Safety Integrated - Industry - Siemens

Single and Group Shutdown of Actuators in Safety Category 4
acc. to EN 954-1
Automation Function
Description of the functionality
Single and group shutdown
When using several actuators within a system, the following
behavior is often required: It is to be possible to safely power
an individual actuator down (independent of the other actuators).
Additionally it should be possible to safely switch off all
actuators together.
Functional example
This example shows single and group shutdown of actuators.
Two three-phase asynchronous motors which can be started
independently of one another are used. An emergency stop
button is assigned to each motor for safe stopping (single
shutdown). Furthermore, there is an emergency stop button
which safely stops all motors (group shutdown).
Operational stopping of motors has not been included in this
example.
Allocation contactors - motors
Group 1 consists of the motor M1 which is switched via the
contactors K1 and K2.
Group 2 consists of the motor M2 which is switched via the
contactors K3 and K4.
If a readback error is detected in a group, this group is
stopped. Safe operational start and stop of the other group is
still possible.
Safety Category
The actuator shutdown via failsafe outputs of the ET 200S
shown here complies with Safety Category 4 according to
EN 954-1: 1996.
Reaction times
For calculating the max. reaction time of your F-system please
use the Excel file (Cotia table), which is available for S7 Distributed
Safety V 5.3. This file is available on the internet:
http://support.automation.siemens.com/WW/view/en/
19138505
Failsafe input and output modules
One failsafe input and output module of the ET 200S switching
the following variables is used in each case:
Failsafe… Signals
Input module (F-DI) Emergency stop button for group 1
Emergency stop button for group 2
Emergency stop button for both groups
Output module (F-DO) Switches all contactors (K1, K2, K3, K4).
Standard input modules
The standard input modules read the signals listed below for
each group:
■ Start request
■ Acknowledgement
■ Readback signals of the contactors
In addition, an acknowledgement signal exists with which an
acknowledgement can be transmitted for all groups.
Acknowledgement
An acknowledgement is required
■ prior to the first start
■ after a readback error (acknowledgement with the
acknowledgement push button assigned to the group or
the acknowledgement push button applying to all groups)
■ after activating an emergency stop push button after this
push button was unlocked manually (acknowledgement
either individually for each group with the assigned
acknowledgement push button or with the acknowledgement
push button applying to all groups)
■ after the reintegration of the passivated F-DI
Recognizing a welding
A readback error occurs, for example, when a contacts welds.
This error is revealed in the program code by the use of a certified
block from the Distributed Safety block library. Starting
the application is only possible if the error was corrected and
if an acknowledgement was transmitted.
Functional Example No. AS-FE-I-009-V10-EN 277
Ex. No.
9