05-03-2010 05:25 AM
First of all George, if you are working in Riyadh, then this problem was actually created by your own team. As i visited the site & on the very first visit i found droop CTs were fixed on phase V rather phase U and this information was passed by your own technicians from Jeddah. These are the wordings which your technicians have informed me. Originally the case was that AVRs were burning due to unknown reason, as Droop CT rating wasn't clear among the specsheets of R448. Later i explored the R448 catalogue & found out the rating was 1A on secondary end. The wrong information was spread among your collegues that shifting all CTs on phase V of 1600:5A will solve their problem which actually wasn't the case. This is my personal experience which i have solved & send notification to your Co. aswell.
1) Droop CT shall be of 1600:1 or 2000:1 not 1600:5 or 2000:5 (bigger CT of 5Acan be used if the secondary end has less amperage)
2) NO STEP SHOULD BE TAKEN IF YOU ARE NOT SURE WHAT WILL BE THE OUTCOME OF IT.