Safe Stop 1 Time Controlled (Ss1-T) - WEG CFW900 Serie Manual De Seguridad

Once activated, the STO safety function removes the power from the frequency inverter's output
electronic circuit, causing the motor to coast to a stop - see
Motor
speed
0

1.2.2 Safe Stop 1 Time Controlled (SS1-t)

Differently from the STO safety function, which must promptly ensure that there is no torque-
generating on the motor, the SS1-t safety function will wait a predefined delay time before
performing the STO, in order to allow the frequency inverter to impose a deceleration ramp
to the motor before removing the torque-generating energy. The SS1-t is especially useful in
applications where high inertia loads need to be decelerated before torque is removed from
the motor.
Figure 1.2 on page 9 illustrates the behavior of the SS1-t safety function, where it is possible
to observe the controlled delay time between the green bars. STO90 should be configured with
a time value equal to or greater than the CFW900 capability to decelerate the load; otherwise,
the STO state may be reached before the complete stop of the load.
Motor
speed
0
NOTE!
According to IEC 61800-5-2, the execution of the deceleration ramp of the
SS1-t safety function may fail undetectably. Therefore, this function must not
be used if this failure could cause a dangerous situation in the final application.
STO
Figure 1.1: STO behavior
SS1-t
Figure 1.2: SS1-t behavior
Figure 1.1 en la página 9.
Time
STO
Time
CFW900 | 9
Safety