The voltage at which the initial discharge occurs with a slowly rising voltage applied across the electrodes of the tube. (The test voltage is applied at 100 volts per second or less).
The voltage at which the initial discharge occurs with a rapidly rising voltage applied across the electrodes of the tube. This breakdown voltage is a function of the rate of rise of the applied voltage and is generally stated for a particular ramp voltage.
The surge current capability of a spark gap is a function of the waveshape of the surge and of the tube design. Each spark gap design has its own inherent maximum surge current capability for a given surge waveshape. Factors such as tube and electrode size, gas fill, and gas pressure determine the tube capability.
The insulation resistance between electrodes of a spark gap is normally measured at 100 volts DC when the
|spark gap is in a non-ionized condition. As the device is used this insulation resistance decreases and normally end of life is determined when this resistance reaches a selected value.
LIGHTNING STROKE CURRENTS:
In selecting a particular spark gap for a lightning protection application, the magnitude of the stroke current must be predicted. Lightning stroke peak currents vary greatly from several hundred to several hundred thousand amperes depending on the particular stroke and whether it is induced into the equipment being protected or arrives as a direct stroke through an electrical conductor.
EMP or ELECTROMAGNETIC PULSE:
The electromagnetic radiation associated with a ther- monuclear explosion and the electrical transient coupled into circuitry due to this radiation.
The first significant current that flows following in initiation of an overvoltage condition.