Dugald River Zinc Mine

The Dugald River zinc-lead-silver mine is situated 65km north-west of Cloncurry in Northern Queensland, Australia, and owned by MMG. It is one of the world’s biggest zinc-lead-silver deposits and comprises of high-grade minerals. Dugald River ore is mined underground using diamond drilling techniques, after which it is extracted to the surface and treated on-site. Concentrate is then transported to the Port of Townsville via rail departing from Cloncurry.

Dugald River Zinc Mine

The Dugald River zinc-lead-silver mine is situated 65km north-west of Cloncurry in Northern Queensland, Australia, and owned by MMG. It is one of the world’s biggest zinc-lead-silver deposits and comprises of high-grade minerals. Dugald River ore is mined underground using diamond drilling techniques, after which it is extracted to the surface and treated on-site. Concentrate is then transported to the Port of Townsville via rail departing from Cloncurry.

The Challenge

The mine had NER’s installed on site and they were doing annual periodic maintenance checks to verify NER resistance and integrity during shutdowns.  They had identified that with this type of testing you can only be confident of the NER integrity at the time you check.  The NER can fail at anytime after a check and before the next but you will not be aware of the failure. This was of concern to the Electrical Engineers on site and the Fuseco team were engaged to provide some advice.

What is a Neutral Earthing Resistor (NER) Monitor?

Three phase power systems are most often solidly earthed, however by using a Neutral Earthing Resistor (NER) a power system can be resistance earthed. This is done so that if an earth fault were to occur the amount of fault current will be limited by the NER resistance. One potential problem with a resistance earthed system is; what happens if the NER goes open circuit due to damage? If this were to happen the power system has now changed from a resistance earthed system to a system with no earth reference (floating). Now the NER is no longer restricting the amount of fault current and other devices that rely on an earth reference in order to operate, cannot do so. By using a NER monitoring relay the resistance and integrity of a NER can be continually monitored to detect for any variance in the NER resistance or integrity.

  • The SE-330AU NER integrity function complies with AS/NZS 2081.8.2011. 
  • Outputs include four relay outputs, and an analog output. 
  • A mini USB port is included to view measured values, configure settings, and check event records. 
  • An on-board micro SD card can be used for long-term data logging. 
  • Network communications options are available. 
  • For non-AS/NZS 2081 applications, see the SE-330 or SE-330HV.

The Solution

Fuseco recommended the installation of a SE-330AU relay that can continually monitor NER integrity and if any NER failure occurs the relay will detect this immediately. The SE-330AU is an advanced earth-fault and earthing-resistor monitoring relay for low- and medium-voltage transformers and generators. It monitors neutral current, neutral-to-earth voltage, and neutral-to-earth resistance. It provides continuous monitoring of the neutral-to-earth path to verify that the neutral earthing resistor (NER) is intact. This is of utmost importance— an open NER renders current-sensing earth-fault protection inoperative and could result in a false belief that the system is functioning properly.

The Outcome

By having a relay that is checking NER integrity 100% of the time there was no need for annual checks that were time consuming and not effective. The Dugald Zinc Mine Engineering team were very happy to replace manual checks with a relay solution.


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Hi Tim, just wanted to thank you and the Fuseco team for your help. You've managed to help us solve some nagging issues here and the Littelfuse SE-330AU relay installation has saved us a lot of time. Thanks!

Mark Sherman

PGS Silver, Queensland

Just wanted to send a note of thanks to you guys. When it comes to relays, your advice & service is high level & appreciated. Cheers.

Jesse Marshall

Newcrest WA

The Littelfuse SE-701 & the CT's are functioning well. Thanks guys, really appreciate your help. Good to work with people you can rely on.

Cliff Peligro

Alpha Coal, Queensland

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