Pilz PSS 3075-3 Series, Руководство пользователя

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Wiring the Inputs and Outputs
7-2 Operating Manual: PSS 3075-3 Series
Notes on wiring
Where safety-related applications are concerned, it is essential that short
circuits and open circuits are unable to cause a hazardous condition within
a plant.
The way in which this is done will depend on the degree of hazard within
the plant itself, the switching frequency of the input devices and the level of
safety of the input devices and actuators. You should assess these points
in conjunction with the relevant standards or approvals body (e.g. BG or
TÜV).
Please observe the following when wiring:
• Earthing:
- Connect the housing to the central earth bar.
- A cable cross section of at least 2.5 mm
2
should be used.
- Connections should be kept as short as possible.
• Open circuits, short circuits and earth faults:
- In principle it is possible to eliminate short circuits between signals
within electrically-enclosed areas and also outside electrically-enclosed
areas when the signals are conducted in different multicore cables.
However, all components must meet the relevant regulations in
accordance with EN, DIN and VDE.
- Open circuits and earth faults cannot be eliminated.
- With multi-channel input devices with frequent operation, short circuits
and open circuits can be detected via feasibility checks in the control
program.
- The input test on the programmable safety system uses test pulses to
enable the system’s operating program to carry out a test to detect
open circuits and short circuits.
• If a dual-pole output on the programmable safety system is used to drive
the actuators, a test for short circuits and open circuits will automatically
be carried out during each cycle. For this purpose the actuator will be
switched off for approx. 100 µs.
• Where single-pole outputs or test pulse outputs are being used, a switch-
off test will not be carried out in each cycle. The time for the test will
depend on the test slices in the configurable self-check.
• Connecting and laying the cables
- Screened cables are not required for digital I/Os. However, if the
connection cables have screening, it should be connected at one end.