Table 4-5 Cabinet Types - Siemens Simatic S7-300 CPU 31xC Series Installation And Operating Instructions Manual

Overview of typical cabinet types
The table below gives you an overview of commonly used cabinet types. It shows you the
applied principle of heat dissipation, the calculated maximum power loss and the degree of
protection.
Table 4-5 Cabinet types
Open cabinets
Enclosed ventilation by
means of natural
convection
Mainly inherent heat
dissipation, with a
small portion across
the cabinet wall.
Degree of protection
IP 20
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
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
Increased enclosed
ventilation
Higher heat dissipation
with increased air
movement.
Degree of protection
IP 20
up to 2,700 W (with
fine filter up to
1,400 W)
Closed cabinets
Natural convection
Heat dissipation only
across the cabinet
wall; only low power
losses permitted. In
most cases, the heat
accumulates at the top
of the cabinet interior.
Degree of protection
IP 54
up to 260 W up to 360 W
4.7 Selection and installation of cabinets
Forced convection with
rack fan, improvement
of natural convection
Heat dissipation only
across the cabinet
wall. Forced
convection of the
interior air improves
heat dissipation and
prevents heat
accumulation.
Degree of protection
IP 54
Configuring
Forced convection with
heat exchanger,
internal and external
auxiliary ventilation
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 54
up to 1,700 W
4-13