TECHNICAL SPECIFICATION OF 11 & 33 KV PIN INSULATOR

1. SCOPE - This specification covers the design, manufacture, testing, supply and delivery of 11 KV and 33 KV Porcelain Pin Insulators for use on 11 KV and 33 KV overhead Power Lines.

2. STANDAND - Except where they conflict with specific requirement in the specification, the Pin Insulators shall comply with the Indian Standard Specification IS: 731-1971 and its amendments from time to time. The insulator conforming to any other internationally accepted standard which ensures equal or better quality than the standard mentioned above would also be acceptable.

3. ATMOSPHERIC CONDITIONS –

3.1 Reference atmospheric conditions at which insulators characteristics shall be expressed for the purpose of comparison shall:-Ambient Temperature - 20 Degree CentigradeBarometric Pressure - 1013 Milli barsAbsolute Humidity - 11 gms of water per cubic meter corresponding to

63 percent relative humidity at 20 Degree Centrigrade

Note: - A pressure of 1013 milli bars is equivalent to a pressure of 750 mm of Mercury at 0 degree centigrade.

3.2 Tests for the purpose of this standard shall preferably be carried out under conditions ofTemperature and humidity specified in IS:196-1966(i.e. at a temperature of 27+ 2 degree centigrade and relative humidity of 66+2 percent) and at the prevailing atmospheric pressure. When this is not possible, test may be carried out under conditions naturally obtained at the time of the test. The barometric pressure, air temperature and humidity shall be recorded for the purpose of correction.

Corrections of test voltage for atmospheric conditions are given in Appendix A of IS: 731-1971.

4. The Thimble for 11 KV Pin Insulator should be suitable for use with Galvanized Steel Pins conforming to reference S-165 of IS: 2486 (Part-II) of 1974 with shank length 150 mm which is provided with a small steel head. Similarly, the thimble of 33 KV Pin Insulator should be suitable for use with 33 KV Galvanized steel Pins conforming to reference with shank length of 150 mm and with large head of ISS-2486 (Part-II) of 1974.

5. INSULATOR CHARACTERISTICS:-The insulator shall have the electrical and mechanical characteristics which are given below.The test voltage of insulator shall be as under:-

SN Description 11 KV Pin Insulator

33 KV Pin Insulator

1 Highest system voltage (rms) 12 KV 36 KV

2 Wet Power frequency withstand voltage testfor one minute (rms)

35 KV 75 KV

3 Visible discharge voltage (rms) 9 KV 27 KV4 Power frequency puncture withstand

voltage (rms)105 KV 180 KV

5 Impulse withstand voltage 75 KV (Peak) 170 KV (Peak)

(In the above standards, power frequency voltage is expressed as peak values divided by 2 and impulse voltage is expressed as peak value)

6. The withstand and flash over voltage are referred to the reference atmospheric conditions.7. Mechanical Loads –

SN Insulators Minimum Failing Loads1 11 KV Pin Insulator 5 KN2 33 KV Pin Insulator 10 KN

8. DIMENSIONS AND CREEPAGE DISTANCE:-The insulators shall have the following dimensions and minimum creepage distance for a moderately polluted atmosphere:-

SN Particulars 11 KV Pin Insulator 33 KV Pin InsulatorA Dimension

1) Height 130 MM 210 MM2) Diameter 125 MM 275 MM

B Creepage distance 230 MM 580 MM

9. TESTS: - The insulator shall comply with the following tests as per IS-731-1971.9.1 TYPE TESTS:- The following constitute the type tests :-

a) Visual examinationb) Verification of dimensionsc) Visible discharge testd) Impulse withstand voltage teste) Wet power frequency withstand voltage testf) Temperature cycle testg) Mechanical failing load testh) Puncture testi) Porosity testj) Galvanizing test.

Type test certificate from recognized Govt. lab for the tests carried out on prototype of same specifications shall be enclosed. The type test certificates shall not be more then 5 years old.

9.2 ROUTINE TESTS:- The following shall be carried out as the routine tests:-a) Visual examinationb) Electrical Routine testsc) Mechanical Routine tests

9.3 ACCEPTANCE TESTS:-The test samples after having withstood the routine tests shall be subjected to the following acceptance tests in the order indicated below:-

a) Verification of dimensionsb) Temperature cycle testc) Mechanical failing load testd) Puncture teste) Porosity testf) Galvanizing test

9.4 Tolerance in insulator dimensions shall be as per the relevant Indian Standard i.e. ± (0.04d+1.5) mm when d ≤ 300 mm and where d is the dimension in mm.

10. MARKING:-Each insulator shall be legibly and indelibly marked to show the followings:-a. Name and trade mark of manufacturerb. Month and year of manufacturec. Minimum failing load in newtons

9.5 d. Country of manufacture