Milli-Triarc spark gaps are designed for electrical transient protection of balanced pair communications lines. Their three-electrode design provides a discharge path from each line to ground in addition to a line-to-line path for metallic surges. They may also be used for triggered applications where an adequate trigger pulse is available.

When installed on balanced pair lines, where symmetrical surge voltages are anticipated on each line pair, this three electrode series provides for a rapid sympathetic breakdown of the opposite line electrode to ground following the initial line to ground breakdown. The delay, t2-tl shown in the diagram below, is considerably shorter with this series of spark gaps than that found where two separate two electrode spark gaps are used. The milli-triarc type tube also provides line-to-line surge protection. These tubes are capable of a 10,000 ampere (8 x 20 usec waveshape) surge. Insulation resistance is greater than 1 x 10E9 ohms. Capacitance is less than 2 pF.

Normally, stocked units are as follows. Other breakdown voltages to 2000 volts are available on request.