18seminar report 2015-16 Arc fault circuit interrupter

ARC FAULT CIRCUIT INTERRUPTER

Submitted by DEEPA V P EEE S5REG NO:13030462

ACKNOWLEDGEMENT

I wish to acknowledge my sincere and heartfelt thanks to Mr.ABDUL NAZAR A.A our respected principal .At this juncture, I would like to record my most sincere gratitude to the head of department Mr. P. BABU for his generous approach in arranging facilities and guidance to complete this seminar. I express my sincere thanks to Mr. ANILKUMAR G.S lecturer in electrical department for his co-ordination and guidance for preparing and presenting the seminar. I am also thankful to all teachers and non teaching staffs of department.Last out but not least wish to express my heartfelt thanks to all my friends for their support and encouragement.

Deepa V P

CONTENTS

1. Abstract 2. Introduction 3. Arc Fault Circuit Interrupter 4. AFCI clear picture 5. Differrent types of AFCI 6. AFCI protection 7. Depend of frequency trip 8. Cutler Hammer 9. Advantages 10. Disadvantages 11. Future Applications 12.Conclusion

ABSTRACT

The objective of this paper is to increase inspector-awareness of arc-fault circuit interrupters. The significance of AFCIs is discussed in the introduction, and this is followed by a description of recent changes associated with the standard, with the National Electrical Code, and with the availability and application of the technology. Here there is a general discussion of AFCI availability, followed by a detailed description of the Cutler-Hammer line of residential miniature circuit breakers that incorporate branch/feeder AFCIs and a brief description of the technology involved. The operating experience has been excellent, relative to both fire protection and immunity from unwanted tripping. It is concluded that arc-fault circuit interrupters provide a significant fire-safety improvement for dwelling unit electrical distribution systems. They are the residential electrical safety technology of the future.

INTRODUCTION

All 120-volt, single phase, 15 and 20-ampere branch circuits supplying outlets installed in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arc-fault circuit interrupter, combination-type, installed to provide protection of the branch circuit.

What is afci

AnArc Fault Circuit Interrupter(AFCI) is a type ofduplex receptacle or circuit breaker that breaks the circuit when it detects a dangerouselectrical arc, in order to prevent electricalfires. An AFCI distinguishes between a harmless arc that occurs incidental to normal operation of switches, plugs and brushed motors and an undesirable arc that can occur.

And which prevent fires by detecting a non-working (i.e., non-intended/non-useful) electrical arc and disconnect power before the arc starts a fire. An AFCI should, but does not always, distinguish between a working arc that may occur in the brushes of a vacuum cleaner, light switch, or other household devices and a non-working arc that can occur, for instance, in a lamp cord that has a broken conductor in the cord from overuse. Arc faults in a home are one of the leading causes for household fires.

AFCIs resemble a GFCI/RCD (Ground- Fault Circuit Interrupt/Residual-Current Device) in that they both have a test button, although it is important to distinguish between the two. GFCIs are designed to protect against electrical shock, while AFCIs are primarily designed to protect against arcing and/or fire.

Picture of AFCI

DIFFERENT TYPES OF AFCI

1. Branch/Feeder Arc Fault Circuit InterrupterA device intended to be installed at the origin of a branch circuit or feeder, such as at a panel board. It is intended to provide protection of the branch-circuit wiring, feeder wiring, or both, against unwanted effects of arcing.

2. Outlet Circuit Arc Fault Circuit InterrupterA device intended to be installed at a branch-circuit outlet, such as at an outlet box. It is intended to provide protection of cord-sets and power-supply cords connected to it (when provided with receptacle outlets) against the unwanted effects of arcing.

3. Combination Arc Fault Circuit InterrupterAn AFCI which complies with the requirements for both branch feeder and outlet circuit AFCIs. . It is intended to protect downstream branch-circuit wiring and cord-sets and power-supply cords.

AFCI PROTECTIONThe AFCI is intended to prevent fire from arcs. AFCI circuit breakers are designed to meet one of two standards as specified by UL 1699: "branch" type or "combination" type (note: the Canadian Electrical Code uses different terminology but similar technical requirements). Abranch type AFCI trips on 75 amperes of arcing current from the line wire to either the neutral or ground wire. A combination type adds series arcing detection to branch type performance. Combination type AFCIs trip on 5 amperes of series arcing. Advanced electronics inside an AFCI breaker detect sudden bursts of electric current in milliseconds, long before a standard circuit breaker or fuse would trip. A "combination AFCI breaker" will provide protection against1. Parallel arcing (line to neutral).2. Series arcing (a loose, broken, or otherwise high resistance segment in a single line)3. Ground arcing (from line, or neutral, to ground)4. Overload protection (for resistance loads such as heaters. inductive loads such as motors may require additional overload protection)5. Short circuit protection

ARCING.

DURING ARC..

DEPEND OF FREQUENCY

1. One time trip

Reset the AFCITest the breakerif it doesnt trip, the AFCI is defective and must be replacedIf it does trip, check contacts between the AFCI and the panelIf everything checks out, most likely a one-time arc, overload, or false trip occurredLoads relying on arcing motors can trip the breaker.Ex. Printers, vacuums, furnacesIf AFCI continues to trip due to a single load, and nothing appears to be damaged, try replacing the AFCI with one from a different manufacturer.

2. Habitual trips (over longer intervals)

Replace the AFCI with a GFCI If it trips, cause is most likely an overloadCheck the loads to ensure the breaker isnt being overloadedIf the GFCI doesnt trip, cause is most likely an arc faultCheck the wiring between the panel and the outlet for deteriorationCheck the internal wiring of the loads for deterioration

3. Immediate re-trips (within 5 seconds)Replace the AFCI with a GFCI If it trips, a ground fault has occurredIf the GFCI doesnt trip, a short circuit may have occurred.Check the wiring between the panel and outlet for deteriorationCheck for incorrect wiring

Arc Fault vs. Ground Fault

The Ground Fault Circuit Interrupter (GFCI) protects people from potentially lethal electric shock when the GFCI detects even minute, but potentially dangerous ground faults or leaks of electrical current from a circuit. A GFCI opens the circuit when the leakage to ground exceeds 6mA. And a GFCI is a good detector of phase-to-ground arcing faults, but is unable to detect series or line to neutral arcing faults. An AFCI is designed to detect series faults, line to neutral faults and line to ground faults. The AFCI does not replace the GFCI but instead complements it. Some manufacturers will combine the two in the same unit. The technology in the AFCI is quite different and is substantially more sophisticated than the GFCI.

CUTLER-HAMMERCutler Hammer AFCI is of the branch/feeder type and consequently addresses series and parallel faults in the installed wiring;Zone 1Zone 2Zone 3

The cutler hammer AFCI is of the branch/feeder type and consequently addresses series and parallel faults in the installed wiring; Zone 1 of Figure 2. This is the origin of about 35% of residential fires associated with the electrical distribution system. In addition, the branch/feeder AFCI detects parallel faults in Zone 2, which represents the appliance cords and loads beyond the outlet, and the parallel faults in Zone 3. It also responds to all arcs to ground in Zone 1, 2 and 3.

OPERATION OF CUTLER HAMMER AFCI

The load current sensor output is fed to an arc signature filter whose output is responsive to the magnitude of the arcing currents. Normal non-arc related current components are filtered out. The signal is then amplified and fed to a logic block that distinguishes between dangerous arcing events and normal circuit transients, including the waveforms associated with incandescent-lamp-burnout. In the event of a dangerous arc, the logic block provides an output that will trip the breaker. This logic block has a second input from a ground-current-sensor-amplifier. If this logic input exceeds a preset 30 milliamp trip threshold, a trip signal is provided. This AFCI is also available in combination with ground-fault-circuit protection. In this embodiment, the ground-fault sensor is set at 5 milliamps for both the AFCI and GFCI functions.

ADVANTAGES1. Combination type AFCI circuit breakers are required on all branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms etc.2. The AFCI is intended to prevent fire from arcs 3. A branch type AFCI trips on 75 amperes of arcing current from the line wire to either the neutral or ground wire. A combination type adds series arcing detection to branch type performance. Combination type AFCIs trip on 5 amperes of series arcing.4. The advanced electronicsinside an AFCI breaker detect sudden bursts of electric current inmilliseconds; long before a standardcircuit breakerorfuse would trip.5. A "combination AFCI breaker" will provide protection against parallel arcing (line to neutral), series arcing (a loose, broken, or otherwise high resistance segment in a single line), ground arcing (from line, or neutral, to ground), overload protection and short circuit protection.6. AFCI can be triggered to quickly react and de-power a circuit if dangerous arcing is detected.

DISADVANTAGES1. For instance, lightning strikes provide voltage and current profiles that resemble arc faults. This nuisance tripping reduces the overall effectiveness of AFCIs

2. AFCIs provide no specific protection against "glowing" connections, excess current, high line voltages or low line voltages. AFCI circuit breakers for use in a panel board include a standard inverse-time circuit breaker. Glowing connections occur when relatively high electric currentexists in a relatively large resistance object. Heat comes from power dissipation. This energy, when dissipated in a small junction area, can generate temperatures above 1000C (1832F) and can ignite most flammable materials.

3. Bad wiring junctions can occur in utilization equipment, cords or in-situ wiring and especially in a defective switch, socket, plug, wiring connection and even at the circuit breaker or fuse panels. Terminal screws loosened by vibration, improper tightening or other causes offer increased resistance to the current, with consequentheating and potential thermal creep, which will cause the termination to loosen further and exacerbate the heating effect. Power Fault Circuit Interrupters (PFCI) located in receptacles are designed to prevent fires caused by glowing connections in premise wiring or panels.

4. An AFCI does not detect high line voltage due to an open neutral in amultiwire branch circuit. A multiwire branch circuit has both energized wires of a 120-240Vsplit phase service. If the neutral is broken, devices connected from a 120 V leg to the neutral may experience excess voltage, up to twice normal.

5. AFCIs do not detect low line voltage. Low line voltage can causeelectro-mechanical relays to repeatedly turn off (relay opens) and on (relay closes again). If current is flowing through the load contacts it will cause arcing across the contacts when they open. The arcing can oxidize, pit and melt the contacts. This process can increase the contact resistance, superheat the relay and lead to fires. Power fault circuit interrupters are designed to prevent fires from low voltage across loads.

FUTURE APPLICATIONS

1. AFCIs will provide protection to 120-volt dwelling unit bedroom circuits. 2. The AFCI function can also be expected to extend to the higher voltages (e.g. 240 volt, 277 volt and 480 volt) associated with commercial and industrial electrical distribution systems.3. It is also noted that the aerospace industry12 is interested in AFCI technology relative to the protection of onboard electrical wiring.

CONCLUSION

Arc-fault circuit interrupters represent the application of new technology to an old problem; namely, the need to improve fire safety in residential electrical distribution systems. Standards have been developed for the requirements of these devices, and branch/feeder AFCIs are available from many manufacturers. National, Canadian and state electrical code issues are being addressed, and the field experience with branch/feeder AFCIs has been excellent. AFCIs are the technology of the future with a fundamental focus on safety.

REFERENCE

1. Courtesy of Wikipedia, the free encyclopediahttp://en.wikipedia.org/wiki/Arc-fault_circuit_interrupter2. Arc-fault Circuit Interrupters for Aerospace Applications John Brooks3. 120224afcibreakers- slide share.4. The Truth about AFCIs - Part II

Srgptc Thriprayar Department of EEE