Measurement and analysis on electromagnetic shielding effectiveness of a 500kV UPFC valve hall

The 500 kV Unified power flow controller (UPFC) valve hall is a large size shielding enclosure with dimensions up to 135.9m𢈗30m𢈗14m. Its shielding measures is based on lots of steel sheet with a thickness of 1 mm covered on the surface of the building. In this paper, the electromagnetic shielding effectiveness of the 500 kV UPFC valve hall was measured for three frequencies between 14kHz-15MHz using loop antenna and another three frequencies between 100MHz to 950 MHz using halfwave dipole antenna. The Test results show that the electromagnetic shielding effectiveness of the valve wall are above 40dB, which satisfies the corresponding standard requirement in China. In addition, the effect of the door status(opening/closing), the alignment of the emitting antenna and receiving antenna, the emitting antenna to wall distance are discussed.