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.