Grounding in Power System Presentation
The presentation discusses the importance of grounding in power systems for safety, equipment protection, and building protection from lightning strikes. It covers types of grounding including solid grounding, resistance grounding, reactance grounding, and resonant grounding. Measurement instruments and calculation procedures for proper grounding are also reviewed. Lack of proper grounding can cause electric shocks, fires, and equipment damage. IEEE standards provide guidelines for industrial and commercial grounding systems.
3. • What is Grounding?
• Importance of Grounding
• Types of Grounding
• Applications of Grounding in
power system
• Instruments employed in
Grounding
• Grounding procedure &
calculations
• Hazards due to lack of
Grounding
• Good Grounding practice
• IEEE rules regarding Grounding
• Conclusion
4. A safety measure to prevent people from shocked.
In scientific terms ,It is a process which involves transferring of short
circuited or any leakage currents in to ground during abnormal conditions.
It provides low resistance path to divert the currents into the ground.
It is commonly termed as “Earthing”.
Electrical earthing is carried out by connecting the neutral part of the supply
system to the ground.
Low resistance conductor is best employed in the process of Grounding.
5. • A properly grounded device doesn’t leak out any
current.This prevents humans from getting shocked
during fault conditions.
Human safety
• Earthing provides stability to electronic equipment.
This helps in preventing damage to the equipment
against over currents and avoids replacement costs.
Safety of Electrical
Equipment
• Earthing device like ,lightning arrestors, which are
placed at the highest point of the building and
connected to the ground via conducting wire or
plate and this prevents damage to structure.
Protection of
Buildings and
Towers from
lightning
3 Reasons for employing Grounding:
9. • It means that there is no impedance placed intentionally
between the neutral and ground.
• Neutral of the electrical system is directly connected to
ground.
• This system of Grounding is used for voltages up to
33 kV with total power capacity not exceeding 5000 kVA
Solid Grounding means the Neutral of
electrical system is directly connected to the ground and
there is no addition impedance in the circuit.
11. Advantages Disadvantages
• Neutral is effectively held at earth
potential.
• Heavy Earth Fault currents may
interfere neighboring communication
circuits.
• Permits easy operation of earth fault
relay .
• Difficult to operate circuit breaker due
to heavy earth fault currents.
• No arcing Ground. • Not economical beyond a voltage of
33kv
• Easy to setup .
• Installation cost is economical .
12. Usually employed where the circuit impedance is high
,to keep the earth fault current within safe limits.
Used for voltages up to 33 kV with total power
capacity not exceeding 5000 kVA.
13. Resistance Grounding is when an electrical power system
has a connection between neutral line and the ground through resistor.
Here, resistor is used to limit the fault current through a neutral line.
• A high resistance conductor is used to
provide the connection between
neutral and ground.
High resistance
Grounding
• A low resistance conductor is used to
• provide the connection between
neutral and ground.
Low resistance
Grounding
14. Fig:- Material used for low
resistance Grounding
Fig:- High resistance Grounding
Fig:- Structure of Low
resistance material
15. Advantages Disadvantages
• Minimizes hazards of arcing Grounds. • Costlier than the solid grounded
system.
• Less interference to the neighboring
communication circuits.
• Enormous energy loss due to power
dissipation in Grounding resistor.
• Power dissipation in the resistor may
improve the system stability.
• Equipment needs to be highly
insulated for higher voltages.
16. It is used on a system operating at
voltages between 2.2 kV and 33 kV
with power source capacity more
than 5000 kVA.
17. Reactance Grounding is when an
electrical system has a connection between neutral and
the ground through reactor. Here, reactor is used to limit
the fault current through a neutral line.
• Fault current is depend on the magnitude of reactance in the
neutral line.
• It’s characteristics are similar to solid Grounding system.
• It is lies in between solid Grounding and Resonant
Grounding.
19. Advantages Disadvantages
• Arcing grounds are avoided. • Equipment may be insulated for higher
voltages.
• Satisfactory operation of ground fault
protection equipment.
• It is costlier than solid Grounding
system.
• Less interference to the neighboring
communication circuits.
• High transient voltages appear during
fault conditions.
20. Used for the neutral of circuits where high
charging currents are involved such as
transmission lines, underground cables,
synchronous motors, synchronous
capacitors etc.
21. Resonant Grounding is when an
electrical power system has a connection between
neutral line and the ground through arc suppression coil.
Here, arc suppression coil is used to limit the fault current
through a neutral line.
• The value of inductance in the arc suppression coil limits the
fault current and exactly balances the capacitive current ,
thereby it is called as “Resonant Grounding”.
• Arc suppression coil is also called as “Peterson coil” and the
Grounding has another name called “Peterson coil
Grounding”.
22. Fig:-Arc suppression coil Fig:-Resonant Grounding in
substation
Fig:-Arc suppression coil in
enclosure
23. Advantages Disadvantages
• It is completely effective in avoiding
arcing ground hazards.
• Lines are needed to transposed.
• It is having the advantages of
ungrounded system.
• The capacitance values changes
automatically due to various
operating conditions ,so there is a
need of changing inductance value
accordingly.
24. Used for the system earth
fault current exceeds 10kA.
25. Parameter Solid
Grounding
Resistance Grounding Reactance
Grounding
Resonant
GroundingLow
Resistance
High Resistance
Susceptible to transient
voltage
Good Good Best Best Better
Voltage stress Best Good Poor Good Good
Double Earth Fault No slight slight Slight yes
Earth Fault Arc Self Quench Partly self
quench
Partly self
quench
Partly self quench Self Quench
Protection against Arc
Fault Damage
Poor Good Best Good best
31. In order to setup proper Grounding ,resistance of the ground is taken
into the consideration.
Following instruments are employed in measuring the resistance of the
ground are:
33. There are 4 most commonly used methods for measuring the resistance of ground are:
• Simple way of finding ground resistance, but gives less accurate values .
2-point (Dead Earth) method
• Most reliable method of obtaining ground resistance.
3-point (fall of potential) method
• Most commonly and widely used method for finding ground resistance.
The values obtained are more accurate .
4-point method
• Quick and easiest method of finding ground resistance and also
effective method of finding resistance
Clamp on method
34. Identify soil type and
measure the resistance of the
soil.
Design initial Earth Grid.
Calculate resistance/impedance
for the designed grid
Calculate rise of potential
If the designed earth grid is perfect for
the given requirement ,then it goes to
final design otherwise it undergoes
redesigning process.
48. IEEE 142-2007 - IEEE Recommended Practice for Grounding of Industrial and
Commercial Power Systems
49. “A system without a proper safety & protection is just useless,
with proper system grounding , lives gets better, safer and the
equipment gets protected from being damaged.”
