high voltage engineering power point presentation

hvdc

1. EE504.64 to 65 1
Name : G.LAKSHMI SRINIVASA RAO
Designation : Lecturer
Institute : Sir C.R.R.Polytechnic, Eluru
Semester : V- Semester
Branch : Electrical & Electronics Engg.
Subject : PS-II (T&D)
Major Topics: sub stations
Subject code : EE 504
Sub code& Title : Layouts of substations
Duration : 50 min
Teaching Aids : PPT, Photographs

DEPARTMENT OF TECHNICAL
EDUCATION ANDHRA PRADESH

2. EE504.64 to 65 2
In the last class we learned about
• Different types of bus bar arrangements
• Merits and demerits of each arrangement

RECAP

3. EE504.64 to 65 3
Upon the completion of this topic you would be able to know

• Typical layouts of different substations
• Pole mounted and plinth mounted substations.
• 33/11 KV substations
• 66/11 KV substations.
• 132/11 KV substations.

Objectives

4. EE504.64 to 65 4
Known to unknown
We know about
• What is a substation
• Classification of substation
• Equipment used in substation
• Auxiliary supply
• Bus bar arrangements
But we don’t know about substation layouts

5. EE504.64 to 65 5
Substation layouts
•Different types of substation layouts are as follows
1.Pole mounted and plinth mounted substations.
2.33/11 KV substations
3.66/11 KV substations.
4.132/11 KV substations.

6. EE504.64 to 65 6
POLE MOUNTED TRANSFORMER
SUBSTATION
•Features
•These are the smallest substations as compared to all
•No bending work is necessary hence these are very cheap .
•All the equipment used is of outdoor type

7. EE504.64 to 65 7
•When the substation is used for local distribution , the LT line starts from the same support.
•When it is used for single consumer , then connection will be given through under ground cable .

8. EE504.64 to 65 8
Fig.1

9. EE504.64 to 65 9
PLINTH MOUNTED SUBSTATION
•Features
•Layout of plinth mounted substation is similar to pole mounted
substation
•Beyond 200 KVA this type of substations are used .

10. EE504.64 to 65 10
•HT side is protected by horn gap fuse and switching is done
by an air break switch operated from the ground .
•On LT side , usually fuse gear is enclosed in a sheet metal
cubical mounted on the pole itself.

11. EE504.64 to 65 11
Fig.2

12. EE504.64 to 65 12
Structural layout of 33/11 KV substation
Fig.3

13. EE504.64 to 65 13
Layout of 66 KV substation
Fig.4

14. EE504.64 to 65 14
Layout of 220/132/33KV substation
Fig.5

15. EE504.64 to 65 15
EARTHING
•Earthing means, the direct connection of all the metal non-
current carrying parts of electrical equipment such as metallic
frame work, electrical motor body, isolators and circuit breakers
etc., to the surrounding earth.

16. EE504.64 to 65 16
PURPOSE OF EARTHING
•To avoid electric shock to human body
•To avoid risk of fire due to earth leakage current through unwanted path.
•To avoid earth leakage accidents through damp situations.

17. EE504.64 to 65 17
SUBSTATION EARTHING
The equipments in substations must be earthed are
1) lightning arrestors
2) circuit breakers
3)Power transformers
4)Isolators and switches

18. EE504.64 to 65 18
5)Fences
6)Panels
7)Supports
8)Current transformer
9)Potential transformer

19. EE504.64 to 65 19
SYSTEMS OF EARTHING
1)Earthing through a resistance.
2)Earthing through a reactance.
3)Earthing through a Peterson coil.
4)Earthing directly (or) solid grounding

20. EE504.64 to 65 20
EARTHING THROUGH A RESISTANCE
•The value of the resistance commonly used is quite high as compared
with system reactance
•With increase in operating voltage the value of resistance required for
earthing also increases

21. EE504.64 to 65 21
EARTHING THROUGH REACTANCE
•In reactance earthing system the neutral is earthed through
impedance which is highly reactive
•The value of reactance required is to keep currents within safe limits

22. EE504.64 to 65 22
EARTHING THROUGH PETERSON COIL
•In this type of earthing the value of inductive reactance is such
that the fault current balances exactly the charging current
•This is also called as resonant grounding

23. EE504.64 to 65 23
EARTHING DIRECTLY (OR) SOLID
GROUNDING
•The neutral of the system is directly earthed or short circuited.

24. EE504.64 to 65 24
EARTH RESISTANCES
•As per the rural electrification corporation rules the earth
resistance must be within the specified limits
S.noPlace Value of earth resistance
1 Power stations Less than 0.5 ohms
2 Major substations 1 ohm
3 Other substations 2 ohms
4 Distribution
transformer stations
5 ohms
5 Places at supports,
towers, over head
lines
25 ohms
TABLE NO.1

25. EE504.64 to 65 25
TYPES OF EARTHING
•Pipe earthing
•Plate earthing

26. EE504.64 to 65 26
PIPE EARTHING
Fig.6

27. EE504.64 to 65 27
•For power stations and major substations:
•cast iron pipes 15 cm in diameter , 3 mts long and not less
than 1.25 cms thick .

28. EE504.64 to 65 28
2.For small substations:

•Galvanized Pipes 5 Cms in diameter and 3 mts long

29. EE504.64 to 65 29
PLATE EARTHING
Fig.7

30. EE504.64 to 65 30
1.For large power stations and major substations:
•1.2 mts x 1.2 mts cast iron plates of 1.25 cms thick.

31. EE504.64 to 65 31
2.Small substations :
•0.6 m x 0.6 m cast iron plates of 0.95 cms thick .

32. EE504.64 to 65 32
Earthing plane of 66/11 KV
Fig.8

33. EE504.64 to 65 33
Earthing layout of 132/33-11 KV substation
Fig.9

34. EE504.64 to 65 34
SUMMARY
We have discussed about
• Pole and plinth mounted sub stations
• 33KV ,11KV,132KV sub stations
• Substation earthing
• Systems of earthing
• Types of earthing

35. EE504.64 to 65 35
QUIZ
1.Resistance of earth system of power stations should not
exceed the limit of
a. 5 ohms
b. 2 ohms
c. 1 ohm
d. 0.5 ohm

36. EE504.64 to 65 36
2) Resistance of major substations should not exceed
a. 5 ohms
b. 2 ohms
c. 1 ohm
d. 0.5 ohm

Quiz

37. EE504.64 to 65 37
Frequently asked questions
1.Draw the earthing layout of 33/11 KV substation and label the
parts?
2.List the parts to be earthed in the substation
3.Draw a neat sketch of 11KV/400 V pole-mounted sub station
and label parts
4.Draw a single line diagram of 66/11KV sub station