In the design of lines and equipment considering the minimum level of insulation required, it is necessary to define surge voltage in terms of its peak value and return to lower values in terms of time or duration. Although the peak voltage may be considerably higher than normal voltage, the stress in the insulation may exist for only a very short period of time.
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Whenever a over voltage surge appears in the system, it is discharged through surge protecting devices before the equipments of the system gets damaged. Hence, the insulation of such equipment must be designed to withstand a certain minimum voltage before the over voltage surge gets discharged through surge protecting protection devices. Hence, operating voltage level of surge protecting devices must be lower than the said minimum voltage withstanding level of the equipment. This minimum voltage rating is defined as BIL or basic insulation level of electrical equipment.
Basic Insulation Level (BIL)
Insulation levels recommended for a number of voltage classes. As the operating voltages become higher, the effect ofa surge voltage becomes less; hence, the ratio of the BIL to the voltage class decreases as the latter increases.
Rated current values according to IEC 62271-1 (High-voltage switchgear and controlgear – Part 1: Common specifications)
Webcast presentation on Feb. 23, 2016 by Sherry Rollins, senior offer management specialist, Schneider Electric, Nashville, Tenn.; with James Stacy, director of medium voltage, offer strategy, U.S. Energy Business, Schneider Electric participating in the Question and Answer session. Courtesy: CFE Media
In addition, all required arc tests were completed at 28 kA at 15.6 kV successfully. The ABB VM1 breaker was extensively tested to ANSI-IEEE standards. The VM1 breaker is a magnetically actuated, vacuum circuit breaker proven to be very reliable across the globe in many applications.
Based on the response to recent seminars, the topic of medium voltage equipment and installations is one of high interest. This article will provide a brief history of the evolution, as seen by the author, of the industry and give a high-level overview of a few key areas from the product standpoint and terminology.
MV-GEAR-X Medium voltage switchgear
Following the successful type testing at KEMA’s facility in the Netherlands, NOJA Power are pleased to unveil their new 38kV Automatic Circuit Recloser system rated to 16kA fault break with a 1000 ampere one hour overload time. With these type test certificates awarded to NOJA Power, the new OSM38-16 recloser gains access to even more applications within the modern distribution utility network.
BUS DUCT & CABLE BUS DUCTS
Epoxy material is strong and requires little maintenance. As a dry type transformer, there are no hazardous liquids or materials to pose a safety risk. Since they do not contain hazardous materials, Epoxycast transformers do not require transformer vaults that limit placement options and significantly add to the cost of liquid transformers.