motor to a standstill
electrically. At standstill, the drive inverter delivers the power to keep the motor in pos-
ition. The position must be safely monitored after a specified, safety-relevant time has
elapsed (SOS function according to EN 61800-5-2). Any movement at standstill trig-
gers the STO drive safety function. STO means that standstill has to be ensured by a
mechanical brake.
This drive safety function corresponds to a controlled stop of the drive according to
EN 60204-1, stop category 2.
t
1
t
2
t
∆
t
V
9007201429937291
= Drive safety function monitored
= Drive safety function trips
v
= Speed
t
= Time
t
1
= Point of time when SS2(c) is activated and motor deceleration is triggered.
t
2
= Point in time when SOS is triggered.
Δt
= Safety-relevant period of time
INFORMATION
•
The SS2(c) function does not monitor the stopping of the drive.
•
The safety-relevant period of time Δt allows the drive to come to a stop. In the
event of a fault, the drive does not come to a stop. It will not be de-energized until
the time t
2
(STO).
24842532/EN – 04/2018
