The control gap for lightning protection

The use of air gaps between various forms of electrodes to discharge high surge voltages and thus protect expensive apparatus from damage is general, but such gaps vary in time delay and polarity characteristics and are difficult to co-ordinate with the insulation to be protected. By controlling the electrostatic field, the gap described in this paper provides a wide range of time and polarity characteristics that enables insulation co-ordination to be more readily effected.