Testing Activities

Testing Activities

The commercial and investigatory tests can be carried out as power national and international standards. The laboratory has been accredited by NABL in accordance with IEC 17025 : 2017.

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Testing Activities

  765 kV ACSR Hexagonal Zebra conductor erected for AC RIV and Corona test        800 kV ACSR Hexagonal Lapwing conductor erected for DC RIV and Corona test in test bay in progress near a HVDC Line

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Testing Activities

145 kV, Gas Insulated System in test bed 800 kV, 4000 A, 50 kA, SF6 Live Tank Circuit Breaker erected for AC RIV and Corona test

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Testing Activities

View of 1200 kV, Lightning Arrester during AC RIV test 800 kV, 3150 A, 50 kA, 50 Hz, Knee type Disconnector during dielectric test in test bay for RIV test

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Testing Activities

1200 kV Capacitor Voltage Transformer erected for dielectric test in test bay 400 kV AC Line Trap strung for RIV measurement

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Testing Activities

145 kV Current Transformer undergoing partial discharge test (orientation of photograph to be changed as above) 420 kV OIP Condenser Bushing undergoing partial discharge and long duration AC voltage test

± 500 kV HVDC Composite long rod silicone rubber “V” suspension insulator string arranged for DC pollution test by solid-layer method The following gives list of testing and investigatory activities of the unit asper NABL Scope

1. High voltage Switchgear and Control gear

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Testing Activities

1.1. High voltage switchgear & control gear and AB switches ratings up to 1200 kV system

a) Lightning Impulse voltage test. b) Switch Impulse voltage test (Dry & Wet). c) Power frequency voltage test (Dry & Wet). d) Radio interference voltage test (EMC). e) Mechanical endurance test. f) Artificial pollution test by salt fog method on insulators up to 800kV system. g) Corona Inception & Extinction voltage test. h) Visible Discharge test.

1.2. Alternating Current circuit breakers rating up to 1200 kV system.

a) Lightning Impulse voltage test. b) Switch Impulse voltage test (Dry & Wet). c) Power frequency voltage test (Dry & Wet). d) Radio interference voltage test (EMC). e) Artificial pollution test by salt fog method on insulators up to 800kV system. f) Corona Inception & Extinction voltage test. g) Visible Discharge test.

2. Inductors and Transformers

2.1. Reactor up to 1200kV system

a) Lightning Impulse voltage withstand test

2.2. Combined instrument transformer (up to 1200 kV system)

a) Lightning Impulse voltage test b) Power frequency voltage test (Dry & Wet)

2.3. Current transformer (up to 1200kV system)

a) Tests for Accuracy b) Temperature rise test c) Enclosure tightness test at ambient temperature

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Testing Activities

d) High voltage power frequency test on primary winding e) High voltage power frequency test on secondary winding f) High voltage power frequency wet withstand voltage test on outdoor Current Transformer g) Measurement of capacitance and Dielectric Dissipation factor (Tan Delta) for liquidimmersed Current transformer h) RIV test i) Partial discharge measurement test

2.4. Voltage transformer & capacitor voltage transformer (up to 1200 kV system)

a) Tests for Accuracy b) Temperature rise test c) Enclosure tightness test at ambient temperature d) High voltage power frequency withstand tests on primary terminals (on external insulationwet test) e) Verification of terminal markings & polarity f) High voltage power frequency withstand tests on secondary terminals g) Ferro resonance test and transient response test h) Short circuit withstand capability test (except PD measurement) i) Chopped Lightning Impulse voltage test on primary winding j) Switching Impulse voltage withstand test on Capacitor voltage transformer k) RIV test l) Measurement of transmitted over voltage m) Measurement of capacitance and dielectric dissipation factor (Tan Delta) on capacitorvoltage transformer n) Measurement of high frequency capacitance & Equivalent series resistance measurement o) Measurement of stray capacitance and conductance measurement p) Corona test q) Partial discharge measurement test on capacitor voltage transformers

2.5. Power / Distribution / Traction/Auto transformers up to 1200 kV system

a) Separate source voltage withstand test b) Measurement of dielectric dissipation factor (Tan Delta) and capacitance of the windings c) Lightning impulse voltage withstand test (dry) d) Chopped lightning test e) Transfer surge test

3. Transmission line equipment and line accessories

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Testing Activities

3.1. Hollow insulator, post insulator (indoor/Outdoor) up to 1200 kV system

a) Lightning Impulse voltage withstand test b) Dry or Wet Power frequency voltage withstand test c) Dry or Wet Power frequency voltage flashover test d) Switching Impulse voltage withstand test (Dry & Wet)

3.2. HV Fuses (Horn Gap) up to 33 kV system

a) Lightning Impulse voltage Dry test b) Power frequency voltage dry and wet test

3.3. Porcelain insulators for over head power lines with nominal voltage greater than 1000 V,insulator string, post insulators, solid core insulator, composite insulators, pin insulator,Polycrete housings up to 1200 kV system

a) Visual Examination Verification of Dimensions b) Visible discharge test c) Dry Power frequency voltage withstand test and Flashover test d) Wet power frequency voltage withstand test and Flashover test e) Voltage distribution test (as per customer request) & power frequency puncture test f) Lightning Impulse voltage withstands test (Dry) and 50% impulse voltage flashover test. g) Switching Impulse voltage withstand test (Dry & Wet) h) Corona inception and extinction voltage test i) Artificial pollution test by salt fog method

3.4. High voltage insulators up to 1200 kV system

a) Radio Interference voltage test

3.5. Surge Arrester for alternating current systems up to 1200 kV system

a) Power frequency voltage withstand tests of arrester housing (Dry & Wet) b) Lightning Impulse voltage test on arrester housing (Dry) c) Switching Impulse voltage test on arrester housing (Dry & Wet) d) RIV test e) Corona test

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Testing Activities

f) Contamination/Pollution test on Lightning Arrester

3.6. Bushing for alternating voltage up to 1200 kV system

a) Dry Power frequency voltage withstand test b) Wet Power frequency voltage withstand test (on outdoor, outdoor-indoor and outdoor-oilImmersed busing of which units up to 245kV) c) Lightning impulse voltage withstand test (Dry) and 50% impulse voltage flashover test. d) Switching impulse voltage withstand test (Dry & Wet) e) RIV test f) Measurement of dielectric dissipation factor and capacitance at ambient temperature g) Corona test h) Artificial pollution test by salt fog method i) Partial discharge test j) Long duration AC voltage withstand test

3.7. Aluminium conductor for overhead transmission lines connectors & clamps up to 1200 kVsystem

a) Radio Interference voltage test b) Corona inception and extinction voltage test

3.8. On load tap changer & tap changers

a) Power frequency voltage test b) Lightning impulse voltage withstand test

3.9. Coupling capacitor divider up to 1200 kV system

a) Lightning impulse voltage test on arrester housing (Dry) b) Switching impulse voltage withstand test (Dry & Wet) c) Discharge test d) Measurement of capacitance and dielectric dissipation factor (Tan Delta) e) High frequency capacitance and ESR measurements f) Stray capacitance and conductance measurements

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Testing Activities

3.10. Insulators and similar equipment up to 800 kV DC system

a) Dry and Wet DC voltage withstand and flashover test b) Dry DC voltage long duration withstand test c) Wet DC voltage long duration withstand test d) RIV test e) Corona test f) Lightning impulse voltage test g) Dry and Wet switching impulse voltage test h) DC pollution test by solid layer method

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