Arc Detection Systems


Arc Detection System LBW21, LBW51, LBW81

The arc detection system LBW is equipped with light-sensitive sensors which immediately detect the occurrence of internal arcs.  

This means that the effective duration of the arc is considerably shortened and the gas discharge from the switch unit is appropriately reduced.

Maximum possible staff protection due to fast disconnection after max. 1 ms reduces the load on the switchgear, decreases the gas discharge and minimises injuries.

Applications in:

  • medium voltage switch gears
  • prevention of arcs in mining
  • arc flash protection in wind turbines, power stations and national power grids
  • protection against injuries

LBW21 Arc detection system


LBW 21 Functionality

Reliable, economical and easy to install arc protection system with 4 optical sensor inputs - 1 relay output

  • Compact unit – arc fault detection
  • Fast arc fault detection within 5ms
  • Easy retrofit into existing switchgears and systems
  • No configuration necessary – plug & play installation
  • Easy installed without changes to the existing layout
  • Flexible sensor configuration for any application
  • Self-supervision of sensors and protection unit

LBW81 Arc detection system


LBW 81 Functionality

The solution for large systems covering up to: 
Inputs: 28 optical sensor + 7 current + 1 voltage inputs
Outputs: 5 relay + 8 MOSFET + 4 optical outputs – all freely programmable

Very short tripping time, even <1 ms

  • Fast MOSFET-outputs with varistor surge protection
  • Fixed cycle time 0,5 ms
  • Total Fault Clearing time depends on primary side switching device



  • TCP/IP (Ethernet) communication
  • Modbus TCP/IP or IEC61850 with Goose commands
  • Fast Disturbance Recorder sample time of 2000 Hz (0,5 ms)
  • Event log included. It can also be read by a web server


Touch screen colour display with screen saver

  • Multi-languages (Unicode) with ver-satile set of fonts/languages
  • Operator-safe read-only front display 
  • All necessary information shown automatically
  • Simple control logic for the display


Wide range of time and current settings

  •  Current input: 5 A 1 A and 2 A possible


Fully optical cables and sensors

  • Safe technology does not conduct arc plasma (HV) into the relay
  • If the arc destroys the optical cable, operation is still guaranteed
  • Sensors can be installed into the HV live parts taking into account the adequate creepage distance


Adjustable light sensitivity for each light input (1-50 kLUX)

  • Easy to install and retrofit
  • Either DIN rail or door mounting
  • Removable front panel frame


Power supply 24 - 48VDC (18-72VDC) with PoE or external power supply

  •  Redundant power supply is possible with PoE


Programming with MS Excel matrix

  • Microsoft Excel file => No need for separate configuration programs
  • No special training required
  • All features are visible and printable
  • Free user programmable names for messages events, alarms etc.


Includes optional multi-functional protection relay features.

The effects of arcs und how to plan the arc detection system LBW

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