Arc fault detection is critical to protecting all types of switchgear, ranging from LV,MV,& HV equipment. When arc faults occur a flash of light is emitted. This includes all IR and visible radiation spectra, Light reaches each point around the fault instantaneously. To take advantage of light’s speed, Light Arc Detectors (LAD’s) use optical electronic receivers whose technology allows a very fast response time. Standard detectors can respond within 5-10 milliseconds, ultrafast models can respond in <1 millisecond, typically 30 micro- seconds! With such fast reaction times and high accuracy levels, the devices are commonly used for critical applications, such as HV generation plants.
LAD’s are also commonly used on LV & MV metal clad switchgear, commonly found in control rooms/houses, or anytime pressure arc detection is not adequate. HV applications include, various types of switches, (gas/SF6) circuit breakers & GIS. A gas-tight connection is available for easy sensor installation onto the tank of gas/SF6 filled equipment. Selecting the correct type of arc detection is important. When monitoring compartments that are not completely dark, use a low sensitivity IR LAD. In a sealed or completely dark environment, high sensitivity is best.
Optical sensors cannot differentiate light emitted by an arc fault or operating arc. To prevent false tripping, configure the trip coil to operate when light and over current sensors signal to do so simultaneously.