Installing The Field Wiring - Siemens Simatic S7-200 System Manual

Installing an S7-200 Micro PLC
2.3

Installing the Field Wiring

Warning
!
Attempts to install or remove S7-200 modules or related equipment when they are
powered up could cause electric shock.
Failure to disable all power to the S7-200 modules and related equipment during
installation or removal procedures may result in death or serious personal injury, and/or
damage to equipment.
Always follow appropriate safety precautions and ensure that power to the S7-200
modules is disabled before installing field wiring.
General Guidelines
The following items are general guidelines for designing the installation and wiring of your
S7-200 Micro PLC:
Ensure that you follow all applicable electrical codes when wiring the S7-200 Micro PLC.
Install and operate all equipment according to all applicable national and local standards.
Contact your local authorities to determine which codes and standards apply to your
specific case.
Always use the proper wire size to carry the required current. The S7-200 modules
accept wire sizes from 1.50 mm
Ensure that you do not overtighten the connector screws. The maximum torque is
0.56 N-m (5 inches-pounds).
Always use the shortest wire possible (maximum 500 m shielded, 300 m unshielded).
Wiring should be run in pairs, with a neutral or common wire paired with a hot or
signal-carrying wire.
Separate AC wiring and high-energy, rapidly switched DC wiring from low-energy signal
wiring.
Properly identify and route the wiring to the S7-200 module, using strain relief for the
wiring as required. For more information about identifying the terminals, see the data
sheets in Appendix A.
Install appropriate surge suppression devices for any wiring that is subject to lightning
surges.
External power should not be applied to an output load in parallel with a DC output point.
This may cause reverse current through the output, unless a diode or other barrier is
provided in the installation.
Warning
!
Control devices can fail in an unsafe condition, resulting in unexpected operation of
controlled equipment.
Such unexpected action could result in death or serious personal injury, and/or equipment
damage.
Consider using an emergency stop function, electromechanical overrides, or other
redundant safeguards that are independent of the programmable controller.
2-8
2 2
to 0.50 mm (14 AWG to 22 AWG).
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02