high voltage engineering power point presentation
- 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.no Place 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