BFY3T3 40.5kV four-position load break switch Three station/four station oil immersed load switch BFY1T3 Single-phase two-position load break switch BFY1T3 Single-phase four-position load break switch BFY3I2 12/24kV two-position load break switch BFY3I2 40.5kV two-position load break switch BFY3T3 12/24kV four-position load break switch ZGC type insulated operating rod for combined transformer Underground four station oil immersed load switch Underground two station oil immersed load switch