Heat Measurement in Telecommunications Equipment Racks

Medium and large local digital telephone exchanges have a typical power density of 230 W/sqm of gross floor area rising to 400 W/sqm in some areas of the exchange. Individual racks within an exchange may have heat dissipations equivalent to 1 or 2 kW or more. As future exchanges become physically smaller, rack consumption and power densities will increase. A number of thermal management options are available to the telecommunications equipment practice designer. In the U.K., current practice is to use natural convection, serial air flow rack designs but the use of paral1el air f1ow has significant advantages. In recent years, British Telecom and its major U.K. suppliers have conducted practical research into the thermal performance of equipment racks and have collaborated in the development of a new, parallel air flow rack practice. This paper reviews this work and illustrates how it has led to the production of thermal guidelines for rack designers and equipment planners.