Issues of arcing on high-voltage lines and their EMC aspects for the SKA project

The Square Kilometre Array (SKA) will be the largest radio telescope in the world. Up to 3000 dishes, and more than 500,000 array elements will be linked to obtain an extreme sensitivity. The frequency band starts at 70 MHz, and goes up to 10 GHz and possibly over 25 GHz later. Arcing on high voltage lines is a potential source of interference. Gaptype sparking is known to produce large bandwidth noise, but up to now the consequences were investigated for radio and television interference, at higher levels and over a lower frequency band than SKA. A test spark gap has been constructed. High frequency current probes determined the gap current to generate arcing. Their frequency domain transfer impedance Zt has been measured, and has been used to de-convolute the measurements.