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Modicon Premium automation
platform
Use of Preventa safety modules
Presentation
(
continued)
Non-controlled safety systems
M
KM1
KM1
KM1
The control signal from the protection device (emergency stop pushbutton illustrated
to the left) acts directly on the power contactor of the machine.
In this type of scheme, the risks of simple faults are:
b
Emergency stop button being shorted.
b
KM1 contactor sticking.
When the operator presses an emergency stop button, the instruction is not
processed, and another sequence can begin following the emergency stop, despite
the presence of the fault.
In the case of failure, the safety function
(1)
is compromised.
Therefore, a reliable intermediate relay system must be used.
(1)
A safety function is a function whose non-execution or untimely execution results in the
immediate placement of the equipment into a non-hazardous position.
Safety system controlled by a Preventa safety module
KM6
M
KM5
KM6 KM5
KM5
KM6
KM6
KM5
Independent safety circuits
Redundancy
Preventa safety module
Run
Emergency
stop
KM5 and KM6 contactors
with mechnically linked contacts
Feedback loop
Preventa safety modules provide a reliable interposing relay function by
eliminating the risks of:
b
A control circuit fault (inputs).
b
A power circuit fault (outputs).
b
A fault on an internal safety module component.
The safety function remains operative whenever any one of these faults
occur.
Note: For the use of mechanically linked contacts CA2-KN22/KN31, LC1-D09/D18/D25 with
contacts which can be used in the feedback loop, please consult our Customer Care Centre.
Emergency
stop
1
2
3
4
5
6
7
8
9
10