Cathodic Protection Systems

A cathodic protection transformer rectifier converts an AC supply into controlled DC current and drives it into a buried structure through an anode bed, holding the structure negative with respect to its surroundings so that it does not corrode. Pipelines, tank bottoms, well heads and buried plant piping all depend on one running continuously and at the correct output.

What separates a good unit from a cheap one is everything around the rectifier stack. A properly built TR unit carries MOVs on the input for overvoltage protection, line filters and surge protection devices so it does not push harmonic noise back into the supply, and a control loop that will hold either constant voltage with a current limit or constant current with a voltage limit. Half-cell control, GPS-synchronised current interruption and a remote monitoring unit are what allow the system to be surveyed and managed rather than merely energised. Cheap units skip the filters and the MOVs, and skip the interrupter — which is the point at which on/off potential surveys stop returning usable readings.

We build with the full set fitted rather than offered: integral instrumentation, MOVs, line filters, SPDs, current interrupters and remote monitoring units, engineered against worst-case input conditions rather than nominal ones.

To quote, we need your input line voltage and how far it swings, the output voltage and current required and the ripple you can accept, the number of channels, and the ingress rating the enclosure must meet.

Air or oil cooling only becomes a real decision at higher currents. Forced air falls behind as power rises, and where an IP-65 enclosure is specified, oil immersion is almost always the right answer.