In power system there are various types for groundings.

1. GROUNDING
SYSTEMS
By
Siddhesh S. Sawant

2. The objective of a grounding systemare:
1. To assure correct operation.
2. To provide safety.
3. To prevent damage.
4. To dissipate lightning strokes.
5. To stabilize voltage.
6. To divert stray RF energy.

3. 1.WHAT IS NEUTRAL WIRE?
NEUTRAL IS RETURN PATH FOR AN AC CIRCUIT
WHICH IS SUPPOSED TO CARRY CURRENT IN
NORMAL CONDITION
2.NEUTRAL WIRE IS ALWAYS ASSUMED TO BE
CHARGED (IN ACTIVE CIRCUIT). THIS NEUTRAL
WIRE IS GIVEN TO GROUND (BY GROUNDING)
TO MAKE THE SECOND TERMINAL OF NEUTRAL
WIRE AT ZERO POTENTIAL.
NEUTRAL WIRE

4. 1. WHAT IS GROUNDWIRE?
EARTHORGROUND IS FOR SAFETY CONCERNS AGAINST LEAKAGE
OR RESIDUAL CURRENTS ON THE SYSTEM VIA LEAST RESISTANCE
PATH.
2. CURRENT FLOWING THROUGHGROUNDWIRE
THIS CURRENT IS NOT DIRECTLY COMING FROM LIVE OR PHASE
WIRE, BUT IS FROM SECONDARY LINKS WHICH WAS NOT IN TOUCH
WITH LIVE SYSTEM IN NORMAL CONDITION.
3. DIFFERENCE BETWEEN APPLICATION OF GROUNDAND
EARTHWIRE
IF BOTH WILL BE MIXED THEN THE EARTH WIRE WHICH IS NOT
SUPPOSED TO CARRY ANY CURRENT IN NORMAL CONDITION , MAY
HAVE SOME CHARGES ACROSS AND WILL BECOME HAZARDOUS.
GROUND AND EARTH WIRE

5. A safe grounding design has two
objectives:
1. To provide means to carry electric currents into the earth
under normal and fault conditions without exceeding
any operating and equipment limits or adversely affecting
continuity of service.
2. To assure that a person in the vicinity of grounded
facilities is not exposed to the danger of critical electric
shock.

6. WHAT ARE THE THREE MAIN TYPES
OF GROUNDING?
The three main types are:
• EQUIPMENT GROUNDING (SAFETY)
• SYSTEMGROUNDING
• LIGHTNING/SURGE GROUNDING

7. Types of Grounding Systems
Ground rod
EARTH / GROUND BASICS
Many different types available
choice depends on local
conditions and required
function
Simplest form is a single
stake
mostly used for:
Lightning protection
Stand alone structures

8. Types of Grounding Systems
Ground rod group
EARTH / GROUND BASICS
Ground rod group -typically
for lightning protection on
larger structures or
protection around potential
hotspots such as
substations.

9. Soil Characteristics
• Soil type. Soil resistivity varies widely depending on
soil type, from as low as 1 Ohmmeter for moist
loamy topsoil to almost 10,000 Ohm-meters for
surface limestone.
• Moisture content is one of the controlling factors in
earth resistance because electrical conduction in soil
is essentially electrolytic.

10. Recommended values of earth resistance
systemsystem Recommended earthRecommended earth
resistance(ohm)resistance(ohm)
Light currentLight current 0.5-10.5-1
Low voltageLow voltage 55
MediumMedium
voltagevoltage
2.52.5
High voltageHigh voltage 0.50.5

11. Substation Earthing System
•Step & Touch voltage
•Grounding grids

12. Step and touch voltages

14. Step potential
• “Step potential” is the voltage between the feet of a
person standing nearan energized grounded object.
• It is equal to the difference in voltage, given by the
voltage distribution curve, between two points at
different distances from the “electrode.”
• A person could be at riskof injury during a fault simply
by standing nearthe grounding point.

15. Touch potential
• “Touch potential” is the voltage between the energized
object and the feet of a person in contact with the object.
• It is equal to the difference in voltage between the
energized object and a point some distance away.
• The touch potential could be nearly the full voltage across
the grounded object if that object is grounded at a point
remote from the place where the person is in contact with it.

16. Resistivity Measurement
The purpose of resistivity measurements is to quantify the
effectiveness of the earth where a grounding system will be
installed.
Differing earth materials will affect the effectiveness of the
grounding system.
The capability of different earth materials to conduct current
can be quantified by the value ρE (resistivity in Ω.m).
Resistivity measurements should be made prior to installing a
grounding system, the values measured will have an effect on
the design of the grounding system.
GROUND TESTING METHODS.

17. METHODS OF DECREASING GROUND
RESISTANCE
• Decreasing the ground resistance of a grounding system in
high resistivity soil is often a formidable task.
• Recently, some new methods have been proposed to
decrease ground resistance.
• Methods of Decreasing Ground Resistance:
1. Fall of Potential or 3 Point Method
2. Wenner’s Method or 4 Point Method

18. Soil Treatment Alternatives
• Ground enhancement material -Cement-like
compound
• Non-corrosive
• Extremely conductive
• Installed around the electrode
• Easy installation
• Permanent

19. DISADVANTAGES :
The two important disadvantages are:
• Cost.
• Possible safety hazard.

20. CONCLUSION
• Grounding And Earthing Systems form the first line of
defense in every type of Electrical Systems
• The System may be a Generator/Transformer/Housing
Installation/Generating Station/Etc.
• So it is Strictly Adviced to know the Basic Concepts of
Grounding as far as Electrical Engg. is concerned.

21. THANK
YOU!