Procedure for earthing for different sites
- 1. EE504.32 1 DEPARTMENT OF TECHNICAL EDUCATION ANDHRAPRADESH Name :P.Ram Narayana Designation :HEES Branch :EEE Institute :K.D.R.G.P.T,Wanaparthy. Semester :V semester Subject :P.S-II(T&D) Sub-code :EE-504 Topic :Line StructuresforTransmission&Distribution Duration :50mts Sub-topic :Procedure of Earthing different line supports and earth resistance values. Teaching-aids :PPT,diagrams
- 2. EE504.32 2 OBJECTIVES On completion of this period, you would be able to know • Procedure of Earthing different line supports for LT, 11Kv, 33Kv lines • Maximum earth resistance values with the size of pipe or plate used for Earthing.
- 3. EE504.32 3 RECAP We have discussed in the last class about • Conductor spacing and ground clearance
- 4. EE504.32 4 PROCEDURE OF EARTHING DIFFERENT LINE SUPPORTS FOR LT, 11KV AND 33 KV LINES FOR SAFETY 1. Metal supports • Every fifth pole shall be earthed. • All supports provided with mass or block concrete foundation shall be earthed. 2. RCC poles • metal cross arms and insulator pins shall be bonded together and earthed • At every pole for HT lines • At every fifth pole for LT lines.
- 5. EE504.32 5 • Metal cross arms and insulator pins shall be bonded together and earthed at every fifth pole • when wood cross arms are used insulator pins are bonded together and earthed. 4. Special Structures •Special structures carrying transformers, switches, fuses etc should be earthed. 3. Wood Poles
- 6. EE504.32 6 5.Special Locations •Supports on either side of a road, railway, river crossing should be earthed
- 7. EE504.32 7 • Pipe Earthing is adopted in special locations • Coil Earthing (9m length) is adopted for all other locations • Galvanized steel wire(6 or 8 SWG) is used for earthing
- 8. EE504.32 8 4 4 G.I plate 1/2 width or 6 dia G.I pipe of 10 long and ½ thick. 2 dia. 10 long G.I pipe or 22 G.I plate of 3/8 thick. ½ dia. G.I pipe of 6 long Size of earth pipe or plate 1 2 5 Max. earth Resistance 66Kv and above 33 Kv Distribution Transformer Substation Capacity Maximum Earth Resistance values and the size of the pipe or plates used for Earthing TABLE.1
- 9. EE504.32 9 SUMMARY We have discussed about • Procedure of Earthing different line supports for LT, 11kv,33kv lines. • Maximum Earth resistance values with the size of pipe or plate used for earthing.
- 10. EE504.32 10 1. Earthing of metal structures, cross arms, insulator pins is done for LT lines on (a) All the poles (b) Every fifth pole (c) Alternate poles (d) None QUIZ
- 11. EE504.32 11 2. Maximum Earth resistance value of 33Kv line is (a) 15 (b) 10 (c) 20 (d) 2 QUIZ
- 12. EE504.32 12 FREQUENTLY ASKED QUESTIONS 1. State Maximum Earth resistance values for earthing of 33 Kv and 66Kv 2. Explain the procedure of earthing different line supports.