Littelfuse PGR 8800 Arc Flash Relay

The Littelfuse PGR 8800 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. Phase-current-transformer inputs are provided for current-constrained, arc-flash protection and, when so equipped, a programmable definite-time overcurrent function can be enabled. An optical sensor on the PGR-8800 and an adjustable trip-level reduce the chance of nuisance tripping by setting a threshold for ambient light

The PGR-8800 accepts PGA-LS10 point sensors and PGA-LS20/PGA-LS30 fiber-optic sensors, which are designed to collect light over a wide angle and with high sensitivity. Sensors, inputs, and connections are monitored to ensure fail-safe operation. A secondary solid-state trip circuit provides a redundant trip path. A USB port is used for configuration and access to event logs and graphs. For fast fault location, front-panel and sensor LEDs indicate sensor health and which sensor(s) detected an arc fault. A maximum of four PGR-8800 units can be linked into one system.

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  • Continuous system self-supervision
  • Event logs, disturbance recording and real-time clock
  • Three-phase current, Zero-sequence current
  • Two change-over alarm contacts including IF
  • Complete digital design, simple principle;
  • Strong electrical performance;
  • Comprehensive record of fault information;
  • Double criterion of over-current and arc, high reliability;
  • Optical fiber transmits, strong electromagnetic interference resistance;
  • Programmable logic of trip exit;
  • Fast exit tripping, short total fault clearing time.



  • Reduce the harm of arc light to human body;
  • Reduce damage to equipment caused by arc short-circuit faults;
  • Avoid transformer damage caused by bus failure;
  • Protect the dc system in the station;
  • Ensure the stable operation of power substations;
  • Thermal power plant electrical section switchgear;
  • Wind farm and photovoltaic station switchgear;
  • Large municipal engineering project;



Arc-flash trip time <1 ms Limits arc-flash damage and risk of injury
Multiple sensors (up to 24) A single unit can monitor six sensors. Up to four PGR-8800 units can be linked into one system
Fail-safe system Continuous monitoring of optical sensors and inputs ensures protection
Redundant trip circuit Solid-state backup arc-detection circuit adds a second layer of safety
Adjustable light sensitivity Allows for operation in bright environments and maximum sensitivity in dark environments
LED indication (on unit and each sensor) 18 LEDs provide at-a-glance status for module and I/O state
Current detection Phase-CT inputs provide overcurrent protection and prevent nuisance trips
Optical detection Point and fiber-optic sensors provide wide detection area with sensor health trip indication
Digital inputs (6) Two each: remote trip, inhibit, and reset inputs
Service mode Allows for system test without tripping
Trip coil contact Solid-state 24–300 V dc/24–300 V ac IGBT
Indication contacts Form C and status outputs
USB interface Data logging and configuration software use a USB interface with no drivers or software installation
Built-in sensor Can be used in single-sensor systems, as a seventh sensor, and for calibration
Universal power supply/battery backup 100–240 V ac, 14–48 V dc, or 110–250 V dc supply accepted. Ability to charge and run off an external, user-supplied 24 V dc battery
Data logging On-board event recorder helps with system diagnostics
Modbus Remotely view measured values, event records, and reset trips
Upstream tripping Ability to trip upstream device if the local breaker fails to clear the fault