Elec­tri­cal light­ing sys­tems, their in­stal­la­tion and main­te­nance

Panay News - - REGION - By Reny F. Gaje, Teacher III, Este­fa­nia Mon­temayor Na­tional High School, Du­marao, Capiz

ELEC­TRI­CAL light­ing sys­tems form part of the Elec­tri­cal and In­stal­la­tion Main­te­nance ( EIM) les­son in high school. Con­sid­er­ing the type and quan­tity of loads placed into most fa­cil­i­ties, one fact be­comes clear: The light­ing sys­tem is one of the most per­va­sive of the elec­tri­cal loads.

Light­ing can cre­ate l ocal­ized elec­tri­cal field prob­lems and af­fect sus­cep­ti­ble elec­tronic equip­ment. In this ar­ti­cle, some of the is­sues as­so­ci­ated with elec­tri­cal noise (both con­ducted and ra­di­ated) that light­ing sys­tems can gen­er­ate is dis­cussed.

Do you know what the typ­i­cal light­ing sce­nar­ios are? Field in­stal­la­tion guides for com­puter sys­tems fre­quently con­tain warn­ings that ad­vise users to avoid pow­er­ing flu­o­res­cent light­ing sys­tems from the same panel boards that sup­ply power to com­puter sys­tems.

In large fa­cil­i­ties, it’s un­usual to find light­ing sys­tems pow­ered from the same elec­tri­cal panel that serves com­puter equip­ment, since light­ing sys­tems are of­ten pow­ered from 480/277V, three­p­hase, four- wire sys­tems. How­ever,

you can’t say the same for small of­fice en­vi­ron­ments in which 208/ 120V, three- phase, four- wire is the sole power source con­fig­u­ra­tion. Even if the 480/277V and 208/120V sys­tems are sep­a­rate, in­stal­la­tion prob­lems may en­able cou­pling be­tween the power sys­tems. This holds true with tele­vi­sion re­ceivers (i.e., ABS-CBN TV Plus box), aux­il­iary equip­ment, VCR, and home theater that are af­fected, or will cease to func­tion at some point due to light­ing sys­tem or merely with the pres­ence of quite a high-pow­ered/ volt­age flu­o­res­cent lamp.

There i s also the con­ducted in­ter­fer­ence light­ing sys­tem. While en­ergy usage is cer­tainly im­por­tant from a cost per­spec­tive, the power sig­na­ture of light­ing sys­tems is equally im­por­tant, but from an elec­tro­mag­netic com­pat­i­bil­ity stand­point. Older flu­o­res­cent light­ing sys­tems used fer­rores­o­nant bal­lasts, which were not ex­tremely ef­fi­cient. Also, the power fac­tor of their cur­rent draw was of­ten quite low.

And there is also the so- called ra­di­ated in­ter­fer­ence. Whereas the old fer­rores­o­nant bal­last re­lied on a sat­u­rat­ing trans­former for reg­u­la­tion of lamp cur­rent and volt­age, to­day’s mod­ern elec­tronic bal­last rec­ti­fies the ap­plied AC volt­age and then sup­plies the lamp with high-fre­quency volt­age from pulse-width mod­u­la­tion (PWM) in­vert­ers.

As a re­sult, a high- fre­quency elec­tri­cal field, which matches the ap­plied volt­age f rom the PWM in­vert­ers, de­vel­ops at the flu­o­res­cent

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