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The AF0500 series arc-flash relay is a microprocessor-based protection relay that limits arc-flash damage by using light sensors to rapidly detect an arc and then trip a circuit breaker. Any combination of point and fiber-optic sensors can be connected to the relay to provide maximum protection. The AF0500 accepts PGA-LS10 point sensors and PGA-LS20/PGA-LS30 fiber-optic sensors. Sensors, inputs, and connections are monitored to ensure fail-safe operation. LEDs on the relay and on the sensors indicate sensor health and which sensor(s) detected an arc fault. A secondary solid-state trip circuit provides a redundant trip path. The AF0500 relay includes an Ethernet interface and supports Modbus® TCP communication. Zone tripping, upstream breaker tripping, and tie-breaker tripping applications can be easily configured. A USB port is used for configuration and access to event logs. This series is well suited for switchgear, transformer, and power converter applications.



  • Arc-flash trip time <1 ms
  • Four arc sensor inputs
  • Two IGBT high-speed trip outputs
  • Universal power supply
  • Discrete wire networking
  • Fail-safe system
  • USB interface
  • Unit health indication
  • LED indication (on unit and each sensor)
  • Data logging
  • Ethernet interface


Sensor Placement

The AF0500 arc-flash relay and sensors are easily installed in retrofit projects and new switchgear with little or no re-configuration. Simple applications work straight out of the box with no need for PC configuration. More complex systems with multiple power sources are configured using the relay’s built-in USB interface software. Generally, it is recommended to mount one or two sensors per cubicle to cover all horizontal and vertical bus bars, breaker compartments, drawers, and anywhere that there is a risk for an arc fault. Threading a fiber-optic sensor through the cabinets and in areas where point-sensor coverage is uncertain results in complete coverage and an added level of redundancy. Even if policy is to only work on de-energized systems, all maintenance areas should be monitored to prevent potential damage and additional cost.

Littelfuse Arc Flash Relay AF0500-00

Only 2 left in stock

An arc flash is a mass of heat and pressure caused by a switchgear fault. Not only does it cause power outages, but it can also result in loss of business, extensive material damage, and can seriously jeopardize the safety of operational staff. Should a fault occur, arc flash protection minimizes burning time by quickly tripping the circuit breaker, cutting off the current feeding the arc. Short arc burning times are critical, especially when the arc develops during maintenance work on the switchgear, causing property damages. The unique arc fault functionality adds a new dimension to the total protection and reliability of the power distribution installation.


  • Low investment costs and fast installation
    The pre-designed and documented protection schemes are cost-effective, fast to install and commission, and require low investment. One successful operation of the arc protection system provides an immediate return on the investment. 
  • Reduced loss of production
    The faster that arc protection operates, the less damage is caused by the arc fault, reducing the possible outage of the power supply. 
  • Easy installation in existing switchgear
    The product’s design allows for easy installation in existing switchgear. A number of accessories simplify and speed up installation in existing switchgear and electrical panels thanks to its compact design and installation kits. 
  • Reduced insurance costs
    The faster and better the protection system, the more generous the insurance terms and lower the cost should be.   
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