E.1.12: GROUNDING SYSTEM

Transcription

1 E1-GRD-1/5 E.1.12: GROUNDING SYSTEM B.1 Technical Characteristics and Requirements B.1.1 Grounding Design Criteria a. Fault duration, sec 1 b. Total fault level (line to ground), ka 20 c. Grounding connection Exothermic d. Grid conductor 125 mm 2 tin-annealed bare copper stranded conductor e. Bonding conductor (riser) 125 mm 2 tin-annealed copper stranded conductor with 3.3kV PVC insulation f. Burial depth of grid conductor below finished grade, m 0.50 (min.) g. Equipment and structure grounding conductor connected to different grid conductors Refer to of each equipment h. Ground mat design resistance 0.5 ohms max. i. Permissible temperature rise of grid copper Conductor, o C 300 j. Ground rod 1. Type Copperweld 2. Diameter, mm Not less than Length/Section, m 3 k. Resistivity of crushed rock, (wet). ohm 3000 l. Approximate Area of substation to be covered by the ground grid Refer to Bid Drawings m. Soil resistivity (for calculation), ohmmeter By Contractor 1 B.1.2 Overhead Ground Wire a. Type 7 No. 8 AWG aluminum-clad steel wire b. Ultimate strength, not less than, kg 7,277 1 Design of grounding system is responsibility of Contractor including measurement of the actual soil resistivity.

2 E1-GRD-2/5 c. Outside diameter, mm Manufacturer s std. d. Weight of zinc coating for galvanized and aluminized steel wire if specified in item a., not less than, g/m 2 e. Weight of aluminum coating for aluminum-clad steel wire, if specified in item a., not less than, g/m f. No. of Wires 7 g. Nominal diameter of wire, mm h. Cross-sectional area, mm i. Approx. weight, kg/m k. Modulus of elasticity in kg/m 2 16,169 (final) l. Coefficient of linear expansion, x10-6 / 0 C m. Elongation in 610 mm, not less than, % By Contractor n. Resistance at 20 C, max o. Recommended length per reel, if specified, m 1,500 N/A B.1.3 B.1.4 B.1.5 B Grounding Cable for Ground Mat a. Nominal sectional area, mm mm 2 b. Construction of stranded conductor (no./dia. in mm) 19/2.68 c. Outside diameter of cable, mm 13.4 approx. d. DC Resistance at 20 0 C ohms/km e. Standard weight, kg/m f. Tin-annealed (Yes, No) Yes Bonding Conductor (Riser) a. Size, mm mm 2 b. Conductor Metal Tin Annealed Copper Stranded Wire c. Conductor shape Circular stranded d. Insulated? Yes e. Type of insulation PVC Accessories for Overhead Ground Wire Suspension Ground Wire Materials a. Type N/A b. Applied conductor(specify type of conductor used) N/A

3 E1-GRD-3/5 c. Armor rods (Specify used or not used) N/A d. Ultimate breaking strength, kg N/a e. Slip Strength, kg N/A B Tension Wire Ground Materials B Tension Clamp a. Type of Clamp Bolted b. Applied conductor (Specify type of conductor used) Aluminum-clad steel wire, 7 No. 8 AWG c. Ultimate breaking strength, kg Not less than 95% UTS of OHGW d. Slip Strength, kg 8,300 B Jumper Clamp a. Ultimate breaking strength, kg 1,500 b. Slip Strength, kg 700 c. Type Wedge Pressure Clamp B Parallel Groove Clamp a. Material Aluminum Alloy b. Type Bolted Type c. Applied conductor Aluminum clad steel wire 7/8 AWG d. Slip strength, kg Not less than 15% UTS of the applied conductor B.1.6 Cable Reel Requirements for the Ground Cable and Overhead Ground Wire a. Materials (specify wood or steel) Wood b. Returnable (Yes, No) No c. If Yes, return within no. of months after installation N/A B.2 Test and Test Report(s) Requirements B.2.1 Test Requirements a. Type test and/or design test reports required for the grounding conductor and materials to be supplied (Specify Yes or No) ** Yes ** Contractor shall place in the filled-in data submitted or will submit as appropriate.

4 E1-GRD-4/5 b. Measurement of ground grid resistance after completion of grounding system to be measured before and after connection of the external ground wires of the transmission line to the substation ground system. (Specify Yes or No) Yes B.3 Auxiliary Power Supply B.3.1 No auxiliary power supply is required.. B.4 Spare Parts B.4.1 No particular spares and spare parts are required for the grounding system. The completeness of the grounding system with measurement (step and touch potential and required ground resistance) shall be the responsibility of the Contractor before its handling-over to the Employer. B.5 Tools B.5.1 All tools, i.e. compression tools for compressing the various type of grounding connections, tools required for the installation of wedge pressure clamp, etc. necessary for completing the works for the grounding system shall be the responsibility of the Contractor before its turn over to the Employer. B.6 Other Technical Requirements for the Grounding System B.6.1 The grounding is hereby referred to Paragraph of the Technical Specification whereby resistivity measurement including step and touch potential will be carried out and designed by the Contractor. In order to minimize the effect of seasonal variations of the earth resistance and the interruption of the overhead ground wire, the grounding system shall be designed for the worst condition, i.e. the overhead ground wire connection shall not be considered including that of the existing overhead ground wire connection. All works, labor and materials necessary for the complete, safety and efficient grounding system for the substations shall be included in the pay item for Grounding Materials for the Substation in the Bid Price Schedules for the substation. C. Other Technical Data to be Filled-in by Contractor C.1 The Contractor furnished data and information are included in this Specification to indicate the guaranteed performance data, predicted performance, interface requirements and construction features of all Contractor furnished equipment. The accuracy of such information and the compatibility of such information with overall performance requirements specified by Employer are the sole responsibility of the Contractor.

5 E1-GRD-5/5 C.2 Environmental Considerations C.2.1 In accordance with Paragraph of the General Technical Requirements and the Technical Data Sheets of Section E.1.1, the operating environment for this installation _(will, will not ) affect the life expectancy of the components used in this equipment. If there will be an effect, the following components will be affected as follows: Component Effect C.3 Other Technical Data for the Grounding Equipment and Materials a. Country of Origin 1. Overhead ground wire 2. Copper ground conductor 3. Ground rods 4. Shield wire accessoreis: a. Tension clamps b. Suspension clamp c. Parallel groove d. Lightning rods 5. Grounding connector materials b. Manufacturers 1. Overhead ground wire 2. Copper ground conductor 3. Ground rods 4. Shield wire accessories: a. Tension clamps b. Suspension clamp c. Parallel groove d. Lightning rods 5. Grounding connector materials c. Weight of heaviest crate to be shipped, kg d. Size of largest piece to be shipped (L x H x W), mm Contractor s Data