AF0500 Series – Arc-Flash Relay Series - Littelfuse AF0500 Arc-Flash Relays Offer Superior Arc-Flash Detection

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Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. "Littelfuse" includes Littelfuse, Inc., and all of its affiliate entities.

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.

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.


  • 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

Access specifications, certifications, check availability and order parts below

Catalog #Supply
Relay Contacts ConfigOutput OptionsRelay
DimensionsWeight (lbs/g)Auto Manual ResetDigital InputsSystem typeTest ButtonSamplesCompare
AF0500-00100 / 2403 Form C (N.O./N.C.); 1 Form A (N.O.)2 IGBT switchesFail-safe / Non Fail-safe5.1 H x 7.9 W x 2.1 D in.0.7 KgLatching4Solidly Grounded AC; Resistance Grounded AC; Ungrounded ACFront-panel switch; Two remote contactsOrder
AF0500-00-CC110 / 2503 Form C (N.O./N.C.); 1 Form A (N.O.)2 IGBT switchesFail-safe / Non Fail-safe5.1 H x 7.9 W x 2.1 D in.0.7 KgLatching4Solidly Grounded AC; Resistance Grounded AC; Ungrounded ACFront-panel switch; Two remote contactsOrder

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