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Established in Chicago in 1927, Littelfuse is synonymous with innovation. Incorporating the Startco Engineering (Canada) business in 2012, Littelfuse have become a global leader in Protection Relay and Control products including motor & pump protection relays, arc-flash relays, ground fault relays, feeder protection, pump controllers, time delay relays, flashers and tower lighting. Professionals in construction, manufacturing, mining, oil & gas, solar, and many more industries rely on Littelfuse for rugged, lasting protection for their designs and critical applications.

From humble beginnings in 1969, Stemar Electrical Products has grown to become a leading Australian manufacturer of Instrument transformers, Dry type transformers and underground distribution equipment. Respected for their advanced design systems, Stemar also solutions for Neutral Earthing Transformer cubicles, CT’s and fit outs for dead tank circuit breakers.

Featured Case Study

Littelfuse Arc-Flash Relay Saves Plant from Catastrophic Damage

Tim Deschamp from Evans Enterprises, Tulsa, Oklahoma, was working with a customer to help them resolve and reduce a critical issue with an electrical hazard in their furnace control room. An earlier arc-flash analysis had determined that one 480-volt cabinet, which was fed from a 3500 kVA transformer, exceeded an arc-flash Hazard Risk Category 4 (HRC).

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Different brands

Our brands are carefully selected and have a great track record of quality, reliability and safety.

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Years of experience

Since being established in 1996, our company has been synonymous with great customer service.

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Customers served daily

Fuseco has strong relationships with many clients from a wide range of industries.

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Knowledge Centre

The Dugald River Zinc Mine, located in the north-west of Cloncurry in Northern Queensland, and owned by MMG, had Neutral Earthing Resistor’s installed on site and they were doing annual periodic maintenance checks to verify NER resistance and integrity during shutdowns.
A motor protection relay is designed to help protect motors from overloads, jams, phase loss or unbalance, heat, heavy start-ups or excessive operational cycles.
Clever yet very simple and cost-effective steps can be taken today, to improve the electrical safety of old switchboards in use across the country, lacking modern protection against arc-fault events.
The Littelfuse EL731 series is a new and sensitive Earth Leakage Technology – the first of its kind to offer complete coverage of all frequencies from 0(DC) to 6,000Hz, including DC earth leakage typical for VSD applications.
Had this relay not been there, they were looking at between $800,000 to $1 million in damages.
A Neutral Earthing Resistor (NER) plays an important role in an electrical environment and is one of the most effective ways to maximise personnel safety. Continual monitoring is imperative to detect resistor failure with or without an earth fault present.
The MP8000 dramatically increases motor protection, resulting in longer motor life plus reduced downtime and repair costs.
Protect your People. Protect your Equipment.
Littelfuse Protection Relay and Arc-Flash FAQ
Littelfuse White Paper -Key Considerations for selecting-Arc-Flash
Littelfuse Protection Relays AF0100 Generator Application Guide
Littelfuse PGR-8800 Application Guide
Littelfuse AF-0500 Application Guide
Littelfuse Diagram -Protect Your Wind Turbine From Arc-Flash hazards
A new approach to mining earth leakage protection with medium voltage drives

Top FAQs

A protection relay is a device that receives inputs typically from current transformers CT’s (but can be other sources) and then compares these inputs to set levels. If these inputs exceed the set levels a protection relay can then provide that information via display or indication, feed that information to other electronic control devices or it can be connected to a circuit breaker to isolate power.

Yes, currently Fuseco can offer both earth leakage and NER relays that are compliant to AS2081:2011. The relay manufacturer (Littelfuse) is also currently in the final stages of development for an AS2081:2011 compliant continuity relay that we expect to release in the near term.

An arc fault is a type of electrical fault that results from the breakdown of an insulating medium between two conductors where the energy is enough to sustain an arc across the insulator (often air) and can cause extreme amounts of light (arc flash), immense heat upwards of 19,000 degrees, and a resulting explosive pressure wave (arc blast). By using a relay that has optical sensors we can detect the flash of light the emanates from an Arc Flash and within 1 msec send a signal to a breaker to interrupt power. Because of the immense energy being released by an Arc Flash reaction time is critical. It can be seen on the graph that with a relay reaction time of only 1 msec (+ circuit breaker reaction time) we can interrupt power before the Arc Flash can result in critical damage.

An arc-flash happens when electric current flows through an air gap between conductors. There are several ways this can happen but the most common occurrence is when conductor insulation is worn or broken down.

The most important aspects of arc-flash relays are:


  • reaction time
  • trip reliability
  • ease of installation
  • sensor flexibility
  • software
  • sensor design
  • avoidance of nuisance tripping
  • scalability


To gain a deeper understanding of which features to consider when selecting an arc-flash relay please refer to the downloadable application guides.

Arc-flash relays are a necessary component in an electrical cabinet because they reduce the amount of incident energy in the system. While an arc-flash relay cannot prevent an arc flash from happening, it will protect critical assets and workers’ safety by reducing the severity of the flash. An arc-flash relay is an integral part of an arc-flash protection scheme that can minimize damage, and save money, time, and lives.

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.

An earth fault can occur as a result of inadvertent contact between and energized conductor and earth or equipment frame. There can also be earth leakage from a system without “inadvertent contact”. This type of fault can be called capacitive earth leakage and it is caused by a capacitive effect between a high power conductor and earth. Small amount of earth leakage current can occur as a result of this capacitive effect. Whether it is smaller amounts current from capacitive earth leakage or larger amounts of current from direct inadvertent contact an earth leakage relay can detect this fault current. In all electrical circuits, current returns to its source. An earth fault relay can use a zero sequence CT to monitor phase current to ensure that all current coming from the source returns on those same conductors or it can monitor current in the connection between transformer neutral and earth. By either method the earth leakage relay detect any lost current to earth.

Applicable Industries

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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