Title :
Vacuum Circuit Breaker Transients During Switching of an LMF Transformer
Author :
Shipp, David D. ; Dionise, Thomas J. ; Lorch, Visuth ; MacFarlane, William G.
Author_Institution :
Power Syst. Eng., Eaton Electr. Group, Warrendale, PA, USA
Abstract :
Switching transients associated with circuit breakers have been observed for many years. With the widespread application of vacuum breakers for transformer switching, recently, this phenomenon has been attributed to a significant number of transformer failures. Vacuum circuit breaker switching of electric arc furnace and ladle melt furnace (LMF) transformers raises concern because of their inductive currents. High-frequency transients and overvoltages result when the vacuum breaker exhibits virtual current chop and multiple re-ignitions. This paper will present a detailed case study of vacuum breaker switching of a new LMF transformer involving current chopping and restrike simulations using the electromagnetic transients program. A technique that involves a combination of surge arresters and snubbers will be applied to the LMF to show that the switching transients can be successfully mitigated. Additionally, some practical aspects of the physical design and installation of the snubber will be discussed.
Keywords :
EMTP; arresters; high-frequency transformers; power transformer protection; snubbers; switching transients; vacuum circuit breakers; LMF transformer switching transient; electric arc furnace; electromagnetic transient program; high frequency transient; inductive current; ladle melt furnace transformer failure; multiple reignition; restrike simulation; snubber; surge arrester; vacuum circuit breaker switching transient; virtual current chop; Arresters; Furnaces; Snubbers; Surges; Switches; Transient analysis; EMTP simulations; LMF transformer; RC snubbers; SF-6 breakers; surge arresters; switching transients; vacuum breakers;
Journal_Title :
Industry Applications, IEEE Transactions on
DOI :
10.1109/TIA.2011.2175430