Arc faults have the potential to cause severe personal injury, death and excessive damage to infrastructure, which can result in high revenue losses for businesses due to production downtime.

Even in the most modern switchgear assemblies, the risk of an arc fault is imminent, as they can be caused by incorrect installations on switchgear assemblies, contaminants, foreign objects or even the ingress of animals in the switchgear assembly. Within a few milliseconds, an explosion can occur leading to a high amount of energy being released; generating heat, pressure waves and toxic gases.

Switchgear assemblies can be damaged to the point that they need to be completely replaced – a process that can take several weeks. This can cause a great deal of inconvenience, with corresponding severe cost implications as well, if the process takes place on a site that requires a continuous power supply. However, such damage can be substantially minimised if an arc fault protection system, such as DEHNshort, is in place.

This modular system can be adapted to any existing installation, and will protect people and infrastructure through the detection of arc faults with the help of current and light monitoring. Thanks to its short response time of 2-3 milliseconds, the incident energy is reduced to a minimum.

How does the DEHNshort technology function?

Detection:
The current transformers at the infeed can detect the overcurrent resulting from the arc fault and transmit this information to the relevant detection device. Sensors can then detect the light emitted by the arc fault and transmit this information to the detection device, depending on the application, fibre optic and optoelectronic sensors that are available.

Evaluation:
In the detection devices, the sensor signals are converted into digital information and then linked together. If all arc fault detection criteria are fulfilled, quenching and disconnection commands are issued. The short-circuiters are immediately activated via fibre optic cables and the shunt releases via relay contacts. LEDs indicate the current status of the system and because the detection devices are integrated in the assembly door, the system status can also be evaluated if the assembly door is closed.

Arc fault quenching:
In order to quench the arc fault as quickly as possible, the detection device activates the relevant short-circuiter. The current commutates from the arc fault to the low-impedance bolted short-circuit of the two short-circuiters and the voltage drops, thus quenching the arc fault. Power thyristors ensure short commutation times that cannot be achieved by previous solutions.

Disconnection:
At the same time as the short-circuiters, the detection devices transmit a trip command to the shunt releases of all incoming circuit breakers via a floating relay contact, and disconnect the part of the switchgear assembly where the arc fault has occurred.

Recommissioning:
The switchgear assembly can be recommissioned after the fault has been rectified, the short-circuiters have been replaced and the arc fault protection system has been reset.

Where can the DEHNshort arc fault protection be inserted?
Wind turbines

Arc faults in wind turbines can frequently cause fires, which occur so high up that it is impossible for firefighters to reach and extinguish them. In such instances, the wind turbine can burn out and would need to be completely replaced. The damage can cost millions and may result in the loss of power generation. Such a total loss can be avoided with the use of DEHNshort.

Chemical and petrochemical industry
In power distribution, a continuous supply is required wherever motor control centres are integrated, especially because power outages have negative consequences for critical production processes. In addition, the protection of human life is critical in the chemical and petrochemical industry. Here, the DEHNshort arc fault protection system ensures that extremely short quenching times and thermal effects are reduced to a minimum.

Data and computer centres
Constant availability is a top priority in modern computer centres to ensure customer satisfaction. Fire is one of the most prevalent threats to computer centres and is most frequently caused by electrical faults. The DEHNshort arc fault protection system considerably reduces the risk of fire.

Railway stations
If power supply is not continuously ensured at large railway stations, the sensitive railway network may collapse. This results in reduced transportation capacity and considerable delays for passengers. The DEHNshort arc fault protection system ensures smooth railway operations.

DEHNshort takes the protection of systems and people to another level and by far exceeds the requirements of the currently applicable SANS 61641 standard.

Market leader DEHN, a globally active family-owned electrotechnical company with more than 1 700 employees worldwide, offers innovative products and solutions as well as comprehensive services in the field of surge protection, lightning protection and safety equipment.

DEHN focuses on the protection of system and building technology, the transportation, telecommunication and process sector, photovoltaic systems and wind turbines. The company's continuous growth is based on more than 100 years of tradition and experience as well as highest quality standards and consistent customer and market orientation throughout the world.