AF0025 Series - Arc-Flash Monitoring

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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 AF0025 series arc-flash relay is a cost-effective and OEM-focused solution that provides innovative arc-flash protection in a compact package. The relay significantly reduces arc-fault damage in ac and dc compartments by detecting the light from an arc flash using one or two optical sensors, and rapidly providing a trip signal. The compact design means it can be surface or DIN-rail mounted into the smallest spaces possible, making it an ideal OEM solution for tight cabinets such as combiner boxes and inverters. The AF0025 is conformal coated to provide protection from environmental concerns.

The use of one or two sensors makes it flexible for small or medium-size panels, with onboard or remote reset capability. There are no settings required, making it quick and easy to install without the need for a computer. The unit also includes a solid-state redundant trip circuit, providing an internal fail-safe mechanism and a very fast arc-flash response even during power up. One isolated changeover (Form C) output contact is provided to issue the trip signal to the interrupting device, which can be set to fail-safe or non-fail-safe operating modes. A second Form C contact is provided to signal an error condition such as a loss of communication to a sensor.


  • Compact solution
  • Two sensor inputs
  • Fixed light sensitivity
  • Internal fail-safe design
  • Selectable fail-safe and non-fail-safe operation
  • Error output


  • Our most compact arc-flash device, only 1.82” (46.23 mm) depth, for mounting into crowded cabinets
  • Increases protection and design flexibility
  • Flexible installation for 1 or 2 sensor applications
  • Unit requires no adjustments during installations
  • Redundant solid-state circuitry
  • Trip output can be configured to work with shunt-trip or undervoltage-trip devices
  • Fail-safe output confirms if arc-flash relay is experiencing an error or is actively providing protection


  • Solar combiner boxes
  • Inverters
  • Industrial UPS
  • Junction boxes
  • OEM panels with little available space

Access specifications, certifications, check availability and order parts below

Catalog #Supply
Relay Contacts ConfigRelay
Voltage (V)
Weight (lbs/g)Conformally coatedDigital InputsMountingSense Resistance (Ohms)Samples
AF0025-00242 Form C, 240V ac / 30 V dc, 6A resistiveFail-safe / Non Fail-safe24 V dc0.3 KgYes0Surface, or DIN Rail3 klux fixedOrder
To request product environmental information, please complete the Product Environmental Information Request Form.