RAJASTHAN RAJYA VIDYUT PRASARAN NIGAM LTD. (Regd. Office: Vidyut Bhavan, Janpath, Jyoti Nagar, Jaipur ) CONSTRUCTION MANUAL FOR SUB STATIONS

Transcription

1 RAJASTHAN RAJYA VIDYUT PRASARAN NIGAM LTD. (Regd. Office: Vidyut Bhavan, Janpath, Jyoti Nagar, Jaipur ) CONSTRUCTION MANUAL FOR SUB STATIONS

2 F O R E W O R D The Engineers experienced in the field of Transmission have made this effort to compile the experience gained over the past 40 years in the form of a Manual and make it available to the Engineers and Technical Supervisors of the Company. This is a step forward to disseminate knowledge so that uniform practices and procedures are followed in the construction activities in the Company. This Manual covers all the activities related to the construction of Sub Stations. I appreciate the work done by the members of the Committee in preparing and bringing out this Construction Manual for Sub Stations. I hope that the Manual will be of immense use and reference to the Engineers of the Transmission & Construction Wing. April, 2007 Jaipur Shreemat Pandey Chairman & Managing Director Rajasthan Rajya Vidyut Prasaran Nigam Ltd.

3 P R E F A C E The construction practices in the transmission wing of RVPN have been built over the past 40 years and passed on from seniors to juniors. The new generation of Engineers, skilled Technical Supervisors and Workmen has, from time to time, constantly updated the construction practices according to the latest developments in the field of Transmission Engineering. It was felt that the construction practices built over the years be compiled in the form of a Manual and made available to Engineers and Technical Supervisors engaged in the construction activities so that uniform practices and procedures are followed in the Company. A Committee of the following Engineers experienced in the field of Transmission was assigned the task of preparing the Construction Manual: Shri S. Dhawan, Chief Engineer (MM) Shri B. N. Saini, Superintending Engineer (400 KV Design) Shri Raghuvendra Singh, Executive Engineer (Prot. II) Shri Mohan Singh Ruhela, Executive Engineer (C&M 400 KV GSS), Heerapura Shri A. D. Sharma, Assistant Engineer (Civil 400 KV Design) Shri Atul Sharma, Assistant Engineer (TLPC) I appreciate the work done by the members of the Committee in preparing and bringing out this Construction Manual for Sub Stations. I am confident that the Manual will be of great help to the Engineers posted in the Transmission & Construction Wing in discharging their duties. April, 2007 Jaipur Y. K. Raizada Director (Technical) Rajasthan Rajya Vidyut Prasaran Nigam Ltd.

4 CONTENTS Section I: SITE SELECTION & SUB STATION DESIGN Selection of Land Layout Design Safety Clearances Earth Mat Design Section II: ERECTION, TESTING AND COMMISSIONING General Instructions Structures Bus Bar and Earth Wire Aluminium Pipe Bus Bar and Joints Power Transformers Circuit Breakers Isolators Current Transformers Capacitor Voltage Transformers (CVT) / Potential Transformers (PT) Lightning Arresters Post / Polycone Insulators Wave Traps Line Matching Unit (LMU) / Line Matching Distribution Unit (LMDU) Capacitor Banks Earthing Cable Laying and Wiring Battery Sets (Valve Regulated Lead Acid / VRLA) DC Panels Battery Chargers Control & Relay Panels LT Panels PLCC Carrier Sets Carrier Protection Couplers PLCC Exchange Commissioning of Sub Station Bibliography

5 SECTION I SITE SELECTION & SUB STATION DESIGN

6 CHAPTER 1 SELECTION OF LAND 1.0 SELECTION OF SITE: 1.1 Selection of site for construction of a Grid Sub Station is the first and important activity. This needs meticulous planning, fore-sight, skillful observation and handling so that the selected site is technically, environmentally, economically and socially optimal and is the best suited to the requirements. 1.2 The main points to be considered in the selection of site for construction of a Grid Sub Station are given below. 1.3 The site should be: a) As near the load centre as possible. b) As far as possible rectangular or square in shape for ease of proper orientation of bus bars and feeders. c) Far away from obstructions, to permit easy and safe approach / termination of high voltage overhead transmission lines. d) Free from master plans / layouts or future development activities to have free line corridors for the present and in future. e) Easily accessible to the public road to facilitate transport of material. f) As far as possible near a town and away from municipal dumping grounds, burial grounds, tanneries and other obnoxious areas. g) Preferably fairly leveled ground. This facilitates reduction in leveling expenditure. h) Above highest flood level (HFL) so that there is no water logging. i) Sufficiently away from areas where police and military rifle practices are held. 1.4 The site should have as far as possible good drinking water supply for the station staff. 1.5 The site of the proposed Sub Station should not be in the vicinity of an aerodrome. The distance of a Sub Station from an aerodrome should be maintained as per regulations of the aerodrome authority. Approval in writing should be obtained from the aerodrome authority in case the Sub Station is proposed to be located near an aerodrome. 2.0 REQUIREMENT OF LAND / AREA: 2.1 The site should have sufficient area to properly accommodate the Sub Station buildings, structures, equipments, etc. and should have the sufficient area for future extension of the buildings and / or switchyard.

7 6 Construction Manual for Sub Stations 2.2 The requirement of land for construction of Sub Station including staff colony is as under: S.No. Voltage Class of GSS Required Area kv 20.0 Hectare kv 6.0 Hectare kv 3.5 Hectare 2.3 While preparing proposals for acquisition of private land and allotment of Government land, the area of land for respective Grid Sub Stations shall be taken into consideration as mentioned in para 2.2 above. While selecting Government land, the requirement may be made liberally but in other cases, where payment is to be made for the land acquisition, the requirement should be restricted to the limit mentioned in para 2.2.

8 CHAPTER 2 LAYOUT DESIGN 1.0 BUS BAR SCHEMES: The commonly used bus bar schemes at Sub Stations are: a) Single bus bar. b) Main and Auxiliary bus bar. c) Double bus bar. d) Double Main and Auxiliary bus bar e) One and a half breaker scheme. 1.1 SINGLE BUS BAR ARRANGEMENT: This is the simplest switching scheme in which each circuit is provided with one circuit breaker. This arrangement offers little security against bus bar faults and no switching flexibility resulting into quite extensive outages of bus bar and frequent maintenance of bus bar isolator(s). The entire Sub Station is lost in case of a fault on the bus bar or on any bus bar isolator and also in case of maintenance of the bus bar. Another disadvantage of this switching scheme is that in case of maintenance of circuit breaker, the associated feeder has also to be shutdown Typical Single Bus Bar arrangement is shown in Annexure MAIN AND AUXILIARY BUS ARRANGEMENT: This is technically a single bus bar arrangement with an additional bus bar called Auxiliary bus energized from main bus bars through a bus coupler circuit, i.e., for n number of circuits, it employs n + 1 circuit breakers. Each circuit is connected to the main bus bar through a circuit breaker with isolators on both sides and can be connected to the auxiliary bus bar through an isolator. The additional provision of bus coupler circuit (Auxiliary bus) facilitates taking out one circuit breaker at a time for routine overhaul and maintenance without de energizing the circuit controlled by that breaker as that circuit then gets energized through bus coupler breaker As in the case of single bus arrangement, this scheme also suffers from the disadvantages that in the event of a fault on the main bus bar or the associated isolator, the entire substation is lost. This bus arrangement has been extensively used in 132 kv Sub Stations Typical Main and Auxiliary Bus Bar arrangement is shown in Annexure DOUBLE BUS BAR ARRANGEMENT: In this scheme, a double bus bar arrangement is provided. Each circuit can be connected to either one of these bus bars through respective bus bar isolator. Bus coupler breaker is also provided so that the circuits can be switched on from one bus to the other on load. This scheme suffers from the disadvantage that when any circuit breaker is taken out for maintenance, the associated feeder has to be shutdown This Bus bar arrangement was generally used in earlier 220 kv sub stations Typical Double Bus Bar arrangement is shown in Annexure DOUBLE MAIN AND AUXILIARY BUS BAR ARRANGEMENT: The limitation of double bus bar scheme can be overcome by using additional Auxiliary bus, bus coupler breaker and Auxiliary bus isolators. The feeder is transferred to the

9 8 Construction Manual for Sub Stations Auxiliary bus during maintenance of its controlling circuit breaker without affecting the other circuits This Bus bar arrangement is generally used nowadays in 220 kv sub stations Typical Double Main and Auxiliary Bus Bar arrangement is shown in Annexure ONE AND A HALF BREAKER ARRANGEMENT: In this scheme, three circuit breakers are used for controlling two circuits which are connected between two bus bars. Normally, both the bus bars are in service A fault on any one of the bus bars is cleared by opening of the associated circuit breakers connected to the faulty bus bar without affecting continuity of supply. Similarly, any circuit breaker can be taken out for maintenance without causing interruption. Load transfer is achieved through the breakers and, therefore, the operation is simple. However, protective relaying is somewhat more involved as the central (tie) breaker has to be responsive to troubles on either feeder in the correct sequence. Besides, each element of the bay has to be rated for carrying the currents of two feeders to meet the requirement of various switching operations which increases the cost. The breaker and a half scheme is best for those substations which handle large quantities of power and where the orientation of out going feeders is in opposite directions. This scheme has been used in the 400 kv substations Typical One and a Half Breaker arrangement is shown in Annexure ELECTRICAL LAYOUT DRAWING: 2.1 Typical electrical layout drawings and sectional drawings of 400 kv, 220 kv and 132 kv sub stations with different bus bar arrangements generally adopted in RVPN are shown in Annexure 6 to Annexure BILL OF MATERIAL: 3.1 Lists of material showing the particulars of the material generally required for construction of 132 kv, 220 kv and 400 kv sub stations are given at Annexure 15 to Annexure 17 respectively. 3.2 The lists of material are only typical and cover the general requirement. Any other equipment / structure / material which may be required for construction of Sub Station as per layout and other requirements and not included in the above typical lists of material are also to be added.

10 Layout Design 9 ANNEXURE 1

11 10 Construction Manual for Sub Stations ANNEXURE 2

12 Layout Design 11 ANNEXURE 3

13 12 Construction Manual for Sub Stations ANNEXURE 4

14 Layout Design 13 ANNEXURE 5

15 14 Construction Manual for Sub Stations ANNEXURE 6

16 Layout Design 15 ANNEXURE 7

17 16 Construction Manual for Sub Stations ANNEXURE 8

18 Layout Design 17 ANNEXURE 9

19 18 Construction Manual for Sub Stations ANNEXURE 10

20 Layout Design 19 ANNEXURE 11

21 20 Construction Manual for Sub Stations ANNEXURE 12

22 Layout Design 21 ANNEXURE 13

23 22 Construction Manual for Sub Stations ANNEXURE 14

24 Layout Design 23 LIST OF MATERIAL (TYPICAL) FOR CONSTRUCTION OF 132 kv GRID SUB-STATION Annexure 15 S. No. Particulars A. Structures / Beams with nuts, bolts, washers, etc. complete. 1. BT 1 type Column 2. BT 4 type Column 3. BT 6 type Column 4. BT 7 type Column 5. BB 1 type Beam 6. P type Column 7. Q type Column (with stub) 8. Q type Column (without stub) 9. R type Column (with stub) 10. GD type (10.0 Meters) Beam 11. X type Column 12. Y type Column (with stub) 13. Y type Column (without stub) 14. Z type Column (with stub) 15. GF type Beam (5.4 Meters for 33 kv) 16. BO 1 type for 132 kv Isolators 17. BO 1 (T) type for 132 kv Tandem Isolators 18. AO 5 type for LA s / CT s / Bus CVT s 19. PIS type for 132 kv PIs 20. X 15 type for 33 kv Isolators kv CT type B. Outdoor Equipment / 33 kv Power Transformer kv Isolator without Earth Blade kv Isolator with Earth Blade kv Tandem Isolator kv Circuit Breaker with structure (110 V DC) kv Current Transformer for transformer ( / 1A, 3C) kv Current Transformer for feeder ( / 1A, 3C) kv Capacitor Voltage Transformer (110/ 3, 110/ 3) kv Lightning Arrester kv Wave Trap kv Post Insulators kv Marshalling Kiosk kv Isolator without Earth Blade kv Isolator with Earth Blade kv Circuit Breaker with structure (110 V DC) kv Current Transformer for transformer ( / 1A, 5C) kv Current Transformer for feeder ( / 1A, 2C) kv Potential Transformer (110/ 3, 110/ 3, 110/ 3) kv Lightning Arrester kv Post Insulators / kv, 250 KVA Station Transformer kv Horn Gap Fuse Set kv Marshalling Kiosk (one for 2 nos. bays)

25 24 Construction Manual for Sub Stations S. No. Particulars C. Control Room Equipment kv side of Transformer Control & Relay Panel (110 V, 1A) kv Feeder Control & Relay Panel (110 V, 1A) kv Bus Coupler Control & Relay Panel (110V, 1A) kv side Control & Relay Panel for Transformer & Bus Coupler (110V, 1A) kv Feeder Control & Relay Panel for two nos. feeders (110V, 1A) Volts, 200 AH Battery Set Volts, 200 AH Battery Charger Volts D. C. Distribution Board 9. L. T. Distribution Board (110 V DC) D. Bus Bar Material 1. Single Tension Hardware for Single Zebra (Bolted type) 2. Single Tension Hardware for Panther (Bolted type) 3. Single Suspension Hardware for Single Zebra 4. Single Suspension Hardware for Panther KV Disc Insulators, 120 KN KV Disc Insulators, 45 KN 7. ACSR Zebra Conductor 8. ACSR Panther Conductor 9. T Clamps for Zebra to Zebra 10. T Clamps for Zebra to Panther 11. T Clamps for Panther to Panther 12. P. G. Clamps for Zebra to Zebra 13. P. G. Clamps for Zebra to Panther 14. P. G. Clamps for Panther to Panther 15. P. I.Clamps for Zebra 16. P. I.Clamps for Panther 17. Tension Hardware for 7 / 3.15 mm GSS Earth wire / 3.15 mm. GSS Earth wire 19. P. G. Clamps for 7 / 3.15 mm. Earth wire E. Copper Control Cables / 16 core 2.5 sq. mm / 10 core 2.5 sq. mm core 2.5 sq. mm core 4 sq. mm core 2.5 sq. mm core 2.5 sq. mm. F. LT Power Cable (Aluminium) 1. 3½ core 300 sq. mm. G. Earthing Material 1. M. S. Round 25 mm. dia. 2. M. S. Flat mm. 3. M. S. Flat 50 6 mm. H. Others / Miscellaneous 1. M. S. Channel mm. 2. Copper Earth Bond I. Fire Fighting Equipment 1. D. C. P. type. 2. CO2 type.

26 Layout Design 25 LIST OF MATERIAL (TYPICAL) FOR CONSTRUCTION OF 220 kv GRID SUB-STATION Annexure 16 S. No. Particulars A. Structures / Beams with nuts, bolts, washers, etc. complete. 1. AT 1 type Column 2. AT 3 type Column 3. AT 4 type Column 4. AT 6 type Column 5. AT 8 type Column 6. AB 1 type Beam 7. BT 1 type Column 8. BT 4 type Column 9. BT 6 type Column 10. BT 7 type Column 11. BB 1 type Beam 12. AO 1 type for 220 kv Isolators 13. AO 1 (T) type for 220 kv Tandem Isolators 14. AO 3 type for 220 kv CT s 15. AO 4 type for 220 kv CVT s 16. AO 5 type for 220 kv LA s & for 132 kv CT s, CVT s / PT s, LA s 17. BO 1 type for 132 kv Isolators 18. BO 1 (T) type for 132 kv Tandem Isolators 19. PIS type for 220 kv & 132 kv PI s B. Outdoor Equipment / 132 kv Power Transformer kv Isolator without Earth Blade kv Isolator with Earth Blade kv Isolator with Double Earth Blade kv Tandem Isolator kv Circuit Breaker with structure (220 V DC) kv Current Transformer ( / 1A, 5C) kv Capacitor Voltage Transformer (110/ 3, 110/ 3) kv Lightning Arrester kv Wave Trap kv Post Insulators kv Marshalling Kiosk kv Isolator without Earth Blade kv Isolator with Earth Blade kv Tandem Isolator kv Circuit Breaker with structure (220 V DC) kv Current Transformer ( / 1A, 4C) kv Capacitor Voltage Transformer (110/ 3, 110/ 3) kv Lightning Arrester kv Wave Trap kv Post Insulators kv Marshalling Kiosk / kv, 250 KVA Station Transformer

27 26 Construction Manual for Sub Stations S. No. Particulars C. Control Room Equipment kv side of Transformer Control & Relay Panel (220 V DC, 1A) kv Feeder Control & Relay Panel (220 V DC, 1A) kv Bus Coupler Control & Relay Panel (220 V DC, 1A) kv side of Transformer Control & Relay Panel (220 V DC, 1A) kv Feeder Control & Relay Panel (220 V DC, 1A) kv Bus Coupler Control & Relay Panel (220 V DC, 1A) Volts, 400 AH Battery Set Volts, 400 AH Battery Charger Volts D. C. Distribution Board 10. L. T. Distribution Board (220 V DC) D. Bus Bar Material 1. Single Tension Hardware for Double Zebra (Bolted type) 2. Single Tension Hardware for Single Zebra (Bolted type) 3. Single Tension Hardware for Panther (Bolted type) 4. Single Suspension Hardware for Double Zebra 5. Single Suspension Hardware for Single Zebra 6. Single Suspension Hardware for Panther kv Disc Insulators, 120 KN kv Disc Insulators, 70 KN 9. ACSR Zebra Conductor 10. ACSR Panther Conductor 11. Spacer T Clamps for Double Zebra to Zebra (ZZ Z) 12. Spacer T Clamps for Double Zebra to Panther (ZZ P) 13. T Clamps for Zebra to Zebra (Z Z) 14. T Clamps for Zebra to Panther (Z P) 15. T Clamps for Panther to Panther (P P) 16. P. G. Clamps for Zebra to Zebra (Z Z) 17. P. G. Clamps for Zebra to Panther (Z P) 18. P. G. Clamps for Panther to Panther (P P) 19. P. I.Clamps for Zebra 20. P. I.Clamps for Panther 21. Tension Hardware for 7 / 4.00 mm GSS Earth wire / 4.00 mm. GSS Earth wire 23. P. G. Clamps for 7 / 4.00 mm. Earth wire E. Copper Control Cables / 16 core 2.5 sq. mm / 10 core 2.5 sq. mm core 6 sq. mm core 2.5 sq. mm core 4 sq. mm core 2.5 sq. mm core 2.5 sq. mm. F. LT Power Cable (Aluminium) 1. 3½ core 300 sq. mm. G. Earthing Material 1. M. S. Round 28 mm. dia. 2. M. S. Flat mm. 3. M. S. Flat 50 6 mm.

28 Layout Design 27 S. No. Particulars H. Others / Miscellaneous 1. M. S. Channel mm. 2. Copper Earth Bond I. Fire Fighting Equipment 1. D. C. P. type 2. CO2 type

29 28 Construction Manual for Sub Stations LIST OF MATERIAL (TYPICAL) FOR CONSTRUCTION OF 400 kv GRID SUB-STATION Annexure 17 S. No. Particulars A. Structures / Beams with nuts, bolts, washers, etc. complete. 1. EhT 1 type Column 2. EhB 1 type Beam 3. AT 1 type Column 4. AT 3 type Column 5. AT 4 type Column 6. AT 6 type Column 7. AT 8 type Column 8. AB 1 type Beam kv Isolator Structure kv CT Structure kv CVT Structure kv LA Structure kv PI Structure (8.0 Meter Bus Height) kv PI Structure (10.0 Meter Bus Height) kv PI Structure (13.0 Meter Bus Height) kv Wave Trap Structure 17. AO 1 type for 220 kv Isolators 18. AO 1 (T) type for 220 kv Tandem Isolators 19. AO 3 type for 220 kv CT s 20. AO 4 type for 220 kv CVT s 21. AO 5 type for 220 kv LA s 22. PIS type for 220 kv PI s kv PT structure kv PI structure for PI and Horn Gap Fuse B. Outdoor Equipment / 220 kv Power Transformer kv Isolator with Earth Blade kv Isolator with Double Earth Blade kv Isolator with Double Earth Blade (Individual Pole Operated) kv Circuit Breaker with structure (220 V DC) kv Current Transformer ( / 1A, 5C) kv Capacitor Voltage Transformer (110/ 3 V, 110/ 3 V, 110/ 3V) kv Lightning Arrester kv Polycone Insulators with corona ring kv Wave Trap (Pedestal Type) kv Marshalling Kiosk kv Isolator without Earth Blade kv Isolator with Earth Blade kv Isolator with Double Earth Blade kv Tandem Isolator kv Circuit Breaker with structure (220 V DC) kv Current Transformer ( / 1A, 5C) kv Capacitor Voltage Transformer (110/ 3 V, 110/ 3V)

30 Layout Design 29 S. No. Particulars kv Lightning Arrester kv Wave Trap kv Polycone Insulators kv Marshalling Kiosk kv Potential Transformer (110/ 3 V, 110/ 3V) for tertiary winding of Transformer / kv, 630 kva Station Transformer kv Post Insulators kv Horn gap Fuse 27. Junction Box 28. WCSM 90 / 30 mm insulation for 33 kv pipe bus with tube roll C. Control Room Equipment (220 V DC, 1 Amp.) kv Control Panel for line, Tie CB and Transformer (One and a Half Breaker Scheme) kv Relay Panel for 400 kv line kv Relay Panel for 400 kv Tie CB kv Relay Panel for 400 kv side of transformer kv Bus Bar Protection Relay Panel kv Control Panel for 220 kv side of transformer kv Control Panel for 220 kv feeders kv Control Panel for 220 kv Bus Coupler kv Relay Panel for 220 kv side of transformer kv Relay Panel for 220 kv feeders kv Relay Panel for 220 kv Bus Coupler kv Bus Bar Protection Relay Panel 13. Disturbance Recorder 14. Event Logger Panel Volts, 600 AH Battery Set Volts, 600 AH Battery Charger Volts D. C. Distribution Boards 18. L. T. Distribution Boards V DC / 240 V AC Inverter (2.5 kva) 20. Master and Slave Clock System (1 No. Master and 6 Nos. Slave) 21. Air Conditioning system 22. Mulsifier Fire fighting System 23. Synchronizing Panel / Trolley D. Bus Bar Material a) 400 kv Side: 1. Double Tension Hardware for double Moose 2. Single suspension Hardware for double Moose (Dropper Type) 3. Single suspension Hardware for double Moose (Jumper Type) KN Disc Insulators (Antifog type) 5. Spacer for Double Moose (Rigid type) 6. Spacer for Double Moose (Flexible type) 7. T Clamp for Moose 8. Double Moose to mm dia. Aluminium pipe clamp (Vertical & Horizontal take off) kv Isolator clamp for Double Moose

31 30 Construction Manual for Sub Stations S. No. Particulars kv Isolator clamp for mm dia. Aluminium pipe (Expansion type) kv CT clamp for mm dia. Aluminium pipe (Expansion type) kv CB clamp for mm dia. Aluminium pipe (Expansion type) kv PI clamp for mm dia. Aluminium pipe (Expansion type) kv PI clamp for mm dia. Aluminium pipe (Rigid type) kv PI clamp for 114.2mm dia. Aluminium pipe (Sliding type) kv LA clamp for Double Moose kv CVT clamp for Double Moose kv Wave Trap clamp for Double Moose mm dia. Aluminium pipe 20. Corona End Shield for mm dia. Aluminium pipe 21. Angular Connector for mm dia. Aluminium pipe, 20 Deg. 22. Angular Connector for mm dia. Aluminium pipe, 80 Deg. 23. Angular Connector for mm dia. Aluminium pipe, 90 Deg. 24. Angular bend Coupler for mm dia. Aluminium pipe, 110 Deg. 25. Angular bend Coupler for mm dia. Aluminium pipe, 135 Deg. 26. Straight Run Coupler for mm dia. Aluminium pipe 27. Transformer clamp for 400 kv Bushing for Double Moose b) 220 kv Side: 1. Double Tension Hardware for Quadruple Zebra 2. Double Tension Hardware for Double Zebra 3. Single Tension Hardware for Zebra 4. Single Suspension Hardware for Quadruple Zebra (Jumper type) 5. Single Suspension Hardware for Double Zebra (Dropper type) 6. Single Suspension Hardware for Double Zebra (Jumper type) 7. Single Suspension Hardware for Single Zebra KN Disc Insulators (Antifog type) 9. Spacer for Quadruple Zebra 10. Spacer for Double Zebra 11. P. I.Clamps for Double Zebra 12. T Connector; Quadruple Zebra to Quadruple Zebra 13. T Connector; Quadruple Zebra to Double Zebra 14. Spacer T Clamps for Double Zebra to Zebra (ZZ Z) 15. T Clamp; Zebra to Zebra 16. P. G. Clamps for Zebra to Zebra (Z Z) 17. Transformer clamp for 220 kv Bushing for Double Zebra 18. LA Clamp for Double Zebra 19. LA Clamp for Single Zebra 20. CVT Clamp for Single Zebra 21. CT Clamp for Double Zebra 22. CT Clamp for Single Zebra 23. CB Clamp for Double Zebra 24. Isolator Clamp for Double Zebra

32 Layout Design 31 S. No. Particulars 25. ACSR Conductor ZEBRA 26. Tension Hardware for 7 / 4.00 mm GSS Earth wire / 4.00 mm. GSS Earth wire 28. P. G. Clamps for 7 / 4.00 mm. Earth wire c) 33 kv Side: 1. Transformer clamp for 52 kv Bushing for mm dia. Aluminium pipe (Expansion type) kv PT Clamp for mm dia. Aluminium pipe (Expansion type) kv PI Clamp for mm dia. Aluminium pipe (Expansion type) kv PI Clamp for mm dia. Aluminium pipe (Rigid type) E. Copper Control Cables (FRLS) / 16 core 2.5 sq. mm / 10 core 2.5 sq. mm core 6 sq. mm core 2.5 sq. mm core 4 sq. mm core 2.5 sq. mm core 2.5 sq. mm. F. LT Power Cable (Aluminium) 1. 3½ core 300 sq. mm. 2. 3½ core 95 sq. mm. G. Earthing Material 1. M. S. Round 40 mm. dia. 2. M. S. Flat mm. 3. G. I. Flat mm 4. M. S. Flat mm. 5. M. S. Flat 50 6 mm. H. Others / Miscellaneous 1. M. S. Channel mm. 2. Copper Earth Bond I. Fire Fighting Equipment 1. D. C. P. type 2. CO2 type

33 32 Construction Manual for Sub Stations

34 CHAPTER 3 SAFETY CLEARANCES 1.0 SAFETY CLEARANCES: 1.1 The various equipments and associated / required facilities have to be so arranged within the substation that specified minimum clearances are always available from the point of view of the system reliability and safety of operating personnel. These include the minimum clearances from live parts to earth, between live parts of adjacent phases and sectional clearance between live parts of adjacent circuits / bays. It must be ensured that sufficient clearance to ground is also available within the Sub Station so as to ensure safety of the personnel moving about within the switchyard. 1.2 The Table below gives the minimum values of clearances required for Sub Stations up to 765 kv: Nominal System Voltage (kv) Highest System Voltage (kv) Table for Minimum Clearance Lightning Impulse level (kvp) Switching Impulse Voltage (kvp) Minimum clearances $ (mm) Between Phase and Earth Between Phases Safety Clearances (mm) Ground Clearance* (mm) (Ph E) (Ph Ph) (Ph E) 2550 (Ph Ph) $ These values of air clearances are the minimum values dictated by electrical consideration and do not include any addition for construction tolerances, effect of short circuits, wind effects and safety of personnel, etc. * For safety of personnel moving in the switchyard with tools & plant. Notes: 1) The values in the Table above refer to an altitude not exceeding 1000 Meters and take into account the most unfavourable conditions which may result from the atmospheric pressure variation, temperature and moisture. A correction factor of 1.25 percent per 100 Meters is to be applied for increasing the air clearance for altitudes more than 1000 Meters and up to 3000 Meters. 2) Safety Clearance is the minimum clearance to be maintained in air between the live part of the equipment on one hand and earth or another piece of equipment or conductor (on which it is necessary to carry out the work) on the other.

35 34 Construction Manual for Sub Stations 1.3 As per Rule 64 (2) of the Indian Electricity Rules, 1956, the following safety working clearances shall be maintained for the bare conductors and live parts of any apparatus in any Sub Stations, excluding over head lines of HV and EHV installations: Table for Safety Working Clearance Sl. No. Nominal System Voltage (kv) Highest System Voltage (kv) Safety Working Clearance (mm) Notes: i) The above values are valid for altitudes not exceeding 1000 Meters. A correction factor of 1.25 percent per 100 Meters is to be applied for increasing the clearance for altitudes more than 1000 Meters and up to 3000 Meters. ii) The above safety working clearances are based on an insulator height of 2440 mm, which is the height of lowest point on the insulator (where it meets the earthed metals) from the ground. iii) Safety Working Clearance is the minimum clearance to be maintained in air between the live part of the equipment on one hand and earth or another piece of equipment or conductor (on which it is necessary to carry out the work) on the other.

36 CHAPTER - 4 EARTH MAT DESIGN 1.0 BASIC REQUIREMENT: 1.1 Provision of adequate earthing system in a Sub Station is extremely important for the safety of the operating personnel as well as for proper system operation and performance of the protective devices. The primary requirements of a good earthing system in a Sub Station are: a) The impedance to ground should be as low as possible but it should not exceed 1.0 (ONE) Ohm. b) The Step Potential, which is the maximum value of the potential difference possible of being shunted by a human body between two accessible points on the ground separated by the distance of one pace (which may be assumed to be one metre), should be within safe limits. c) Touch Potential, which is the maximum value of potential difference between a point on the ground and a point on an object likely to carry fault current such that the points can be touched by a person, should also be within safe limits. 1.2 To meet these requirements, an earthed system comprising of an earthing mat buried at a suitable depth below ground and supplemented with ground rods at suitable points is provided in the Sub Stations. 1.3 All the structures & equipments in the Sub Station are connected to the earthing mat so as to ensure that under fault conditions, none of these parts is at a potential higher than that of the earthing mat. 1.4 The neutral points of different voltage levels of transformers & reactors are separately earthed at two different points. Each of these earthed points should be interconnected with the station earthing mat. 2.0 MEASUREMENT OF EARTH RESISTIVITY: 2.1 Weather Conditions: The resistivity of earth varies over a wide range depending on its moisture content. It is, therefore, advisable to conduct earth resistivity tests during the dry season in order to get conservative results. 2.2 Test Procedure: Four electrodes are driven in to the earth at equal intervals s along a straight line in the chosen direction. The depth of the electrodes in the ground shall be of the order of 30 to 50 cm. The earth resistance Megger is placed on a steady and approximately level base, the link between terminals P1 and C1 is opened and the four electrodes are connected to the instrument terminals as shown in the figure. An appropriate range on the instrument, avoiding the two ends of the scale as far as possible, is then selected to obtain clear readings.

37 36 Construction Manual for Sub Stations The resistivity is calculated from the equation given below: ρ = 2 π sr where ρ = resistivity of soil in ohm metre, s = distance between two successive electrodes in metres, and R = Megger reading in ohms. 2.3 Testing Soil Uniformity It is desirable to get information about the horizontal and vertical variations in earth resistivity over the site under consideration. The horizontal and vertical variation may be detected by repeating the tests at atleast 6 (Six) different location with a number of different electrode spacings, increasing from 1 metre to 50 metres in the steps of 1, 5, 10, 15, 25 and 50 metres. A diagram showing the typical layout for earth resistivity measurement in 6 directions is enclosed These readings, along with a sketch showing the directions in which earth resistivity readings have been taken, shall be submitted to the Superintending Engineer (400 KV Design) for designing the earth mat.

38 Earth Mat Design An example of the format in which the earth resistivity readings are to be recorded is given below. Sl. No. Electrode Spacing Megger Reading in Ohms Direction M 2. 2 M 3. 5 M M M M M Direction M 2. 2 M 3. 5 M M M M M Similarly for Direction 3 to Direction 6. Earth Resistivity in Ohm metres Remarks

39 38 Construction Manual for Sub Stations

40 SECTION II ERECTION, TESTING & COMMISSIONING

41

42 CHAPTER - 1 GENERAL INSTRUCTIONS 1.0 Transportation and unloading of the sub station material and equipment at the location shall be done in a safe manner so that they are not damaged or misplaced. 2.0 All the material and equipment shall be checked as per Bill of Material (BOM). 3.0 All support insulators, circuit breaker poles, Transformer bushings and other fragile equipment shall preferably be handled carefully with cranes having suitable boom length and handling capacity. 4.0 Sling ropes, etc. should of sufficient strength to take the load of the equipment to be erected. They should be checked for breakages of strands before being used for the erection of equipments. 5.0 The slings should be of sufficient length to avoid any damage to insulator or other fragile equipments due to excessive swing, scratching by sling ropes, etc. 6.0 Mulmul cloth shall be used for cleaning the inside and outside of hollow insulators. 7.0 Erection of equipment shall be carried out as per and in the manner prescribed in the erection, testing and commissioning manual / instructions procedures of the manufacturer. 8.0 The services of the manufacturer s Engineer, wherever necessary, may be utilized for erection, testing and commissioning of sub station equipment. 9.0 Whenever the work is required to be got done at the existing GSS where the adjacent portions may be charged, effective earthing must be ensured for safety against induced voltages so that work can be carried out without any danger / hazard to the workmen Wherever it is necessary to avail shutdowns of energized circuits for carrying out any work, the Work In - Charge shall submit a requisition to the Engineer In - charge of the GSS stating the date, time and duration of the shutdown and the section / portion which is to be kept out of circuit during the shutdown The Work In Charge shall ensure that the portion of the switchyard under shutdown has been isolated and that effective earthing of the equipment / bus bar, on which work is to be carried out, has been done The Work In Charge shall ensure that the work is completed within the requisitioned time After completion of the erection work, all surplus material including bolts and nuts, templates, etc. shall be returned to the store. All unusable cut lengths of material such as conductor, earth wire, aluminium pipes, etc. shall not be treated as wastage and shall also be deposited in the store.

43 42 Construction Manual for Sub Stations

44 CHAPTER - 2 STRUCTURES 1.0 GENERAL INSTRUCTIONS: 1.1 The structure material shall be stacked member / item wise. 1.2 The following are required to be made available to the workmen for erection of sub station structures / beams and equipment structures: i) Drawings and bills of material of structures / beams / equipment structures. ii) Templates of structures. iii) T & P such as levelling instruments, tackles, spanners, jacks, winches, ropes, derrick, etc. 2.0 TYPE OF STRUCTURES: 2.1 The types of structures generally used at sub stations are given below: Sl. No. Name of Structure Type of Structure Height of Column / Height of Conductor (Meters) A. 400 kv Structures: 1. EHT1 Column with Peak 27.0 / EHB Beam 25.3 (Width) B. 220 kv Structures: 1. AT1 Column with Peak 20.0 / AT3 Column without Peak 15.0 / AT4 Column with Peak and 20.0 / 14.5 and 9.5 Beams at two levels for Bus Bar stringing 4. AT6 Column without Peak 10.0 / AT8 Column with Peak 15.0 / AB Beam 16.6 (Width) C. 132 kv Structures: 1. BT1 Column with Peak 16.0 / BT3 Column without Peak 12.0 / BT4 Column with Peak and 16.0 / 11.5 and 7.5 Beams at two levels for Bus Bar stringing 4. BT6 Column without Peak 8.0 / BT7 Column with Peak 12.0 / BB Beam 12.2 (Width) 7. P Peak Q Column 7.5 / R Extension GD Beam 10.0 (Width)

45 44 Construction Manual for Sub Stations Sl. No. Name of Structure Type of Structure Height of Column / Height of Conductor (Meters) D. 33 kv and 11 kv Structures: 1. X Peak Y Column 5.5 / Z Extension GF 5.4 Beam for 33 kv 5.4 (Width) 5. GF 4.6 Beam for 11 kv 4.6 (Width) E. Equipment Structures: 1. AO1 220 kv Isolators AO1 (T) 220 kv Tandem -- Isolators 3. AO3 220 kv CT AO4 220 kv CVT AO5 220 kv LA & 132 kv -- CT, CVT / PT, LA 6. BO1 132 kv Isolator BO1 (T) 132 kv Tandem -- Isolator 8. X kv & 11kV -- Isolators 9. X 15 (T) 33 kv & 11kV Tandem -- Isolators 10. CT Structure 33 kv & 11kV CT, PT PI Structure 220 kv, 132kV, 33 kv & 11 kv PI SETTING OF STUB / FOUNDATION BOLTS, LEVELLING AND GROUTING: 3.1 In case of structures with foundation bolts, the template, along with the foundation bolts tightened on it with nuts on both sides, shall be placed on the foundation. The length of the foundation bolts above the template shall be sufficient so that all parts of the base plate assembly of the structure, washers, nuts and lock nuts can be tightened fully and 2 3 threads are left above the lock nut. 3.2 The template is levelled & centered with reference to its location on the foundation. The foundation bolts shall thereafter be grouted ensuring that there is no displacement during the placing of the concrete and use of vibrator. 3.3 In case of structures with stubs, the template with stubs shall be placed on the foundation. In case of structures in which the lowest member is used as a stub, the assembled lower part of the structure is placed on the foundation. This is levelled & centered with reference to its location on the foundation. The stubs / lowest member shall thereafter be grouted ensuring that there is no displacement during the placing of the concrete and use of vibrator. 3.4 While levelling and centering the structure / template, the following points should be checked:

46 Structures 45 a) Level of structure / template with reference to the finished foundation level or the ground level. b) The level of the structure / template with reference to level of other similar structures. c) Distance of centre line of the structure from the center line of other structures or from a reference point. d) Centre to centre distance between structures, particularly structures which are to be connected together, for example, by a common beam. 4.0 ERECTION OF STRUCTURES: 4.1 Method of Erection: There are mainly three methods of erection of structures, which are as below: i) Ground assembly method. ii) Section method. iii) Built up method or Piecemeal method. 4.2 Ground Assembly Method: This method is used for erection of equipment structures and is the preferred method for erection of sub station structures when crane facility is available This method consists of assembling the structure on the ground and erecting it as a complete unit The complete structure is assembled in a horizontal position near its location. On sloping or uneven ground, suitable packing is provided in the lower level area before or during assembly, as required, to eliminate / minimize stress on the structure members After the assembly is complete, the structure is picked up from the ground with the help of a crane and set on its foundation. 4.3 Section Method: This method is used for large and heavy structures when crane facility is available A mobile crane is used for erecting the structures The two faces / sides of the complete structure are assembled on the ground and then erected. Alternatively, the two faces / sides of the major sections of the structure are assembled on the ground and the same are erected as units Each assembled side is then lifted clear of the ground with the crane and is lowered into position on its foundation or fitted on to stubs or foundation bolts which are already grouted. One side is held in place with props or rope guys while the other side is being erected. The two opposite sides are then connected together with cross members In case where the major sections of the structure have been assembled, the first face of the second section is erected. After the two opposite faces have been erected, the bracings on the other two sides are bolted up. The last lift raises the top of the structure. After the structure top is erected and all side bracings have been bolted up, all the guys are thrown off. 4.4 Built up method or Piecemeal method: This method is used for large and heavy structures when crane facility is not available This method consists of erecting the structure member by member. The structure members are kept on ground serially according to erection sequence so that they can be sent up conveniently.

47 46 Construction Manual for Sub Stations The erection progresses from the bottom upwards. The four main corner leg members of the first section of the structure are first erected The cross bracings of the first section are raised one by one and bolted to the already erected corner leg angles. If these have been assembled on the ground, then they are lifted up as a unit For assembling the second section of the structure, a derrick is placed on one of the corner legs. This derrick is used for raising parts of second section. The leg members and bracings of this section are then hoisted and assembled The derrick is then shifted to the corner leg members on the top of second section to raise the parts of third section of the structure in position for assembly. The derrick is thus moved up as the structure grows. This process is continued till the complete structure is erected. 5.0 ERECTION OF BEAMS: 5.1 The two faces of the beam are assembled on the ground. 5.2 Each face of the beam is raised with the help of crane or using derricks which are placed on the top of the already erected structures on both the sides of the beam. Single or multi way pulleys with polypropylene / steel ropes are used as per load requirement. The ends of the beam are connected to the column as per fixing arrangement provided on the columns. 5.3 The bracings of the upper and lower faces of the beam are then raised up and fitted. 6.0 The columns shall be truly vertical and the beams truly horizontal after erection. Measures taken to bring the column to verticality and beam to horizontality should not result in strain on the structure members so as to cause distortion / bending of the members. 7.0 The work of erection of beams on erected columns and erection of equipment on erected structures shall not be taken up until these have been checked for tightening of the bolts & nuts. 8.0 All bolted connections shall be well tightened using spring washers & then punched at three points on the circumference of the bolt.

48 CHAPTER - 3 BUS BAR & EARTH WIRE 1.0 GENERAL INSTRUCTIONS: 1.1 Care shall be taken during sagging operations so that no damage or deformation is caused to the structures. 1.2 The ends of the cut piece of conductor / earth wire shall be tied with at least two rounds of binding wire so that the strands do not open out. The tying of the binding wire shall be done such that the binding wire does not get tightened in the groove of the T Clamps or the PG (Parallel Groove) Clamps or the terminal connectors of the equipment. 1.3 Cut lengths of conductor and earth wire which are available as surplus / left over material from line works should preferably be used for stringing of bus bars & earth wire. Cut lengths of conductor and earth wire left after stringing of bus bars and earth wire can be used for jumpering work. 2.0 BUS BAR MATERIAL: 2.1 The bus bar material generally used in 400 kv, 220 kv & 132 kv substations is given below: Sl. No. Description Bus Bar and Jumper Material kv Main Bus mm dia. Aluminium pipe kv equipment interconnection mm dia. Aluminium pipe kv overhead bus & droppers in all bays. Twin ACSR Moose kv Main Bus Quadruple / Twin ACSR Zebra / Twin AAC Tarantulla kv Auxiliary Bus ACSR Zebra kv equipment interconnection Twin ACSR Zebra / Single ACSR Zebra kv overhead bus & droppers in all Twin ACSR Zebra / Single ACSR Zebra bays kv Main Bus ACSR Zebra kv Auxiliary Bus ACSR Panther kv equipment interconnection ACSR Zebra / ACSR Panther kv overhead bus & droppers in all bays. ACSR Panther kv Main Bus ACSR Zebra kv Auxiliary Bus ACSR Zebra kv equipment interconnection, overhead bus and droppers: (i) Bus coupler & transformer bay ACSR Zebra (ii) Feeder bay. ACSR Panther kv Main Bus Twin ACSR Zebra kv Auxiliary Bus ACSR Zebra kv equipment interconnection, overhead bus and droppers: (i) Transformer bay Twin ACSR Zebra / Single ACSR Zebra (ii) Bus coupler ACSR Zebra (iii) Feeder bay. ACSR Panther

49 48 Construction Manual for Sub Stations 3.0 STRINGING OF CONDUCTOR BUS BARS: 3.1 The conductor shall be handled with care to prevent scratches on it or damage to the strands of the conductor. When the conductor is to be taken from drums, small lengths can be unwound from the drum. For longer lengths, the conductor drum shall be placed on a turn table or jacked up on a suitable size of steel shaft. The conductor shall be paid out in a manner so that there are no scratches or damages caused to the conductor due to rubbing on the sides of the drum. 3.2 Disc insulators shall be cleaned and examined for any cracks / chipping, etc. Disc insulators having any hair cracks or chipping or defective glazing or any other defect shall not be used. The limits of the area of defective glazing are given by the following formulas. D F a) Single Glaze Defect = 0.5+ Sq. cm D F b) Total Glaze Defect = 1.0+ Sq. cm where, D = Diameter of the disc in cm. F = Creepage distance in cm. 3.3 The disc insulators shall be assembled on the ground to form the suspension and tension strings as given below. Suspension String Tension String System Voltage E & M Nos. Strength (kn) Nos kv (Anti fog type) kv at 400 kv GSS (Anti fog type) kv kv kv kv Sl. No. E & M Strength (kn) 3.4 After assembly of the strings, the mouth of the W clips / R clips shall be widened to prevent any inadvertent removal during service. 3.5 The suspension and tension hardware shall be assembled as per their respective drawings and the disc insulator string shall be fitted in the requisite portion of the hardware assembly. 3.6 For stringing of bus bars, the conductor shall be fixed and tightened in the clamp of the tension hardware on one side of the bus. Thereafter, the complete hardware assembly with the conductor shall be hoisted up and fixed on the beam at this end. Sagging arrangement shall be made on the other end of the bus and the conductor shall be tensioned. 3.7 Measurement of length of conductor required for the bus shall be made thereafter and the conductor shall be released so that it returns to the ground. The conductor shall be cut to the marked length after deducting the length of the tension hardware with insulators and fixed on the clamps of the tension hardware. The conductor along with tension hardware set shall then be again pulled up and connected to the beam.

50 Bus Bar & Earth Wire Equalizing of tension in the different sub conductors of the same phase and in the different phases shall be done, if required, to ensure equal sag of all the sub conductors or between phases of the bus section as well as that of adjacent or parallel sections. 3.9 The spacers shall be fitted on the twin and quadruple conductor bus bars at the spacing shown in the drawing. The spacers shall also be provided at points where jumpers are taken from the bus bar using T clamps and / or P. G. clamps. Spacers are not used at jumper points in case T Spacers are used for taking jumpers from multi conductor bus bars. 4.0 JUMPERING OF CONDUCTORS: The jumpers connecting different sections of the bus bars as well as those connecting equipment to bus bars shall be of Y type A typical diagram of Y type jumpering is given below For making Y type jumpers, the jumper conductor(s) shall be first connected to the bus bar conductor(s) using T Clamp / Spacer T Clamp which is suitable for clamping the respective conductors, i.e., bus bar conductor(s) and the jumper conductor(s). Thereafter, the bus bar conductor(s) shall be again connected with the jumper conductor(s) using properly curved & shaped Y conductor(s) and 2 nos. PG clamps as shown in the diagram above. 4.2 The jumpering between equipment shall be done with single / twin / quadruple conductors as per the terminal connectors provided on the equipment. 4.3 In case of jumpers for twin and quadruple conductors, the spacers shall also be fitted at a suitable spacing on the jumpers in order to maintain their shape. 4.4 JUMPERING OF BUS BARS: For jumpering of different sections of bus bars on the beam, the suspension hardware set along with disc insulators shall first be hoisted and fitted on the beam Conductor of approximately the length required for the jumper shall be cut and straightened so that kinks are removed. This shall be connected to the bus bar conductor on one side of the beam after taking into consideration the natural curve of the conductor.