The operation of transformer rectifiers (electrical units that place a voltage onto the pipeline to counteract the electrolytic corrosion reaction) is critical to cathodic protection. The voltage must be applied consistently and at the correct level:
- Too low – and the pipeline will be insufficiently protected
- Too high – and the pipeline may become brittle
Pipeline operators are recommended to check the correct functioning of their rectifiers at monthly intervals.
To be allowed to carry out functional rectifier checks, CP technicians must be trained on different electrical systems (AC supply and DC output) and many rectifier sites are remote and difficult to access.
Rectifier measurements are taken automatically by a MERLIN Transformer Rectifier Monitor installed at the rectifier. This checks that the electrical supply is still present, monitors the voltage and current output and (optionally) can take ON and OFF potential measurements at the rectifier drain point.
In order to provide reliable communications anywhere in the world, MERLIN rectifier monitors use two different types of communication, 3G/2G and Satellite. Regardless of the type of rectifier monitor or communication, all data is automatically transmitted in a management report to the system HQ where it is displayed and archived in Abriox’s MERLIN CPSM software or online via iCPSM.
Because they report to a common software platform, different rectifier monitor types can be mixed together in the same network.