Power Track

Publication 301a-1997 peoples Republic of Bangladesh standard For lightning Arresters 1. scope: this Standard Establishes the Physical and Performance Requirements of Surge Arresters. Reb Arresters Shall Include Station Intermediate and Distribution Classes to Be Used On 33 Kv and 11 Kv Systems Respectively, and Shall Be Provided Gapless Valve Elements. 2. General : reb Arresters Shall Protect Substation and Pole Mounted Equipment from Voltage Impulses or Surges Resulting from Lightning Strokes, System Faults, Circuit Switching, Load Rejection or other Events. the Arresters Shall Limit such Over Voltages to Voltage Levels Below Equipment Bil Ratings. 3. service Conditions: reb Arresters Shall Meet the Following Physical and System Conditions: a. Ambient Temperature Above 40oc b. Maximum Relative Humidity 90 % c. Altitude Up to 1, 000 Meters Above Sea Level d. Nominal System Frequency 50 Hz 4.1. System Parameters: A. Nominal Voltage 11 Kv 33 Kv B. Maximum System Voltage 12 Kv 36 Kv C. System Frequency 50 Hz 50 Hz D. Number of Phase 1 / 3 3 E. System Fault Level 13.1 Ka 16 Ka F. Bil 95.0 Kv 200 Kv 4.2. Technical Requirements: the Surge Arrester Shall have the Following Protective Characteristics A. Rated Voltage(rms) 9/9 Kv 33/36 Kv B. Max Continuous Operating Voltage (mcov) 7.65 Kv 29 Kv C. Standard Nominal Discharge Current (8/20 Micro Second) 5/10 Ka 5/10 Ka D. Lightning Impulse (8/20 Micro Second) Maximum Residual Voltage 35 Kv 110 Kv E. Impulse Withstand Level On the Arrester Housing. i) Lightning Impulse Voltage 95 Kv 200 Kv ii) Power Frequency Voltage (dry) 35 Kv 95 Kv iii) Power Frequency Voltage (wet) 30 Kv 80 Kv 5. Construction: 5.1 Reb Arresters Shall Be Gapless Type Described Briefly as Follows: a. gap Less Arresters Shall have Elements of Zinc Oxide to Perform Both the Surge Discharge and Power frequency Reseal Functions. B. 9 Kv Distribution Type Arrester Must Include An Isolator to Provide Positive Isolation and Visual Identification if Arrester Becomes Damaged Internally. 5.2 Insulators a. Arresters Shall Be Protected in a Hermetically Sealed Wet Process Porcelain or Polymer Jacket, Which Shall have a High Creepage Distance and a High Dielectric Strength, as Specified in Article 6 & 7 Below. 5.3 Connectors A. Both Line Lead and Isolator Terminals of Distribution Class Arresters Shall Accommodate # 6 solid Through 1/0 Awg Stranded Copper or Aluminum Conductors. b. the High Voltage Terminal of Sub-station Class Arrester Shall Accommodate 1/0 Through 4/0 Awg Mhd Bare Copper or Aluminum Conductors. the Ground Terminal Shall Accommodate 1/0 Awg Mhd Bare Copper or Aluminum Conductor. the High Side Voltage Terminal to Be Provided On the Top of the Arrester and Both the Line and Ground Terminal Shall Be a Two-hole or Four-hole Standard Pad Nema Connector. 6. Protective Characteristics: reb Arresters Shall have the Following Protective Characteristic Based On per Unit Crest Arrester Rating as Summarized from Ansi C 62.22 , and the Protective Level (kv) is Based On the Following Formula; Protective Level Equals the per Unit Level X Arrester Rating X Square Root of 2. the Existing Datas are Proposed to Be Replaced By the Followingtable 1 & 2. table-1 station and Intermediate Class Arrester Characteristics station Class steady State Operation System Voltage & Arrester Ratings protective Levels Range if Industry Maximum per Unit crest of Mcov maximum System Voltage L-l (kv/rms) minimum System Voltage l-g (kv/rms) minimum Mcov Rating duty Cycle Rating (kv/rms) 0.5 Micro Sec Discharge Voltage (dv) 8/20 Micro Sec Wave Dv switching Surge-dv maximum High-amp Withstand Crest Amps 13.1 7.56 7.65 9-12 2.33-2.48 1.97-2.23 1.70-1.85 6500 13.9 8.03 7.65 9-15 2.33-2.48 1.97-2.23 1.70-1.85 6500 36.2 20.90 22 27-36 2.43-2.48 1.97-2.23 1.70-1.85 6500 intermediate Class 4.37-169 2.52-97.57 2.8-98 3-144 2.38-2.85 2.28-2.55 1.80-2.10 6.500 table 2 distribution Arrester Protective Characteristics distribution Class steady State Operation System Voltage & Arrester Ratings Crest of Mcov protective Levels Range if Industry Maximum per Unit crest of Mcov fow Protective Level Discharge Voltage with 8/20 Micro Sec Wave maximum system voltage l-l (kv/rms) minimum system voltage l-g (kv/rms) minimum Mcov rating duty Cycle rating (kv/rms) 5 Ka nd 10 Ka hd 5ka nd 10 Ka Hd 13.1 7.56 7.65 9 33.5-36 26.5-35.3 30.0-33.5 21.7-31.5 13.9 8.03 8.4 10 36.0-37.2 29.4-39.2 31.5-33.8 24.5-35 36.2 20.90 24.4 30 107.0-108 85.0-109.5 94.5-99 71.8-99 36.2 20.90 29 36 125 99.0-136 116.0 83.7-125 mcov= Maximum Continuous Operating Voltage nd= Normal Duty hd= Heavy Duty 7. Performance Tests: reb Distribution Arrester Characteristics Shall Meet the Requirements of Ansi C62.22 with Their Performance Determined By Tests Described in Ansi C62.11 and Summarized Below: 7.1 voltage Withstand Tests to Demonstrate that the Arrester Insulation is Capable of withstanding Impulse and Power Frequency Over Voltage. 7.2 power Frequency Spark Over to Ascertain that the Spark Over Voltage At Power Frequency Exceeds the Rated Voltage By a Specified Margin. 7.3 discharge Current Withstand Tests to Determine the Adequacy of the Electrical, Mechanical and Thermal Design of the Arrester Under High Current Short Duration and Low Current Long Duration Conditions. 7.4 impulse Spark Over Voltage Time Characteristics to Establish the Relationship Between the Impulse Spark Over Voltage and the Time to Spark Over for the Following Impulse Wave Shapes: a. front of Wave b. 1.2 / 50 Micro Second Wave Shape c. slow Front (switching Surge) d. maximum Spark Over 7.5 discharge Voltage Tests to Determine the Relationship Between the Voltage Arrester Terminals and An 8 / 20 Micro Second Discharge Current Wave. 7.6 duty Cycle Test to Determine the Ability of the Arrester to Successfully Interrupt Follow Current Repeatedly. 7.7 radio Influence Voltage Test to Determine the Amplitudes of High Frequency Voltages that Can Interfere with Communication Circuits. 7.8 internal Ionization Voltage Test to Determine the Ionization Current Levels that Can Cause Arrester Deterioration. 7.9 pressure Relief Tests to Demonstrate that Failed Arresters Will Not Disintegrate Violently When Exposed to High Fault Currents. 7.10 surface Contamination Tests to Demonstrate that the Arrester Can Withstand the Electrical Effects of Contamination On the Arresters Exterior Surfaces. These Tests Shall Be Conducted At the Highest Voltage Rating of the Distribution Type Arrester. 8. nameplate: information Required for Identification Must Be Embossed On a Nameplate Firmly Fixed to the Arrester and Shall Include: a. arrester Classification b. manufacturers Identification or Symbol c. arrester Model and Identification Number d. arrester Voltage Rating e. date of Manufacture the Nameplate Must Be Legible Over the Lifetime of the Arrester. 9. mounting: reb Distribution Arresters Shall Be Supplied with a Cross Arm Mounting Bracket that Conforms to the Requirements of Nema Pub. No. Ph25. reb Intermediate & Sub-station Class Arresters Shall Be Equipped with (3) 14-22 Mm Dia Slots (120 Degree Apart), 222-254 Mm Dia Bolt Circle Equipment/ Structure Mounting Arrangement. all Mounting Bolts and Conductor Connections Require Lock Washers. Lock Washers Shall Be Fabricated from Material that Comply with the Requirements of Ansi B18.21.1. 10. Finish: all Exposed Steel or Iron Parts of the Arrester Except Threaded Parts Smaller Than 3 Inch in Diameter, Shall Be Hot Dip Galvanized in Accordance with Astm A153. 11. Inspection: the Manufacturer Shall Conduct the Tests Described in Section 7 of this Standard, On Samples of Reb Distribution Arresters, to Verify that They Meet the Design Requirements and Performance Characteristics Detailed in Ansi C 62.22 and Summarized in this Standard. Reb Reserves the Right to Witness Factory Tests, and Shall Request Test Reports. in Case of Purchasing Order More Than 10, 000(ten Thousand) Pcs Then the Bidder/manufacturer have to Perform all the Tests Described in Section 7 of this Standard On Samples of the Arresters. if the Order is Less Than 10, 000 Pcs Then Reb May Accept Design/type Test Report Performed from An Independent Testing Laboratory and Only the Routine Test/acceptance Test Shall Be Performed On Samples Subject to the Fulfillment of the Conditions Stated in Section 12.5.3 : Product Retest Requirements of Ansi 62.11 1993. 12. Packaging: reb Arresters Shall Be Securely Packaged for Shipping. Each Package Shall Be Clearly Marked with the Manufacturers Name, Catalog Number and Reb Item Number. 13. other Standards: the Performance and Design Requirements of Reb Distribution Arresters, Based On other Internationally Recognized Standards, are Acceptable Only if the Requirement of such Standards are Equivalent to or Exceed the Requirements Quoted in this Document. all Accompanying Drawings are Conceptual. the Manufacturer is Responsible for Preparation of Drawings and a Design Which Meets the Dimensional, Strength, and other Performance Requirements of this Standard. the Text, Figures and References to other Standards Supplement Each Other, and Shall Be Considered Parts of this Standard. 14.bibliography of Reference Standards: (latest Edition) 1. Ansi/ieee C62.22: American National Standard Guide for the Application of Metal-oxide Surge Arresters for Alternating Current Systems. 2. Ansi C62.2: American National Standard Guide for the Application of Valve Type Surge Arresters for Alternating-current Systems. 3. ansi/ieee C62.11: Ieee Standard for Metal Oxide Surge Arresters for Ac Power Circuits. 4. Ansi/ieee C62.1: Ieee Standard for Surge Arresters for Ac Power Circuits. 5. nema Pub. No. Ph25 : Eei Nema Standard for Secondary Extension Brackets. 6. ansi/astm A153: Standard Specification for Zinc Coating (hot Dip) On Iron and Steel Hardware. 7. ansi B18.21.1: American National Standard for Lock Washers.