Electricalreads

For EHV Transformer 1. Take oil sample for BDV Testing every year. BDV should be greater than 80 kV in 2.5 mm gap. (Oil sample should be taken in Dry season. probably form Nov. to Feb.) 2. If BDV is less than 80 kV then replace the oil of diverter switch and also clean n flush the diverter switch. (without racking out from Main Tank) 3. Even if BDV is greater than 80kV replace the oil biannually invariably. Also clean n flush the diverter switch. (without racking out from Main Tank) 4. If any abnormal test results found in winding resistance test then overhauling of Diverter switch by Racking out / Dismantling /reassembling to find out the detail root cause of variation in test result. 5. While carrying out work Gear Box of Horizontal Lever to be attended for oiling greasing. 6. Check for working of heaters in OLTC control Box 7. Check for vermin proofing of OLTC control Box. 8. Check for OLTC Operation Remote/Local Electrical & mechanical. 9. Check for simultaneous operation of al...

SF6 (Sulfur Hexafluoride) is used in GIS/switchgears due to its high arc quenching  capabilities and very high die-electric strength (2.5 times of air). Purity & Dew point  of SF6 Gas are very important as an insulating media.  General guidelines are necessary to establish an acceptable range of moisture and SO2 levels in SF6 Gas. Dew point: The temperature at which the water vapor in the Gas begins to  condense. It is absolute measure of moisture content available in gas. It is  expressed in ºC/ºF, PPMv(Volume) and PPMw(mass). All three units refers to  same physical interpretation. If value in one unit available other two can be  derived using appropriate formulas. Mostly kit internally converts values to  provide values in all three units. There are certain factors that needs to be considered while taking dew point  measurements and interpretation of results. i.e. instrument used, Date/time  of measurement, pressure of the gas in ...