Test Station


The MERLIN CP Monitor is a compact unit housed within a Test Post. It collects Cathodic Protection (CP) data and communicates (via either an internal or external antenna) using the GSM network.

MERLIN CP monitors collect CP data automatically, checks the measurements against specified alert criteria and reports immediately if an alarm threshold is exceeded. They can be deployed anywhere on the pipeline network where it is important to record ON/OFF pipe-to-soil potentials, native coupon potentials and measurements of bonding or interfering currents.

Alternatively it may simply be that certain measurement points on the pipeline create risks to CP technicians, such as at busy road or rail crossings, or are difficult to access, such as on private land. At these points remote monitoring is very cost-efficient and can improve safety.

Two key features of the Abriox system are:

  • Set-up from a mobile phone using text messaging
  • AC monitoring to identify a possible corrosion threat and protect the workforce from dangerous voltages or currents.

All data is automatically transmitted in a management report to the system HQ where it is available on-line using Abriox’s MERLIN iCPSM software.

iCPSM provides access from any Internet-enabled PC to a passwordprotected CP database, unique to each customer. Users can configure and control MERLIN monitors, view CP data in graphical and numerical formats or export data for further analysis and archiving. Alternatively, Abriox’s
CPSM PC-based software provides the same functionality.



  • ON / OFF / Native Potentials and coupon current monitoring channels
  • Compact size - quick and easy to install, typically 20 minutes on site
  • Daily CP level check (hourly optional for problem solving)
  • Alarms reported immediately (user preset thresholds for all channels)
  • Weekly report gives min, max and average of all channels for the week
  • 5-year life, batteries replaceable
  • Sealed, weatherproof unit with robust lightning protection and wide operational temperature for all extremes
  • Test and set-up from mobile phone using text messaging
  • Web-based or PC-based user interfaces with graphical/tabular displays and data export



  • DC and AC monitoring for full corrosion prevention
  • Fully automatic system - data sent in automatically, wirelessly
  • Email or text message alarm when CP levels are inadequate
  • Reduced cost of measurement
  • Engineering time freed up for data interpretation and follow-up
  • Reduced risk to workforce at dangerous or remote sites
  • Zero carbon footprint for CP monitoring - no vehicle surveys required
  • Small size for deployment inside test posts


Technical Specification


  • DC Potential
    • 10 MOhm input impedance
    • ± 4V DC with AC rejection
    • 1mV resolution
  • AC
    • 0-70V AC RMS, 10mV resolution
  • Current shunt
    • 0-100mV
    • 0.01mV resolution
    • AC and DC measured
  • All monitoring channels are fully independent


  • Pair of relay contacts, normally closed
  • Contacts open to take instant OFF
  • Contacts rated at 1A at 30V DC

Physical Dimensions (H x W x D)
      - 125mm x 85mm x 55mm
      - 450g
IP Rating
      - IP67
Operating Temperature
      -40°C to +85°C 100% condensing humidity
Lightning Protection
      - Surge protection on all external inputs and outputs 2,500A at 3,000V (8/20us)
      - 5-year life, replaceable battery module
      - GSM/SMS
Software Management
      - iCPSM (web-based) or CPSM (PC-based)

Select model according to the monitoring channels required:

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