detection devices

No fault goes unnoticed!

AQ-50 – Detecting even high-impedance earth faults in distribution networks

The AQ-50 fault detection devices leave no fault in distribution networks unnoticed! With their superior capability to detect even the most challenging faults like high-impedance and intermittent earth faults, AQ-50 devices deliver accuracy you can rely on. The unique algorithm analyzes changes to phase currents during an earth fault, which enables the detecting of faults with a fault current as low as 0.5 A. The algorithm also makes AQ-50 devices applicable to any type of cable or overhead line distribution network (compensated, isolated, or directly earthed).

Impedance earth fault

Cost-efficient fault detection

Our AQ-50 devices are powerful and yet cost-efficient compared to other fault detection technologies, because their fault detection is based on the measurement of only phase currents. This saves space and reduces cost significantly as separate voltage measurements (polarizing voltage) are not needed; this also makes the AQ-50 devices easy to fit in new and retrofit installations!

AQ-50 fault detection devices also feature an integrated disturbance recorder function that supports COMTRADE format. It records currents and events of the last detected faults, and the recordings can be downloaded using the integrated Web interface for detailed off-line analysis.

Automating the entire power distribution network

AQ-50 is truly powerful. In addition to the fault detection functionality for up to six feeders per device, AQ-50 devices are mini-RTUs equipped with Ethernet-based communication. This allows for the automation of the entire power distribution network with a single device: you can control and monitor switching devices, and have a fully automated fault location, isolation, and service restoration (FLISR).

More and more secondary substations are being equipped with disconnectors and circuit breakers. By including AQ-50 devices that provide RTU functionality and sensitivity of protection relays in your secondary substations today, you can bring your distribution network to the next level when the time is right for you.

Proven technology

AQ-50 devices originate from innovative Protrol fault detection technology which has now been integrated into Arcteq Relays. AQ-50 has therefore inherited 20 years of development and has a successful track record of more than 40,000 devices installed.

Offering industry-leading customer service

We are an independent, family-owned company with a focus on protection relays and arc flash protection systems. We are an agile companion with reliable delivery times, and all our products are manufactured in our headquarters in Vaasa, Finland. We operate with the best local partners, with whom we can guarantee transparency and flexibility throughout the entire process.

About us:

  • Over 50,000 protection devices and 100,000 arc flash sensors installed in more than 50 countries all over the globe.
  • Sales and support in continents through our own offices and through partners around the world.
  • One of the fastest growing companies in global protection and control business.
  • Part of Ensto Group, an international family business, bound by a common purpose: making better life with electricity. Sustainably.

We invest heavily in continuous research and product development to address the challenges raised by the changes in power grid technology and sustainable energy systems. Our mission is to help enable the safe and reliable supply of energy by enhancing power system protection.

In addition to high-quality products we are committed to providing our customers industry-leading support and service. Our average after-sales response time is under two hours. We can also offer a quick response to development requests – with us three years can be cut down to one.


Read more about what others have achieved with our products in our references below.

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Arcteq protects Taiwan’s longest tunnel

Arcteq’s scope of supply includes busbar protection, three winding transformer protection, and Feeder protection IEDs to protect, control, and provide accurate measurements on the tunnel’s power distribution feeders.

Want to know more?

Do you want to hear more about the possibilities of our fault detection products? Contact our sales team or ask us for an offer. We will get back to you by the next working day at the latest.



Happy Holidays!

It’s that time of the year again…as the year is coming to its end, we would like to thank you, our customers and partners, for supporting us and for making power distribution safer and more reliable around the world. Let’s let the closeness of family and friends renew our spirits this festive season.

From all of us at Arcteq we wish you the very best during the holiday season and beyond.