Rectifier and Solar Station Monitors

///Rectifier and Solar Station Monitors
Rectifier and Solar Station Monitors 2017-06-14T19:26:38+00:00

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.

MERLIN DX Transformer Rectifier Monitors (3G/2G)

MERLIN XT Transformer Rectifier Monitors (Satellite)

MERLIN XT Transformer Rectifier Monitors are durable field units that monitor the operation of a rectifier or solar station. They are designed for remote areas where 3G/2G coverage is inadequate but can be integrated with 3G/2G-based MERLIN units for a total network monitoring solution. MERLIN XT Transformer Rectifier Monitors are mounted externally to the rectifier or solar station. These model’s use satellite communications and have an internal antenna; therefore they require a view of the open sky.

Download the datasheets for the MERLIN Transformer Rectifier Monitors and our other products from our support section


MERLIN rectifier (including solar station) monitors have been designed to carry out the functional checks of rectifier output (voltage and current) required in order to comply with regulatory guidelines. They will quickly repay their capital cost when compared to manual monthly checks.

However, MERLIN rectifier monitors ensure continuous protection of the pipeline:

  • They will alert the user immediately when a power failure to the rectifier has been detected (and will also report when it has been restored). They have a built-in 2-3 year back-up battery so that they will continue to monitor rectifier output and report normally even during a prolonged power outage.
  • High and low alarms can be set on the rectifier output channels. These will detect a rectifier failure independently from the electrical power supply. For example, a lightning strike may cause the rectifier fuse to blow - the power supply will still be present but the rectifier output will rapidly drop away, leaving the pipeline unprotected.

Enhanced models offer additional CP measurements (ON and OFF potentials) as well as the facility to synchronize remotely with other rectifiers on a pipeline for Close Interval or DCVG (Direct Current Voltage Gradient) survey measurements in the field. Pipe-to-soil potential measurements at the rectifier require a reference cell and relay. Remote synchronization requires a MERLIN solid state Interrupter. Premium, Super and Excel GSM models and the MERLIN XT Super can be selected to monitor either a 2nd Rectifier Current output OR the ON/OFF Potential.

Remote Synchronized Interruption

This feature (available on Super and Excel models) enables rectifiers on the same pipeline to synchronize their output and interrupt it according to a precise timing interval.

An optional on-board GPS module enables precise time synchronization of all MERLIN monitors on a pipeline. It also provides a link to mapping software for accurate positioning. Compatible with all industry recognised Close Interval and DCVG survey patterns and most portable above-ground survey equipment.

Interruption may be switched on and off, or the cycle changed, from a cell/mobile phone in the field (GSM versions only), from the CPSM software or online via iCPSM.

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Pipeline Locate

MERLIN is primarily designed to provide remote monitoring of cathodic protection. However, because it controls an Interrupter, it can switch or modulate the rectifier’s output current to generate an electromagnetic “pipeline locate” signal that can be traced and pin-pointed using a pipe/cable locator.

This unique feature is particularly useful for gas and petrochemical companies who have a lot of CP installations. The “pipeline locate” signal can be activated from the system software in the office – or from a mobile phone in the field using text messaging. It completely eliminates the laborious set-up time associated with traditional pipeline location equipment – and ensures the locate signal is applied to the correct pipeline!”

The feature is patented and is available on both MERLIN DX & XT EXCEL transformer rectifier monitors.

Database Software

Data from MERLIN Monitors is automatically stored and transmitted in a management report to the system HQ where it is displayed and archived in the MERLIN CPSM software (Desktop application) or accessed on-line via the internet based iCPSM.

Monitors can be configured to send their data to two HQs; changes made at one HQ are automatically updated at the other HQ with a full audit trail of all changes made to the system.

  • CPSM (Cathodic Protection System Manager) - PC based database software package for displaying, archiving and exporting data from MERLIN monitors.
  • iCPSM (Internet-based Cathodic Protection System Manager) - Online database software package for displaying, archiving and exporting data from MERLIN monitors.
Learn More

For user manuals, quick start guides and software updates, please visit the support section

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