How Do Arc-Flash Relays Work? How do Arc-Flash Relays Work?

Arc-Flash Protection Relays

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How Do Arc-Flash Relays Work?

Littelfuse Arc-Flash Relays and sensors are plug-and-play making them as easy to retrofit into existing switchgear as installing them into new equipment. No additional software required.

Littelfuse Arc-Flash Relays use light instead of current to detect an arc flash in under one millisecond. The fiber-optic light sensor detects light throughout the entire length of the fiber. The sensor is ideal to protect buss bars, multiple compartment installations like motor control centers, or areas with many obstructions little few sensors are interchangeable.

PGA-LS20/LS30

360˚ Light Detection

PGA-LS10

180˚ Light Detection

Visual LED indication for “Ready” or “Tripped” state to assist with fault location

Fiber sensors can be installed in locations up to 50 m(164 ft) away from relay

Littelfuse Arc-Flash Sensors have built in health monitoring. The visual LED indication flashes for “Ready”. The LED will be solid red to indicate a “Tripped” state. If the sensor isn’t flashing, then you know there’s a problem.

Point sensors are installed in switchgear so it has a line-of-sight to all powered connections where an arc can develop. Typically each compartment will have one or two sensors.

Fiber optic sensors detect an arc along its entire length. It is designed to be installed with the fiber along the back wall of switchboards or bus bars, covering all compartments with one sensor. It can also be installed in locations up to 50m away from the relay.

Unit Health

Trip Output #1

Trip Output #2

Digital Inputs/Outputs

2 Sensor Inputs

Control Power

24-48 Vdc

100-240 Vdc

Control Power

PC Connection

AF0100 Arc-Flash Relay

The AF0100 is a cost-effective solution that reduces arc-fault damage by detecting the light from an arc flash and rapidly tripping. Two remote light sensors can be connected to one relay and multiple AF0100 and/or AF0500 relays can be connected to monitor additional sensors, providing complete coverage for a wide range of applications. The compact, DIN-rail or surface-mountable body makes this an ideal solution for equipment manufacturers.

AF0500 Arc-Flash Relay

The AF0500 is a microprocessor-based arc-flash protection relay that limits arc-fault damage by detecting the light from an arc flash and rapidly tripping the feeder breaker. The unit is well suited for switchgear, transformer, motor controls center and power converter applications. Sensors, inputs, and connections are health 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. The AF0500 arc-flash protection relay includes an Ethernet interface and supports Modbus TCP communication.

2 Sensor Inputs

24-48 Vdc

Controls Power

100-240 Vdc

Control Power

PC Connection

Outputs

Digital Input/Outputs

Trip Coil #1

Digital Input/Outputs

Trip Coil #2

Modbus TCP Communications Port

110-240 Vdc

Control Power

110-240 Vdc or Battery

Control Power

Digital Inputs

Outputs

Trip Coil

PGA-LS10 Point Sensor Inputs PGA-LS20/PGA-LS30 Fiber-optic Sensor Inputs

CT Inputs

USB

PGR-8800 Arc-Flash Relay

The PGR-8800 is a UL and cUL Listed arc-flash relay that reliably detects developing arc-flash incidents without nuisance tripping by looking for a combination of excess light and current. 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.

Mighty Small

Arc-Flash System

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Simple Plug & Play Installation and Maintenance

The AF0500 Arc-Flash Relay provides tie breaker and zone tripping capabilities -one relay trips two separate zones.

Smaller incident energy. Smaller footprint. Smaller cost. The AF0100 delivers leading arc-flash technology at a size and price to make improved electrical safety accessible for everyone.

Connect the AF0100 and AF0500 together to design a right-sized protection system.Use the innovative digital input and output terminals to add sensors or zones. Buildyour custom protection without complex programming or configuration.

Arc-Flash Relay Line-up

Adjustable Trip level

Smaller incident energy. Smaller footprint. Smaller cost. The AF0100 delivers leading arc-flash technology at a size and price to make improved electrical safety accessible for everyone.

Mighty Small

Connect the AF0100 and AF0500 together to design a right-sized protection system. Use the innovative digital input and output terminals to add sensors or zones.

Arc-Flash System

In the Zone

The AF0500 Arc-Flash Relay provides tie breaker and zone tripping capabilities -one relay trips two separate zones. With unrestricted scalability, multiple AF0500 relayscan be connected to cover multiple zones.

Smaller incident energy. Smaller footprint. Smaller cost. The AF0100 delivers leading arc-flash technology at a size and price to make improved electrical safety accessible for everyone.

Mighty Small

Connect the AF0100 and AF0500 together to design a right-sized protection system. Use the innovative digital input and output terminals to add sensors or zones.

Arc-Flash System

In the Zone

Might Small

Arc-Flash System

In the Zone

The AF0500 Arc-Flash Relay provides tiebreaker and zone tripping capabilities -one relay trips two separate zones. With unrestricted scalability, multiple AF0500 relayscan be connected to cover multiple zones.

Connect the AF0100 and AF0500 together to design a right-sized protection system.Use the innovative digital input and output terminals to add sensors or zones.

Smaller incident energy. Smaller footprint. Smaller cost. The AF0100 delivers leading arc-flash technology at a size and price to make improved electrical safety accessible for everyone.

Application Examples

The PGR-8800 monitors each cabinet with a PGA-LS10 point sensor, providing arc-flash protection and fault location indication.

Switchgear Protection

In a main-tie-main application, arc-flash energy can come from either main.

Main-Tie-Main Protection

Generators are often the last line of defense in powering and protecting critical applications.

Generator Protection

Switchgear Protection

The PGR-8800 monitors each cabinet with a PGA-LS10 pointsensor, providing arc-flash protection and fault location indication. The entire length of the back bus bar is monitored by a PGA-LS20 or PGA-LS30 fiber-optic sensor. The PGR-8800 uses current transformers to monitor the current, and trips the local“feeder” circuit breaker only when high amounts of light and current are present. The PGR-8800 is also configured to only trip the upstream “main” breaker if the local circuit breaker fails to open.

Main-Tie-Main Protection

In a main-tie-main application, arc-flash energy can come from either main. Protection zones onthe AF0500 remove power from the faulted section of the bus by tripping that main and the tiebreaker (coupler). Relay A can directly trip both its Main and the tie breaker. Relay B trips its Main and uses a high-speed digital output to make Relay A open the Tie Breaker. In the event of an arc flash in the tie breaker cabinet, both mains must be tripped. Here, Relay A will trip its Main and use a digital output to make Relay B trip Main Breaker B.

Generator Protection

Generators are often the last line of defense in powering and protecting critical applications. The generator breaker is the last line of defense protecting the generator itself: there is no protection at all between the line side of the breaker and the generator. The AF0100 includes two Form-C Trip outputs that quickly respond to an arc flash, turning off the generator using the AVR or other control circuits and disconnecting from the utility or parallel generators by tripping the generator breaker. The AF0100 can be supplied directly off a battery bank and withstand the challenging environment, vibration, and space requirements of a generator application.

The PGR-8800 monitors each cabinet with a PGA-LS10 point sensor, providing arc-flash protection and fault location indication.

Switchgear Protection

Main-Tie-Main Protection

In a main-tie-main application, arc-flash energy can come from either main.

Generators are often the last line of defense in powering and protecting critical applications.

Generator Protection

Don't Rely on PPE Alone to Protect Workers!

The Littelfuse Award-winning Arc-Flash Relays help you improve safety and reduce equipment downtime in the event of an arc flash. Their simple plug-and-play installation make them the perfect, cost-effective solution.

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2 Sensor Inputs

The AF0100 includes two Form-C Trip outputs that quickly respond to an arc flash, turning off the generator using the AVR or other control circuits and disconnecting from the utility or parallel generators by tripping the generator breaker. The AF0100 can be supplied directly off a battery bank and withstand the challenging environment, vibration, and space requirements of a generator application.