Leadership

Three-Electrode Unit Called Better Lightning Arrester

Issue 5 and Volume 130.

Three-Electrode Unit Called Better Lightning Arrester Traditionally, two-electrode lightning arresters have been used to protect each pair of fire communications lines. Since surges are always out of phase, one two-electrode unit will ground the line carrying the first power surge. However, there are two lines to the equipment and grounding one leaves the second line at a high potential. For the late surge on this second line to reach ground, it takes the only path open to it, which goes right through the equipment. The telephone industry has found a solution to this problem which is relevant to fire communication. It is replacing two-electrode units with threeelectrode gas tube arresters. The three-electrode gas tube has one electrode for each of the wires in a line pair, plus one electrode for ground. The three-electrode gas tubes operate by grounding both lines instantly if either one is surged. This prevents differential voltage…

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