Merlin XT6 Rectifier Monitor by Abriox

Mounted Externally to the Rectifier. Uses Satellite Communication so Requires View of the Open Sky.


MERLIN XT is a compact, durable field unit that monitors the operation of a rectifier and transmits data using satellite communication. It is designed for use in areas where no cellular service is available.

MERLIN XT monitors carry out the functional checks of rectifier output (voltage and current) required in order to ensure a continuous CP supply to the pipeline and to comply with regulatory guidelines. Because they are usually deployed in remote locations, they will very quickly repay their capital cost when compared to monthly manual checks.

MERLIN XT checks that the rectifier remains powered by its external electrical supply (including from a solar station or wind turbine). If the power fails, an alarm is transmitted immediately and its internal batteries take over monitoring for up to 2 years.

MERLIN XT controls an external relay, allowing synchronized interruption cycles to be started and stopped directly from iCPSM web software. It can also monitor ON and OFF potentials at the pipeline.

Installation is quick and fully automatic. Data is transmitted to the system HQ, where it is accessed online using Abriox’s iCPSM web interface. Users can configure and control MERLIN monitors, take on-demand readings, view rectifier CP data in graphical and numerical formats or export data for further analysis and archiving.

MERLIN XT can be seamlessly integrated with cellular MERLIN monitors for a total rectifier monitoring solution.



  • Full global coverage
  • Integrates with MERLIN cellular rectifier monitors for the most economic total network solution
  • Alarms when protection inadequate or power fails at rectifier
  • Eliminates cost of routine monthly measurements at very remote locations
  • Technicians’ travel time freed for data interpretation and follow-up
  • Improves health and safety risks
  • Zero carbon footprint for CP monitoring



  • Hourly check on all rectifier channels
  • Immediate alarm generation (user preset thresholds on all channels)
  • Weekly report with min, max and average of all parameters for the week
  • Control of rectifier output relay for remote synchronized interruption
  • Pipeline locate feature (offered on MERLIN XT Excel)
  • AC powered (110V to 230V) with 2-year battery backup
  • DC power option for solar station or wind turbine
  • Robust lightning protection
  • IP65 ingress protection
  • Wide operating temperature for all extremes
  • Fully automatic test and set up (no laptop required)
  • Fast messaging (typically less than 1 minute) via satellite meshed constellation
  • Web control with graphical/tabular displays and data export


User Alerts

Synchronized Interruption

User Alerts
User-settable high and low alarm thresholds for all measurement channels.
Synchronized InterruptionControl output to drive (optional) external relay for OFF potential measurement, interruption or to switch off the CP output.

Electrical Supply Monitoring

Health and Safety
AC Power MonitoringAlarm generated if power supply fails – so that protection can quickly be restored to the pipeline (MERLIN backup batteries last for 2 years).
Health and SafetyNo risk assessments or lone worker issues at hazardous sites. Protects technicians from exposure to voltages and currents.

On Demand Readings

Custom Reports
On Demand ReadingsReal-time readings can be requested via software and/or from a cellphone in the field. Custom ReportsData automatically archived and presented in custom report formats or exported to other standard applications.


Cost Reduction
EnviromentalEliminates the impact of emissions from survey vehicles, saves thousands of driving miles per month, zero carbon footprint. Cost ReductionAchieves rapid financial payback on the huge cost of taking frequent manual measurements

Satellite Communications

Health and Safety

Satellite Communications

Global satellite coverage ensures reliable communications anywhere in the world.

Health and SafetyNo risk assessments or lone worker issues at hazardous sites. Protects technicians from exposure to voltages and currents.

Diagnostic Mode

Battery backup

Diagnostic Mode

Diagnostic (hourly readings) mode for problem- solving for short periods.

 Battery Backup2 year operation in the event of a power failure.

GPS Synchronization


GPS Synchronization

An 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.

 Weight 3.9Kg (8.5lb)

Operational Temperatures

IP Rating

 Operational Temperatures-35°C to +70°C (-31°F to +158°F). 100% condensing humidity.

IP Rating

The MERLIN XT is IP65 rated. Offering protection against falling dirt, rain, sleet, snow, windblown dust, splashing and hose-directed water.

Lightning Protection

Daily or Weekly Reports

 Lightning ProtectionSurge protection on all external inputs and outputs. 2,500A at 3,000V (8/20us). Additional protection using recommended surge arrestors.  Daily or Weekly ReportsCustom reporting periods allow daily or weekly reporting.

Lightning Protection

Testing performed on the new MERLIN design showed that:

  • A “naked” MERLIN easily survives 2500A at 3kV (8/20us pulse) via AC or from the pipeline – a substantial surge.
  • With Abriox’s recommended external surge arrestors in place, the MERLIN withstands10kA, 10kV without damage - a massive surge.
  •  Even bigger surges (29kA) can be survived by MERLIN - but the external surge arrestors may be blown to pieces

Technical Specification

Physical Dimensions
(H x W x D)

12.4” x 8.5” x 6.8”



IP Rating


Operating Temperature

-31°F to +158°F 100% condensing humidity

Lightning Protection

Surge protection on all external inputs and outputs

2,500A at 3,000V (8/20us)

Additional protection using recommended arrestors

Backup Battery

2-year life, replaceable batteries


Satellite via meshed constellation

Software Management

iCPSM (web based) or CPSM (PC based)

  • Rectifier AC supply (indirectly)
  • Rectifier output voltage 0 to 150V DC 0.1V resolution
  • Rectifier output current (using shunt) ± 100mV DC 0.01mV resolution
    • ± 4V DC with AC rejection
    • 1mV resolution
    • 10 MOhm input impedance
  • ON potential of the pipe
  •  OFF potential of the pipe (using optional relay)
  • Fail-safe relay drive, 0.43A maximum at 12V DC nominal
  • Interruption drive, 0.43A maximum at 12V DC nominal
  • Output patterns from 1s to 60s with 0.1s resolution
  • Short circuit and surge protection
  • Synchronization error less than 1ms

As well as monitoring voltage/current output and checking the external electrical supply to the rectifier, MERLIN XT takes CP measurements (ON and OFF potentials) and can be remotely synchronized with other MERLIN (cellular or satellite) units on a pipeline for CIS (Close Interval Surveys) or DCVG (Direct Current Voltage Gradient) surveys.



The MERLIN XT Excel model additionally controls a solid state Interrupter to provide a signal for tracing the pipeline route.

Select from 2 models:










2nd Current







XT Super


XT Excel



For areas of the world where there is no GSM coverage, the MERLIN XT Transformer Rectifier Monitor offers 100% global satellite communication.

Abriox selected the Iridium system for its high performance and high integrity. Among its many advantages over other satellite systems are:

Satellite Communications

  • Compact antenna
  • No satellite antenna alignment concerns
  • Low power consumption
  • Large data packets
  • Low, uniform, message latency

The last point here is very important - some satellite systems can take up to an hour to send/receive a message if the system is busy, Iridium is 20 sec to 2 minutes (maximum). This is because the Iridium meshed constellation relays data from satellite to satellite without touching ground until it is downlinked at an Iridium gateway.

This means the MERLIN XT can be very quickly installed with negligible waiting time – a huge advantage to our customers.