Siemens SIMATIC S5-100U, System Manual

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S5-100U Installation Guidelines
3.3.2 Electrical Configuration with External I/Os
Figures 3-18, 3-19, and 3-20 display different configuration possibilities. Pay attention to the
following points when you design your configuration. The numbers appearing in parentheses in the
following points refer to the numbers in Figures 3-18 to 3-20.
• You must have a main switch (1) in accordance with VDE 0100 for your S5-100U, the sensors,
and the actuators.
• You do not need an additional fuse (2) to connect your S5-100U and the load circuit to power if
your radial lines are a maximum of 3 meters (9.84 feet) long and are inherently earth-fault proof
and short-circuit proof.
• You need a load power supply (3) for 24 V DC load circuits.
- You need a back-up capacitor (rating: 200
µ F per 1 A of load current) if you have non-
stabilized load power supplies.
• If you have AC load circuits, galvanic isolation via a transformer (4) is recommended.
• You should ground the load circuit at one end. Provide a removable connection (5) to the
ground conductor on the load power supply (terminal M) or on the isolating transformer.
- You must provide earth-fault monitoring for any non-grounded load circuits.
• You must separately fuse (6 and 7) the load voltage for sensor circuits and for actuator circuits.
• You must connect the standard mounting rail of the S5-100U to the ground conductor through a
capacitor (8, to suppress high-frequency noise) for a non-grounded configuration.
• You must have a low-resistance connection between the standard mounting rail and the
cabinet’s chassis ground (10) for a grounded configuration.
• You need a power fuse (9) to protect against a short-circuit occurring in the power supply.
EWA 4NEB 812 6120-02b
3-21