Abstract: The apparatus which predicts the onset of thunderstorm and the occurrence of close thunderbolts, includes a composite sensor with several metal pipes radially installed with equal separation on a hemispherical electrode. A plurality of corona needles are provided on the insulator at the end of each metal pipes, and the needles are electrically connected together within the composite sensor. The hemispherical electrode is connected to a circuit that counts the number of electric field-changes for certain time intervals. In case the receiving frequency exceeds the pre-determined level, it issues a first alarm. The groups of corona needles are connected to the circuit that measures the corona current, and issues a second alarm, in case the current a pre-determined level. In addition, the circuit includes circuitry that picks up the large amplitude corona current changes that the polarity change and issues the thunderbolt warning.

Abstract: A low voltage arrester works as a lightning arrester with high energy tolerance. With installation of the lightning arrester on power lines, telephone lines or other signal input lines, all electric apparatus connected to the lines are effectively protected against lightning surges including high energy surges caused by close thunderbolts. The lightning arrester includes two elements connected in parallel. One is a series circuit of a zinc oxide arrester and a non-inductive resistor, and the other element is a spark gap formed of brass electrodes. All the arrester elements are installed in one refractory porcelain case. In order to install the arrester in a limited space and to insure tolerance of high energy surges, the non-inductive resistor uses bifilarly or Ayston-Perry wound Nichrome wire.