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1. Introduction
Eaton Arc Flash Relay System
MN026010EN March 2016 www.eaton.com
1. Introduction
The Eaton Arc Flash Relay (EAFR) system is a combination
of arc flash relay modules and sensors designed to detect
and clear arc flash events in low and medium voltage elec-
trical assemblies.
An arc fault is the most devastating type of fault in medium
voltage (MV) and low voltage (LV) switchgear. If an arc fault
occurs, the EAFR system reduces arc energy by quickly
clearing the current feeding the arc.
The EAFR system can measure both light and current to
eliminate nuisance operation. In addition, it’s modular design
makes it an excellent candidate for both new and retrofit
installations.
2. Overview
2.1 Speed
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As fast as 2 ms operate time.
2.2 Flexibility
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Easy adaptation to any switchgear and trip scheme.
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Variety of arc sensors available.
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Long distance possible between units.
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Practically an unlimited number of units can be intercon-
nected in one system.
2.3 Reliability
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Standard copper wire for communication between units.
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Superior isolation levels for external disturbances - tested
at the highest EMC classes.
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Full internal monitoring of all system components and
interconnections.
2.4 Typical Applications
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Low voltage switchgear/switchboards
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Medium voltage switchgear
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Low/medium voltage motor control
3. Features
3.1 Protection Features
The EAFR system is a sophisticated micro-processor based
arc flash protection system with combined current and arc
sensing. Combined current and arc sensing provides an
integrated dual trip criteria. It is designed to minimize the
damage caused by an arcing fault (arc flash) by tripping the
circuit breaker sourcing the fault current.
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Three phase instantaneous overcurrent elements (50P)
(Permissive only with light input)
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Ground instantaneous overcurrent element (50G)
(Permissive only with light input)
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Breaker failure (50BF)
3.2 Current Sensing
The main units EAFR-110F and EAFR-110P each contain
four current transformer inputs that provide sensing for the
phase and ground instantaneous overcurrent elements.
These elements act as a permissive for the light sensing
inputs so that when they are incorporated into the scheme
both current and light must be present to initiate a trip com-
mand. This current information can be shared with down-
stream modules as well.
3.3 Light Sensing
Arc flash light can be collected by either point sensors or
fiber loop sensors. Up to 12 point sensors or 3 loop sen-
sors can be connected to each module. Light sensing can
initiate a breaker trip independent of current if desired.
Because point sensors are interconnected with copper wire
they can provide a much better installation for Electrical
OEM’s where the system can be fully wired and tested in
the factory. Sensor wiring allows daisy chaining up to three
sensors over a distance of 100 meters. Fiber loop sensors
are available in either plastic or glass versions. Point sen-
sors are available in multiple sensitivity levels with the 8K
lux sensor being suitable for most applications.
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Point sensors
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Up to 12 sensors per module
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Fiber loop sensors
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Up to 3 sensors per module
3.4 Relay Outputs
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Four Trip Relays per module (7 mS)
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Two High Speed outputs (2 mS – EAFR-110P, EAFR-110F)
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System failure relay
