Investigating University Personnel Computers (PC) Produced Harmonics Effect on line Currents

Abstract

Nonlinear loads connected to a sinusoidal source inject  harmonic  currents  into  the  source.  Nonlinear  load  is  a load  that  draws  none  sinusoidal  current  wave  when  supplied by  a  sinusoidal  voltage  source.  Much  attention  has  been focused on large power converters as sources of harmonics due to  the  high  magnitude  of  the  currents  evolved.    Nevertheless, harmonics   generated   by   low   power   converters   become significant   when   large   numbers   of   converters   are   used simultaneously.  In  this  paper  the  influence  of  the  personal computers  in  the  line  current  harmonics  in  some  buildings  at King  Fahd  University  of  Petroleum  and  Minerals  (KFUPM) have  been  investigated.  The  harmonics  were  monitored  from the main switched boards of each building that has the highest number of PC’s and from the switch boards  of each computer labs  in  these  buildings.  This  investigation  may  help  in  pin-pointing the  harmonic  generating  sources,  effects,  and how to mitigate,   also   to   obtain   the   actual   PC   operation   of   the university   and   its   harmonic   contribution.   Measurements indicate  that  two  buildings  of  the  highest  PC's  numbers  do have harmonics but one building harmonics is higher than that allowed  by  IEEE-519  standards  [1]  limits  and  the  other  does not influence phase current and it is within allowable limits.