Siemens Simovert Masterdrives Compendium page 75

12.2010
Subsystem
EVALUATE
Parameter
Safety switching devices 3TK2842 -A2 and –A3
PFH
d
Service life
Performance Level
Result
PFH
d
Performance Level
Subsystem REACT
Siemens AG 6SE7087-6QX70 (Version AM)
SIMOVERT MASTERDRIVES
In this example, the subsystem EVALUATE is provided by two SIRIUS
3TK2842 safety switching devices. The safety switching devices feature
instantaneous and time-delayed electronic enabling circuits.
The device –A3 provides a safe time delay for switch-off and is
energized via the cascading input terminal 1. Both devices –A2 and
–A3 are used to evaluate the door switches and checkback signals
from the contactor relays.
Value
-11
5.4 x 10 / h
T1 = 20 years
PLe
-10
1.08 x 10 / h
PLe
The subsystem REACT is formed by two channels. The first channel
consists of the safety relay –K1. The second channel consists of the
line contactor –K2 and the contactor relays –K3 and –K4.
In this example, the subsystem REACT is formed by two channels with
different request rates for each channel. A dangerous fault in channel 1
causes an instantaneous request from channel 2.
The components –K1, –K3 and –K4 are tested every time –A2 or –A3
starts.
The contactor –K2 is tested every time –A1 starts.
Accumulation of faults in channel 2 between two consecutive actuations
of the Emergency Stop button is not detected.
♦ The structure conforms to fundamental and proven safety principles
and the requirements of Category B. Protective circuits are
provided.
♦ The safety function always remains operative when a component
fails. Component failure is detected.
This structure corresponds to Category 3 in accordance with EN ISO
13849-1:2008 /R3/.
Compendium Motion Control
Configuration and Connection Examples
Comment
Specified by manufacturer
Specified by manufacturer
with Category 4
PFHd = PFHd ( − A ) 2 + PFHd
with Category 4
( − A ) 3
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