User's Manual

Navini Networks, Inc. Ripwave Base Station I&C Guide
Part #40-00047-00 Rev D v1.0 205
February 28, 2003
Thermal Management
General
Outdoor cabinets utilize various methods to maintain a cabinet’s internal temperature with
acceptable operating ranges of equipment installed within the cabinet. Thermal management
includes management of heat gain from internal and external sources, as well as heat loss, to a
lesser extent, due to low winter air and ground temperatures. A BTS installed in an outdoor
cabinet will likely be impacted to a greater extent by environmental conditions during summer
months, due to a combination of radiant solar heat gain and outside air/ground temperatures,
which limit the cabinet’s ability to dissipate internally generated heat out of the cabinet. During
winter conditions, except in extreme conditions, thermal dissipation by electric and electronic
equipment and components inside the cabinet are generally sufficient to maintain the interior
temperature of the cabinet at a level within the operational range of all installed equipment.
Heat Transfer
Heat may enter (or exit) an outdoor cabinet in one of three transfer modes: conduction,
convection, and radiation (radiant heat). Heat gain and loss from conduction is a result of direct
contact between the cabinet and the foundation or other structure with which the cabinet is in
contact. Convection heat gain and loss results from the transfer of heat between the cabinet and
the outside air in contact with the cabinet. Radiant heat gain and loss results from absorption of
radiant energy from a warmer source by a cooler source. Radiant energy is transferred through
air without heating the air. Every material or object with a temperature above absolute zero emits
radiant energy in all directions until it is deflected or absorbed.
For an outdoor cabinet, the primary method of heat gain into the interior of the cabinet is usually
from radiant heat from the sun, although convection and conduction will play varying but usually
lesser roles. Control of each type of heat gain or loss usually requires different techniques by
cabinet manufacturers. The selection of one or more methods used to control heat gain or loss is
dependent upon the customer’s specific equipment requirements.
External Heat Sources
External cabinet heat sources primarily consist of the following:
• Radiant - sun, rooftops, nearby structures.
• Convection - structures or material in direct contact with the cabinet.
• Convection - air surrounding the cabinet.