This document discusses electrical faults in domestic buildings and the devices used to protect circuits. It introduces major faults like overcurrent and earth leakage. The protection devices discussed are the earth leakage circuit breaker (ELCB) and miniature circuit breaker (MCB). The document then describes an experimental setup and automatic system to restore power after faults by resetting the ELCB and detecting fault locations.

1. ARSHAD A K
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S7F
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2.  INTRODUCTION
 MAJOR FAULTS
 ELCB
 MCB
 SYSTEM OPERATION
 EXPERIMENTAL SETUP
 CONCLUSION
 REFERENCE
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3.  Power reliability and continuity is very important and critical
to a domestic building..
 Single-phase is very common system used in domestic..
 Three common factors are faulty wiring in the house, improper
flexible cords, and faulty appliance..
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4. FAULTS
OVERCURRENT
FAULT
OVERLOAD SHORTCIRCUIT
EARTHLEAKAGE
FAULT
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5.  Overcurrent fault is occur when the current exceeds the rated
current carrying capacity of the conductor
 There are two types:
 Short circuit
 Over load
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6.  It exists when unintended path is established between the
normal current carrying conductors which has contact directly
or indirectly with earth.
 Earth leakage is residual current typically in very low current
range.
 If it increases a threshold for that device or circuit it becomes
earth fault which is essentially a short between phase and earth
or body
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7.  There are two types of ELCB: voltage operated and current
operated..
 The RCD operates by measuring the current balance between
two conductors using a differential current transformer..
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9.  The MCB is resettable protective device which designed to
isolate a circuit during an overcurrent (both overload and short
circuit) event without using fuse.
 MCB is choosing for building protection rather than fuse
because of its resettable capability.
 The mechanism of operation includes a movable handle that
extends at the outside of the housing..
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10.  The handle has basically three stable positions: on, off, and
tripped.
 The mechanism will respond to instantaneous high current to
open the contact and therefore interrupt the current flow.
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11.  The automatic system is designed for domestic electrical
system to auto-reset ELCB and auto-detection if any
permanent fault occurred.
 The system operation is divided into two parts:
 Power recovery
 Fault location detection.
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12.  Power recovery is a process of turning back the power ON
when electric power encounters unexpected shut down for a
period of time due to tripping or faults..
 Currently, for home electrical system, power recovery is
manually done..
 Once fault detected and isolated, ELCB will be switched ON
and supply is restored.
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13.  Domestic electrical fault would normally occur at individual
circuit, either switches or sockets.
 Fault location detection may facilitate the process of power
recovery to recover from unexpected power outage.
 Fault detection can be done through current difference
between the amount of current travelling into the load and the
current travelling out of the load.
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15.  Current Sensor
It is very important to select an accurate current sensor
in this project.
 The accuracy of current value measured by this current sensor
will lead to the accurateness of detecting fault location and
fault isolation from the main line.
 Arduino UNO Board
The Arduino UNO board is the main microcontroller board in
this project.
 All calculations and data collections will be done through this
board.
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16.  A circuit has been setup as in Fig. 3 with two current sensors
(line and neutral) connected to the input of Arduino board for
simulation purpose.
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17.  This test is to verify that the system is able to detect normal
condition, at which power is ON.
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18.  This section is to test
the functionality of
automatic ELCB reset
operation.
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19.  Once the ELCB reset operation reaches “Reset Test: 3”, and
the power is still “0”, the system will check each MCB since
MCB is installed at individual circuit.
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21.  Automated Electrical Protection System or Auto-EProS can be
considered as a new invention in electrical protection field.
 It is an additional feature to the electrical protection system to
enhance the performance of domestic protection system.
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22.  Stevenson, William D., Jr., “Elements of Power Systems
Analysis”,McGraw-Hill Electrical And Electronic Engineering
Series
 Electrical Safety Hazards Handbook”, Littelfuse USA, 2005
 QO and QOB Miniature Circuit Breakers with Ground Fault
Protection, Schneider Electric, 2009
 “Residual Current Device”. [Online] Retrieved from
http://en.wikipedia.org/ wiki/Residual-current device
 “Difference between Fuse and Circuit Breaker”. [Online]
Retrieved from http://www.wisegeek.com/what-is-the-
difference-between-a-fuseand- a-circuit-breaker.htm
 Miniature Circuit Breakers: Application Guide”, ABB Inc., USA,
Apr 2009
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