Arc Protection

Arc Flash Protection

Arcteq AQ 100 series offers a complete solution to arc flash protection. The AQ 100 is designed utilizing the most modern technology with a focus on simplicity while maintaining both flexibility and function. Built to meet the growing demands in both LV and MV switchgear and control-gear applications ranging from basic stand-alone to more complex system solutions.

How does it work?

This short animation shows a basic configuration setup of an arc protection system. This Arcteq system features an AQ110 and 3 AQ101 relays, along with several point sensors. This comprehensive setup will allow for rapid arc detection (just 2 ms). The quick tripping of the circuit breaker will result in less damage from the arc to both equipment and personnel working nearby.

Maximum savety and minimum process downtime

  • Total arc fault clearance time 5 ms with re-usable quenching device
  • Quarter cycle arcing time guarantees low incident energy levels
  • Lower category personal protective equipment (PPE) needed
  • Faster engineering with standard arc schemes
  • Faster commissioning, one button configuration, clear LED signals, no software needed
  • Full product range and optimal price/functionality ratio for any application

Why arc protection?

The main purpose of an arc flash protection is to protect both substation personnel and equipment from the consequences of and arc fault. An arc protection system detects the fault in less than 2 ms and including the delay in the breaker the time for extinguishing the arc is normally less than 70 ms. A normal selective over current protection can have operation times up to 500 ms. In case of an arc fault in a switchgear equipped only with traditional feeder protection, the risk for severe injuries to substation personnel is very high. The ultimate arc protection is the AQ 100 system including a quenching device AQ-1000 or AQ-2000. The ultrafast arc quenching device extinguishes the arc in less than 5 ms. In many cases this provides an alternate regarding more expensive arc resistant gear and a more effective solution to arc flash protection.

Arc flash protection - the new NORMAL in power grid protection

During the last decade the application of arc flash protection based on light sensing has become the new normal in power protection. Arc flash protection provides unquestionable benefits, such as improved speed, selectivity and cost effectiveness. Arc flash protection has been introduced to all continents and applied in all types of electrical power distribution systems ranging from electrical utility to traditional and renewable power generation, industrial, marine, off-shore, institutional and commercial applications in low and medium voltage switchgear and controlgear. Protection relay manufacturers have incorporated arc flash protection features in numerical multifunction protection relays and IEDs. Because of this development, often arc flash protection is considered merely as an additional protection function. This approach has clear shortcomings in appreciating the criticality and complexity of the arc flash protection. Selective and tailored tripping scenarios must be designed in a way that protection operates flawlessly in all scenarios and in any network topology. At the same time, systems are to be designed with a total selectivity limiting the effected zone to minimum in case of an arc fault. Therefore, arc flash protection should not be considered as a protection function but as a protection system.

Benefits of dedicated arc flash protection relays

Dedicated arc flash protection relays are designed to protect against arcing faults only. They operate in parallel with the numerical multifunction protection relays that provide the classical overcurrent-based protection schemes. This approach provides redundant protection and adds on protection dependability. Arcteq’s dedicated arc flash relays require minimal or no customer settings. This is of an essence as studies confirm that up to 85% of the maloperation of the protection is based on wrong settings. Arcteq’s arc flash relays are developed for system approach. Protection operation time is 7 ms for any number of circuit breakers under any operational scenarios. No inherent delays due to communication bus operating times is introduced. This is of the outmost importance when calculating the incident energy levels.

New standards by IEC 60947-9-1:2018 and UL 2748 

The first arc quenching device standards are released for low- voltage applications. Arcteq’s AQ-1000 arc quenching device is tested and listed by the Underwriter’s laboratory as per UL 2748 standard. The AQ-1000 also complies with newly released IEC 60947-9-1:2018 arc quenching device standard.


Trip criterias

The first generations of arc flash protection relays utilized light sensitive arc sensors alone as the tripping criteria. Advances combined arc light and current sensing for the dual sensing method to further increase the reliability of the protection system. However, the traditional current and light-based dual sensing system may overtrip when installed in equipment involving air magnetic circuit breakers. As well in some cases, especially in low voltage systems, the absence of current  transformers makes it practically impossible to apply current criteria in the arc flash protection. Medium voltage switchgear’s incoming cable compartments cannot be protected with light and current if the overcurrent is measured from the protected switchgear.

Applying light and pressure sensor with air cirquit breaker

It is well known that low-voltage air circuit breakers create strong light emission during the breaking sequence under load. Further, when a low-voltage air circuit breaker or air magnetic circuit breaker operates on a downstream fault, its arc chutes create an arcing that may result in activating any arc light sensor installed nearby. Since downstream fault condition typically leads to exceeding of set overcurrent trip level, both light and current conditions may be fulfilled simultaneously and consequently the dual sensing arc flash protection system based on light and overcurrent may cause a nuisance trip of the incoming feeder circuit breaker. Adding arc flash pressure sensor into the schemes involving air circuit breakers provides for additional trip criteria that will not be fulfilled in an event of normal circuit breaker operations and one can easily prevent potential nuisance trips. Using Arcteq’s AQ-02 arc flash sensor combining arc light and pressure sensing in a single enclosure, a dual sensing system is achieved in a convenient and easy to install solution. If applying an overcurrent sensing into the system, even a triple sensing system based on current & light & pressure trip criteria can be utilized.