Siemens Simatic S7-300, Hardware And Installation Manual, Page: 40 / 242

Configuring
S7-300 Programmable Controller Hardware and Installation
4-12
A5E00105492-01
Open cabinets Closed cabinets
Mainly inherent
heat dissipation,
with a small portion
across the cabinet
wall. Higher heat
dissipation with
increased air
movement. Heat dissipation
only across the
cabinet wall; only
low power losses
permitted. In most
cases heat
concentration
develops at the top
of the cabinet
interior. Heat dissipation
only across the
cabinet wall.
Forced convection
of the interior air
improves heat
dissipation and
prevention of heat
concentration. Heat dissipation by
heat exchange
between heated
internal air and
cool external air.
The increased
surface of the
pleated profile of
the heat exchanger
wall and forced
convection of
internal and
external air provide
good heat
dissipation.
Degree of
protection IP 20 Degree of
protection IP 20 Degree of
protection IP 54 Degree of
protection IP 54 Degree of
protection IP 54
Typical power dissipation under following marginal conditions:
•
Cabinet size: 600 mm x 600 mm x 2,200 mm
•
Difference between the outer and inner temperature of the cabinet is 20 °C (for other temperature
differences refer to the temperature charts of the cabinet manufacturer)
up to 700 W up to 2,700 W (with
fine filter up to
1,400 W) up to 260 W up to 360 W up to 1,700 W
The cabinet's power dissipation
The power dissipation capability of a cabinet depends on its type, ambient
temperature and on the internal arrangement of devices.
Details on power dissipation ...
is found in the Siemens catalogs NV21 and ET1.
Cabinet dimensions
Note the following specifications when you determine the dimensions of a cabinet
suitable for an S7-300 installation:
•
Space required for module racks (profile rails)
•
Minimum clearance between the module racks and cabinet walls
•
Minimum clearance between the module racks
•
Space required for cable ducts or fans
•
Position of the stays
Warning
Modules are liable to get damaged if exposed to inadmissible ambient
temperatures.