Abstract
An improved electrolysis switch has been placed in use in the Bell System for mitigation of electrolysis of cables by stray currents. It consists of three relays operating in sequence, namely control, intermediate and drain relays. It automatically closes a drainage bond between a lead-covered underground cable and a power return ground when stray current is picked up by the cable to such an extent as to make some of the sheath positive with respect to its environment. It also opens the bond when the drainage current falls to zero and drainage is no longer required. Two sizes are used capable of draining 200 amperes and 400 amperes, respectively.
Its action is very fast, only .015 second elapsing from the time the control circuit releases until opening of the drainage bond. Separate adjustments are available for setting the voltage at which the switch closes and opens the drainage bond.
A capacitive voltage booster enables switch operation over longer battery power supply wires than is possible if the booster is not used. A power supply unit consisting of a stepdown transformer and selenium rectifier is also available to operate the switch with power drawn from an AC power source if the switch must be installed beyond reach of the battery power.
A sealed steel housing enables the switch to withstand submersion and permits installation in very damp locations.
