Seismic Analysis of Telecom Battery Racks

Abstract

Earthquakes have a potential to cause serious damages to telecom system and jeopardise its continuos communication service availability. The battery is a vital part of uninterruptible power supply system for telecom equipment. Its function is to provide dc. energy without interruption at mains failure or until a standby diesel generator is started up. The learning and challenges of earthquakes have been presented in many papers. According to the study of the earthquake made by author in paper [1] during the commercial outage after the earthquakes some standby diesel generators failed to start. If this occurs the battery as a standby unit for mains or diesel generator failures takes over the feeding of telecom equipment. The traditional power system for telecom plant, composed of thyristor controlled rectifiers and conventional battery has been installed separately from telecom equipment. Generally, large conventional batteries are located on basement or the first floor in the telecom building. In many countries the conventional vented lead acid battery is replaced by valve regulated lead acid (VRLA) battery that can be put in the room of telecom equipment. Telecom system with incorporated VRLA cells of battery can be found on different floors of a telecom building. Depending on location of VRLA batteries in telecom building and seismic zones some telecom organizations require analysis of battery racks resistant to earthquakes. This paper deals with two different techniques in analysis of telecom battery racks resistant to earthquakes. classified with the aid of various scales. Since 1964. empirical MMS scales have been used in civil engineering in Europe. Earthquakes in MMS scales are classified in degrees of intensity according to their effects at human senses and building damages. In most countries magnitude scales are used (i.e. Richter). Magnitude scales are based on the recorded values of seismic energy released at an earthquake. Table 1. show the relationship between MMS and Richter scales and ground acceleration levels during earthquakes in various seismic zones.