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Holt Systems

Cathodic protection monitoring: know the day a rectifier stops

We fit a node to each CP rectifier on your corridor and text your phone when output current stops.

  • MeasuresRectifier volts, amps, supply
  • AlertSMS when output current stops
  • Works withoutMains or mobile at the cabinet
Get a quote for CP monitoring See the SMS alerts or call 07 2150 3666
Cathodic protection monitoring along a pipeline corridor Plan view of a remote mine or CSG steel pipeline corridor. A solar CP unit cabinet with an output shunt is fed by a buried anode bed on its left and connects by a negative cable to the steel pipeline, which has test points along it. A LoRaWAN node with an antenna sits outside the cabinet and sends readings by radio to a gateway on the plant mast. The gateway reports by Starlink backhaul to a phone showing a no-output-current alarm. A dashed ring around the corridor marks the monthly drive-around route that monitoring can reduce. LoRaWAN gateway on plant mast Starlink backhaul to SMS, dashboard Alarm No output current LoRaWAN radio Buried anode bed Solar CP unit output shunt LoRaWAN node outside cabinet Test point Test point Steel pipeline Monthly drive-around route
Plan view of a pipeline corridor: a solar CP unit with an output shunt, a node outside the cabinet, the buried anode bed and the steel line with test points, with a plant mast gateway on Starlink sending to a phone showing a no-current alarm.

A tripped rectifier can sit dead for a month

Cathodic protection monitoring answers one question between visits: is the rectifier still pushing current to the steel? Most mine and CSG sites find out by driving to each cabinet and reading a meter.

If a fuse, breaker or cable fails the day after the visit, the pipe is unprotected until the next drive-around. Nobody knows.

The cabinet meter only shows right now. A slow rise in voltage from an ageing anode bed never gets written down.

  • Solar CP units out along the corridor have no mains to tell you they've lost supply.
  • Wet-season floods can cut the track to a cabinet for days.

How cathodic protection monitoring works along your corridor

  1. 1

    A shunt and tap read the output

    We read output voltage across the terminals and output current from a calibrated shunt, using the cabinet's own shunt where there is one.

  2. 2

    A node outside the cabinet sends it

    The cabinet's a metal box, so the antenna sits outside.

  3. 3

    A gateway on the plant mast catches it

    It covers cabinets in line of sight and reports by Starlink or 4G. A solar gateway can reach cabinets further out.

  4. 4

    You get the alert

    Output current below about 5 percent of setpoint for 2 readings sends an SMS to the people you name.

CP alerts

  1. Fri 6:40 am

    CP unit 3 still at 0.2 A after 4 h. Not acknowledged. Escalating to maintenance lead.

  2. Fri 9:30 am

    CP unit 3 output back to 12 A, 14.2 V. Loss of output lasted 7 h.

What lands on your phone when output stops

We set alert values from your CP specialist's commissioning record.

CP alerts

  1. Fri 2:40 am

    CP unit 3 output current 0.2 A, setpoint 12 A, for 2 readings. Solar battery 11.1 V. Protection is off. Check supply and fuse.

  2. Fri 6:40 am

    CP unit 3 still at 0.2 A after 4 h. Not acknowledged. Escalating to maintenance lead.

  3. Fri 9:30 am

    CP unit 3 output back to 12 A, 14.2 V. Loss of output lasted 7 h.

Messages go to the people you nominate, by SMS to any phone.

CP unit 3, output current

Dashboard view

Output current
12.0 A
Output voltage
14.2 V
Solar battery
12.6 V
0.2 6.1 12 Alert below 0.6 A Thu 6 amThu 6 pmFri 2 amFri 6 amFri 10 am A
Example readings for illustration.

What we fit to each CP unit

Your CP specialist confirms the measurement points first. We don't touch the protection settings.

  • LoRaWAN node outside the cabinet

    Takes the voltage and shunt readings and sends them by radio. The antenna sits outside the metal cabinet.

    Reads every 5 to 15 min

  • Isolated voltage input and shunt

    Reads DC output volts, and output amps from a calibrated shunt in the output.

    Sized to the unit's rating

  • Supply and battery input

    Watches a mains relay, or the battery voltage on a solar CP unit, so you know why output stopped.

    Alert on supply loss

  • Gateway on the plant mast

    Collects readings from every cabinet in range and passes them on.

    Several km in open country

  • Starlink or 4G backhaul

    Gets the readings to your phone where the cabinet has no mobile coverage.

    No wifi or cable needed

The same trip, with and without a node on the rectifier

Without monitoring

  1. Day 1Fuse blows after a storm. Output drops to zero.
  2. Day 2Nothing on any screen. The steel is unprotected.
  3. Day 20Still nobody knows. The creek is up and the track's shut.
  4. Day 30Monthly check finds the cabinet dead.

With monitoring

  1. Day 1, 2:10 amFuse blows. Output current falls to zero.
  2. Day 1, 2:40 amTwo low readings. Your phone buzzes.
  3. Day 1, 9 amYour sparky swaps the fuse.
  4. Day 1, 9:30 amOutput is back. The dashboard shows it.

A monthly meter reading versus a reading every 15 minutes

TopicTodayWith monitoring
A rectifier tripsFound at the next drive-aroundSMS within about 30 minutes
HistoryOnly what's on the meter nowVolts and amps on a trend line
Slow anode bed decayMissed, no recordLoop resistance trend shows it

Cathodic protection monitoring on a mine or CSG lease

Out in the Bowen and Surat basins, a lot of rectifiers are solar CP units with no mains. CSG gathering lines are mostly polyethylene, the Australian Pipelines and Gas Association says, so the nodes go on steel transmission lines, risers and plant steelwork.

Solar CP units run off a panel and battery. Off grid solar monitoring covers the same kit on wellsite RTUs and comms huts.

Storms hit rectifier electronics hard. See mine site surge protection for a board that reports its own failure. Cabinets out on a lease also get cut into, so look at well site cable theft alerts.

Steel legs and tank of a water tower seen from below
Illustrative photo. Photo: Pexels

What cathodic protection monitoring costs

We set a fixed price after a short scoping call or site visit. It depends on how many cabinets, how far they are from a gateway, and the backhaul. After handover, ongoing support is available as a plan.

Get a quote for CP monitoring

The fixed price covers

  • Nodes, shunts, taps and supply inputs
  • Gateway and Starlink or 4G backhaul
  • Installation and electrical work under licence 1513082
  • Alert set-up and commissioning against the cabinet meter
  • Ongoing support plan: battery and sensor replacement, fault fixing, alert tuning, more cabinets as you add them

What this won't do

  • It reads and reports. It doesn't adjust or switch the rectifier, and it's not a control system.
  • Normal output doesn't prove the steel is protected. Coating damage and interference can still leave it exposed.
  • Surveys, interference testing and registration stay with your CP specialist. We don't design cathodic protection systems.

With you every step

Every corridor is different, so we walk it with your maintenance lead and CP specialist before anything is ordered.

  1. 1

    Discovery

    We walk the corridor, list each rectifier and its rated output, and test the radio path to every cabinet.

  2. 2

    Design

    You get a fixed-price proposal covering nodes, gateway, backhaul, electrical work and alert rules from your commissioning records.

  3. 3

    Build and test

    We build and bench-test the nodes, gateway and alerts in the workshop before anything goes to site.

  4. 4

    Install and commission

    Our licensed electricians fit the shunts, taps and nodes, then check each reading against the cabinet meter.

  5. 5

    Ongoing support

    We hand over, run a trial beside your manual checks, tune the alerts and stay on for ongoing support.

Why Holt Systems

We design, install and commission every system ourselves, then look after it with an ongoing support plan. Monitoring supplements the site's own control, protection, fire and safety systems; it does not replace them.

Alerts
SMS to any phone, no app
Based in
Brisbane, QLD
Electrical licence
QLD 1513082
After install
Ongoing support plans
Call
07 2150 3666

Cathodic protection monitoring questions

Do we need to register our cathodic protection system?

WorkSafe Queensland describes registration for any system able to deliver more than 0.25 A, with testing and records kept by the owner. Monitoring doesn't change those duties. Check with your CP specialist or the Electrical Safety Office whether adding a device to a registered rectifier needs notifying first.

Does remote monitoring replace the annual survey?

No. Potential surveys, interference testing and structure inspections stay with your CP specialist. Rectifier volts and amps show the unit is delivering output, not that the steel is protected. Monitoring fills the gap between visits and gives your specialist a continuous output record.

What if a rectifier is outside gateway range?

Readings stop outside range, so we test the path to every cabinet at the site visit. A rectifier far down the corridor can get its own solar gateway on an existing pole or tower. If nothing's in reach, a cellular or satellite CP logger may suit better.

Can we cut back the monthly rectifier check?

Maybe, but that's your call with your CP specialist. We suggest a trial of 4 to 8 weeks beside the manual check, comparing node readings with the cabinet meter. Only reduce checks if your specialist agrees.

Who works inside the rectifier cabinet?

Our licensed electricians, under QLD Electrical Contractor Licence 1513082, once your CP specialist confirms the measurement points. We isolate and prove dead, fit the shunt and taps, then test and record. We don't change the commissioned protection path or settings.

Sources

  1. Cathodic protection systems, WorkSafe Queensland
  2. APGA Code of Practice companion paper CP-11-004 Safety in Operations, Australian Pipelines and Gas Association
  3. Minister releases full report into Varanus Island gas pipeline explosion, Government of Western Australia
  4. Curragh Mine Coal Tank Corrosion Prevention, hybrid cathodic protection, Infracorr Consulting

Get a quote for CP monitoring

Tell us what you need to watch and where. We confirm the sensors, gateway location and alert recipients, then give you a fixed price.

Or email hello@holtsystems.com.au

Your details are handled in accordance with our privacy policy.

  1. 1

    Tell us about the site

    A few lines on the assets, distances and what you need to know about.

  2. 2

    A call to scope it

    We confirm the sensors, gateway location and alert recipients, and whether a site visit is needed.

  3. 3

    Fixed price

    You receive a defined scope and a fixed price before any work starts.

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