This document discusses the importance of proper grounding and bonding for electrical systems. It defines key terms like grounding, bonding, and ground loops. The primary objectives of grounding are safety, fault protection, and creating a signal reference ground. Improper grounding can cause problems like earth loops, electromagnetic interference, loose connections, and reduced protection. The document outlines requirements for grounding in the National Electrical Code and describes components of effective grounding systems, including ground electrodes, conductors, and techniques like single-point and multipoint grounding. Signal reference grounds are important for sensitive equipment. Overall, the document emphasizes that proper grounding is fundamental to ensuring electrical system stability and preventing shock hazards.

1. Department of Electrical Engineering
Zakir Hussain College of Engineering & Technology
Aligarh Muslim University, Aligarh
EE-453
TOPIC :
“Effect Of Grounding On Power Quality”
HOME ASSIGNMENT

2. Definitions
Grounding: is a conducting
connection by which an electrical
circuit or equipment is connected to
earth or to some conducting body of
relatively large extent that serves in
place of earth.
Bonding: is intentional electrical
interconnecting of conductive paths
in order to ensure common
electrical potential between the
bonded parts.

3. Primary Objectives
Primary objectives of grounding and bonding:
1. Safety that covers both personal as well as equipment protection.
2. Provide a low-impedance path for the flow of fault current in case
of a ground fault so that the protective device could isolate the
faulted circuit from the power source.
3. Create a ground reference plane for sensitive electrical equipment.
This is known as the signal reference ground (SRG).

4. Shock and fire hazard

5. Problem arises due to improper grounding
• The biggest grounding issues are:
• Earth loops, noise of electromagnetic interference, loose
connections, poor earthing, lightning, neutral conductor of
insufficient capacity, loss of protection ground, redundant ground
rods, etc.
• EARTH LOOP: two sensitive devices interconnected by a signal
conductor whose earth connections can be at different potential,
originating an earth loop where some current will flow.
• If there is more than one connection to earth, several paths will exist
for the fault currents, high voltage potentials can appear inside the
installation.

6. • The loose connections generate surges for interruption of inductive
circuits (noise of high frequency) that can damage the sensitive
electronic devices.
• This loose connection can represent a high resistance path to earth,
avoiding the dissipation in earth of the energy of discharges
• Power Quality refer to the presence of noises in the communications
circuits due fundamentally to the existence of earth loops, when the
circuit has several distributed groundings.

7. SOLUTIONS OF POWER QUALITY PROBLEM
1 SEPERATION:
The sensitive and non-sensitive loads do not work very well when they are
together, therefore the separation should be made with the phase and with the
neutral conductors.
2. SELECTION:
• Choosing the conductor that is able to drive certain current of 50 or 60 Hz with an
acceptable voltage drop.
• E.g Twisted conductors, b; coaxial cables, and c; optic fiber.
3.SHIELDING:
• The electric shielding acts like a true “armor”,absorbing or reflecting the
electromagnetic or radiofrequency interferences.

8. COMPONENTS OF GROUNDING SYSTEM
• Grounded conductor: A circuit conductor that is intentionally
grounded.
• Grounding conductor: A conductor used to connect the grounded
circuit of a system to a grounding electrode.
• Equipment grounding conductor: Conductor used to connect the
non-current carrying metal parts of equipment, raceways, and other
enclosures to the system grounded conductor.
• Ground: Earth or some conducting body of relatively large extent that
serves in place of the earth.

9. • Grounding electrode conductor: Conductor used to connect the
grounding electrode to the equipment grounding conductor.
• Main bonding jumper: An unspliced connection used to connect the
equipment grounding conductor and the service disconnect enclosure
to the grounded conductor of a power system.
• Ground electrode: A conductor or body of conductors in intimate
contact with the earth for the purpose of providing a connection with
the ground.

10. NATIONAL ELECTRICAL COD (NEC)
GROUNDING REQUIREMENTS
• Grounding of electrical systems is mandated by the electrical codes
that govern the operation of electrical power systems.
• Article 250 of the NEC requires that the following electrical systems of
50 to 1000 V should be grounded:
• Systems that can be grounded so that the maximum voltage to ground does
not exceed 150 V.
• Three-phase, four-wire, Wye-connected systems in which the neutral is used
as a circuit conductor.
• Three-phase, four-wire, Δ-connected systems in which the midpoint of one
phase winding is used as a circuit conductor.

12. POWER GROUND SYSTEM
• A good ground electrode grid system with low resistance to earth is a
vital foundation for the entire power system for the facility.
• When a ground fault occurs, large ground return currents are set up
which causes the overcurrent protection to open and isolate the load
from the power source.
• Article 250-95 of the NEC (1999) requires ground fault protection for
solidly grounded Wye-connected electrical services of more than 150
V to ground, not exceeding 600 V phase-to-phase, for each service
rated 1000 A or more.

14. • Very little current to cause electrical shock and even loss of life. This is
why ground fault circuit interrupters (GFCIs) are required by the NEC
for convenience outlets in certain areas of homes or facilities.
• GFCI protection is set to open a circuit at a current of 5 mA. The GFCI
is not intended for equipment protection but is strictly for personal
protection

15. SIGNAL REFERENCE GROUND
• SRG is a ground plane that provides all sensitive equipment connected
to it a reference point for smooth their smooth operation.
• Better communication between the reference points of the two circuits.
• Bonded to other building ground electrodes such as building steel,
ground ring, or concrete-encased electrodes.

17. SIGNAL REFERENCE GROUND METHODS
• The SRG can take many forms, depending on the user preference.
• single conductor installed underneath the floor and looped around
the space of the computer centre.
• installations use copper strips instead of circular conductors to form
the grid.
• sheets of copper under the floor of the computer centre as the SRG.

20. • bonded to the building steel and the stanchions that support the
raised floor of the computer Center, provides excellent noise
immunity and allows the creation of a good reference plane for the
sensitive circuits .
• The principle behind the configuration of the SRG does not change
whether the ground reference plane is below ground or above
ground.
• It is important that all noise producing loads be kept away from the
SRG.

21. SINGLE-POINT AND MULTIPOINT GROUNDING
• With multipoint grounding, every piece of individually grounded
whereas, with single-point grounding, each equipment is connected
to a common bus or reference plane, which in turn is bonded to the
building ground grid electrode.
• Multipoint grounding is adequate at power frequencies.
• convenient and economical, but it is neither effective nor
recommended for grounding sensitive devices.

22. Multipoint ground system.

23. GROUND LOOPS
• Defined as a potentially detrimental loop formed when two or more
points in an electrical system that are normally at ground potential
are connected by a conducting path such that either or both points
are not at the same potential.
• Ground loops are the result of faulty or improper facility wiring
practices that cause stray currents to flow in the ground path,
creating a voltage differential between two points in the ground
system.
• They may also be due to a high-resistance or high-impedance.
• connection between a device and the ground plane.

24. Ground loop voltage and current.

25. ELECTROCHEMICAL REACTIONS
DUE TO GROUND GRIDS
• When two dissimilar metals are installed in damp or wet soil, an
electrolytic cell is formed.
• Over the course of time, the steel members that are more
electropositive will start to disintegrate .
• Mitigation by sacrificial anodes are installed in the ground.

26. EXAMPLES OF GROUNDING ANOMALIES
OR PROBLEMS
• LOSS OF GROUND CAUSES FATALITY
high-current welders
• STRAY GROUND LOOP CURRENTS CAUSE COMPUTER DAMAGE
In a commercial building, computers were burning up at an alarming
rate
• GROUND NOISE CAUSES ADJUSTABLE SPEED DRIVES TO SHUT
DOWN
newspaper printing facility

27. CONCLUSIONS
• Reference is fundamental to the existence of stability.
• For electrical systems, reference is the ground or some other body
large enough to serve in place of the ground, and electrical stability
depends on how sound this reference is.
• Only ground cannot be a reference .
• Grounding is the foundation of any electrical power, communication,
or data-processing system; when the foundation is taken care of, the
rest of the system will be stable.

28. REFERENCES
1. J.C. Gomez, G. Zamanillo, S. Nesci, L. Sanchez.
‘‘EFFECT OF THE POWER SYSTEM GROUNDING ON POWER QUALITY’’
IEEE CONFERENCE.
2. C SANKARAN BOOK ‘‘POWER QUALITY’’ 2002 by CRC Press LLC.