Siemens SIMATIC S7 Functional Safety Manual page 81

If you locate the PLC in an area where conductive contamination may be present, the PLC
must be protected by an enclosure with appropriate protection rating. IP54 is one rating that
is generally used for electronic equipment enclosures in dirty environments and may be
appropriate for your application.
Improper installation of the S7-1200 can result in electrical faults or unexpected operation
of machinery.
Electrical faults or unexpected machine operation can result in death, severe personal
injury, and/or property damage.
All instructions for installation and maintenance of a proper operating environment must be
followed to ensure the equipment operates safely.
Separate the S7-1200 devices from heat, high voltage, and electrical noise
As a general rule for laying out the devices of your system, always separate the devices that
generate high voltage and high electrical noise from the low voltage, logic devices such as
the S7-1200.
When designing the layout of an S7-1200 inside your panel, consider the heat generating
devices and locate electronic devices in the cooler areas of your cabinet. Reducing the
exposure to a high temperature environment extends the operating life of any electronic
device.
Consider also the routing of the wiring for the devices in the panel. Avoid placing low voltage
signal wires and communications cables in the same tray with AC power wiring and high
energy, rapidly switched DC wiring.
Provide adequate space for cooling and wiring
S7-1200 devices are designed for natural convection cooling. For proper cooling, you must
provide a clearance of at least 25 mm above and below the devices. Also, allow at least
25 mm of space between the front of the modules and the inside of the enclosure.
For vertical mounting, the maximum allowable ambient temperature is reduced by 10
degrees C.
Orient a vertically mounted S7-1200 system as shown in the following figure.
Ensure that the S7-1200 system is mounted correctly.
S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA
WARNING
CAUTION
Fail-Safe CPU and signal module (SM) installation
4.1 S7-1200 Fail-Safe modules installation and removal
81