EFFECT OF THE MODULE FRONT DOOR CLOSING PROCEDURE OF A DIGITAL TRANSMISSION EQUIPMENT ON THE TEMPERATURE OF THE COMPONENTS

This work is part of an overall thermal analysis of a digital transmission equipment known as Pulse Code Modulation used by TELEBRAS, the Brazilian Telecommunications. The thermal power to be dissipated is limited by the components operating temperature that must be kept below certain values and therefore, the thermal control in this equipment is necessary.
The thermal analysis was focused in the study of the heat transfer by conduction and convection through the door of a module, known from previous works to be the predominant path for the heat dissipation into the environment. Presently the module front door is an easily detachable element held in place in the structure by means of hinges actuated by a spring. An alternative procedure using screws is analyzed in order to obtain a better contact pressure evenly distributed along the door frame. For each closing procedure a study is performed for the conduction heat transfer by identifying the thermal contact resistances between the door and the structure.
Tests were also carried out for the open module, with the front door removed. In this case a study is performed for the convection heat transfer by taking into account the penetration of the ambient air into the equipment.
Finally a comparison is made for the closing procedures with respect to the temperature of the components.