Arc protection

Arc protection

Arc fault protection is a technique employed for the fast clearance of arcing faults on busbars and within metal clad switchgear and associated cable boxes. The arc is detected using an optical sensor & the signal input to a protection device which also monitors the load current on the system. Conventional current based protection techniques are at times challenged by the nature of arcing faults, and can result in slow protection clearance times. Slow protection clearance times increase the risk to nearby personnel and increase the degree of damage to plant and equipment. By employing an optical detection technique, arc fault protection results in fast clearance of arcing faults.

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SIPROTEC and Reyrolle arc protection solutions

SIPROTEC 5 arc protection

Optical arc detection for SIPROTEC 5

Electric arcs are among the most dreaded fault scenarios in power supply engineering. They can be caused by a multitude of factors, such as aging of the insulation, environmental conditions as well as operating errors. Electric arcs can cause heavy damage to switchgear and present a serious hazard to operating personnel. The SIPROTEC 5 arc protection detects electric arcs through an optical sensor. Arcs are detected reliably and quickly as they develop, and the protective device can trip immediately and without delay times.

Arc protection offers:

  • Immediate detection of arcs in air-insulated compartments of switchgears by optical sensors

  • Instantaneous trip in arc fault situations limits damage to switchgear

  • The arc protection system is suited for use at all voltage Levels

Exchangeable plug-in modules

Detection of arcs is either purely optical, or optionally using an additional current criterion to avoid overfunctioning.

The arc protection module is part of the new SIPROTEC 5 series of modular, flexible and intelligent bay devices and can be used in the following device types:


Ordering versions

Additional sensor lengths can be found in our price list.
Order number
Arc protection module


Point sensor 3 m
Point sensor 35 m
Line sensor 5 m


Line sensor 40 m


Supply line for line sensor 3 m


Supply line for line sensor 10 m


Within an air insulated switchgear the sensors are placed in such a way that arcs in the busbar compartment, the circuit breaker compartment and the cable connection department are reliably detected. 


Up to 3 optical point or line sensors can be connected per plug-in module, which means a total of up to 15 sensors on modular SIPROTEC 5 devices. Point sensors are available with connecting cable lengths between 3 m and 35 m. Line sensors detect arcs along the whole sensor length. They are available from 5 m to 40 m. Line sensors are connected through a supply line to the arc protection module. The supply lines are available from 3 m to 10 m.

NXAIR switchgear unit

Detection of arcs is either purely optical, or optionally using an additional current criterion to avoid overfunctioning.

  • Reliable arc detection

  • Extremely fast tripping time

  • Minimization of thermal damage

  • Higher personal safety

  • Minimization of downtimes

  • EMI safety thanks to purely optical sensors

  • Quick and easy retrofitting



Arc protection Reyrolle 7XG31

The ReyArc range of protection devices provide multiple arc fault protection schemes depending on your protection system requirements.