Sealing current and its impact on ISDN powering requirements

Sealing current is a low-level DC current that has been used to maintain the transmission quality of certain interoffice and special services circuits by inhibiting corrosion at wire splices. The authors examine the sealing current issue, and discuss the way in which splices degrade through corrosive attack in the service environment. They also discuss the mechanism by which sealing current inhibits this degradation, the use of this understanding in applying sealing current to a subscriber loop, and a low-energy sealing current supply implementation for ISDN (integrated services digital network). While the focus is on the application of sealing current to subscriber loops, the discussion is equally valid in addressing special services circuits and interoffice cables.<>