A protective device installed between a cathodically protected structure and a grounding system, such as across insulating joints or to mitigation wire for AC interference. It blocks DC below a set threshold, commonly around -2/+2 V, so CP current stays on the pipe, while conducting induced AC, lightning and fault current to ground to protect people and coatings. Polarization cells, a wet electrolytic device, do the same job.
Line runs parallel to a 500 kV corridor, tie it to the zinc ribbon through a decoupler.
Also heard as
- solid-state decoupler
- SSD
- DC decoupler
Related terms
Insulating joint
Fitting that electrically isolates one pipe section from another so CP current stays where it belongs.
Interference
Unwanted DC or AC current picked up from another source, which corrodes a structure where it leaves.
Bond
Wire or cable connection that ties two metal structures together electrically, often to control CP current.