ABB FSO-21, User Manual

Page: 112 / 540

112 Safety functions

SSE with immediate STO, SBC before STO
The operation of the SSE with immediate STO, SBC before the STO (negative SBC
delay)
is described in the time diagrams and tables below. For configuration, see
section How to configure SSE with immediate STO, SBC after or before STO on
page 353 .
The reason to use a negative SBC delay is to have the mechanical brake closed just
before the drive STO circuit is opened.
Without an encoder
A SBC delay (parameter SBC.12 ): Time from the activation of the drive STO function to the
moment when the FSO activates the SBC function (brake). In this case, the value is
negative and the FSO activates the SBC before the drive STO. If the value is zero, the
FSO activates the SBC and drive STO functions at the same time.
B SBC time to zero speed (parameter SBC.13 ): Time from the SBC activation to the
moment when the safety function is completed and the SSE completed indication
(parameter
SSE.22 ) goes on. The acknowledgment becomes allowed. You must set this
to the estimated time in which the motor brakes to a stop from the maximum speed.
C Response time (depends on system configuration, see page 532 )
Drive STO state
& indication
SSE request
Motor speed
Time
A
SSE completed
indication
1
6 5
SBC output
3
B
4
SBC.12
SBC.13
C
2
SSE state &
indication