KEY CONSIDERATIONS FOR SELECTING AN ARC-FLASH RELAY WHITE PAPER

KEY CONSIDERATIONS FOR SELECTING AN ARC-FLASH RELAY WHAT TO LOOK FOR IN AN ARC-FLASH RELAY to 50 milliseconds later1. Because an arc flash can draw a fraction of bolted-fault current, especially in its initial stages, circuit breakers alone should not be relied upon to distinguish between the arcing current and a typical inrush current. This white paper informs specifying engineers, original equipment manufacturers, designers, and end users about the most important features in arc-flash relay technology so that they can select the best relay for their application. With an arc-flash relay, there...

KEY CONSIDERATIONS FOR SELECTING AN ARC-FLASH RELAY REACTION TIME After an arc-flash relay’s input time delay, it takes a certain amount of time for its electronic output to turn on. This is a function of the type of output relay used. Solid-state outputs (such as, insulated gate bipolar transistors (IGBTs) are much faster than electromechanical relays and can operate within 200 microseconds. The arcing current during the initial stage of an arc flash is too low to trip circuit breakers. This is because circuit breakers are sized to only tolerate temporary rises in currents that are caused by...

KEY CONSIDERATIONS FOR SELECTING AN ARC-FLASH RELAY HEALTH MONITORING If the sensor has detected a fault, then the blinking light will turn solid. This allows the user to quickly and efficiently identify where the fault is located. People often say, “A chain is only as good as its weakest link.” Health monitoring ensures that the system is in good operating condition. From the sensors to the output of the arc-flash relay trip circuitry, the relay should monitor every applicable component within the system. EASE OF INSTALLATION The easiest-to-install arc-flash relays do not need PC configuration....

Small electrical panels should only use arc-flash relays that are easy to install. Beyond feeder switchgear cabinets, arc-flash protection can be extended to transformers, power converters, and motor control centers. SOFTWARE A few arc-flash relays, including the PGR-8800 and the AF05000, have software with an event logging feature. This is useful for tracking trends in the system's performance. It should record the specific sensor that started the fault, which will make troubleshooting easier. Both the PGR-8800 and AF0500 relays can log up to 1000 events, and the PGR-8800 also includes waveform...

KEY CONSIDERATIONS FOR SELECTING AN ARC-FLASH RELAY downstream motor control centers (MCCs). It is common to work on live MCCs, which drastically increases the chance of an arc-flash incident. However, the MCC may not have a main circuit breaker with a shunt trip, which would otherwise allow it to be tripped remotely. That means there is no method to remove power if an arc-flash event is detected. An arc-flash relay installed in the MCC and tell the upstream relay or a networked relay to trip the main circuit breaker feeding the MCC. Point Light Sensor The AF0500 and the PGR-8800 relays have...

KEY CONSIDERATIONS FOR SELECTING AN ARC-FLASH RELAY BUILD A CUSTOMIZED ARC-FLASH SYSTEM WITHOUT COMPLEX PROGRAMMING OR CONFIGURATION RELATED ARC-FLASH RELAY INFORMATION Connect the AF0100 and AF0500 together to design a rightsized protection system. Use the innovative digital input and output terminals to add sensors or zones. Access information about the arc-flash relays referenced in this paper. AF0100 SYSTEM 2 zones 4 sensors per zone 1 relays per zone AF0100 Adds 2 sensors and outputs to Zone 1 Application Guide Product Page Datasheet PGR-8800 AF0100 Adds 2 sensors and outputs to Zone 2 Application...

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