Impulse & Power Frequency Test Laboratory

Impulse & Power Frequency Test Laboratory consists of an indoor laboratory and an outdoor laboratory test bay. Indoor laboratory is a high voltage test hall of dimensions 50m x 40m x 35m housing a 3MV, 150kJ impulse generator which has 15 stages and is generally used for carrying out lightning impulse voltage and switching impulse voltage tests on high voltage equipment of rating upto 550kV. The generator is also suitably configured with series and parallel combinations of capacitors, resistors and an additional inductor to generate the impulse currents necessary to be passed through the surge arrester for measuring the residual voltage. Apart from this, the division has a rain making equipment and power frequency testing transformers of ratings a) 100kV, 50mA and b) 600kV, 2000kVA.

The outdoor test bay consists of a 1800kV, 2000kVA cascade transformer comprising of three 600kV, 2000kVA transformer units. The AC test voltage up to 800 kV from the outdoor bay can be taken into the high voltage test hall by means of a wall bushing. This setup is used for conducting power frequency voltage tests (Dry & Wet) and RIV & corona tests up to and including 500kV.

With the equipment installed at present, it is possible to undertake following tests on all major electrical equipment like power transformers, current transformers, potential transformers, air break switches, disconnectors, outdoor UG cable terminations, bushings, insulators power line accessories etc. up to and including 550 kV system.

Major test, measurement and calibration equipment available are:

• Indoor Impulse voltage generator of 3 Millionvolts, 150 kJ.
• Outdoor Power frequency Cascade Transformers setup of 1800kV, 2000KVA (3 nos. of 600 kV each)
• Indoor Power frequency Transformers each of (i)50 kV 100 KVA (ii) 100 kV, 10 KVA  and          (iii) 600kV 2000KVA.
• 550 kV, 2 nF Partial discharge free coupling capacitor
• 4-Channel High Resolution impulse Analysing system of 120 M samples/ sec per channel. 
• 1GHz Steep front impulse measuring system.
• One meter sphere gap capable of measuring of 1MV (Impulse & Power frequency voltages) as per standards.
• 50 tonne Universal Testing Machine
• Hot & Cold bath for temperature cycle test upto 220kV

3 Millionvolt, 150 kJ, Impulse Voltage Generator

3MV, 150kJ capacity Impulse Voltage Generator has 15 stages and is generally used for dielectric testing. The generator is also suitably configured with series and parallel combinations of capacitors, resistors and an additional inductor to generate the impulse currents necessary to be passed through the surge arrester for measuring the residual voltage.

1800kV, 2000 KVA, Power Frequency Testing Transformer

This cascade transformer setup is used for carrying out power frequency voltage tests (Dry & Wet) and pollution tests. Facilities are also available for taking supply into the main laboratory for indoor tests.

600kV, 2000kVA Power Frequency Testing Transformer

This setup is used for conducting power frequency voltage tests (Dry & Wet) and RIV & corona tests up to and including 500kV.

Tests conducted :

This Laboratory can undertake the following tests as per National & International Standards:

• Lightning impulse voltage tests up to 2,400 kV (Peak) level.
• Switching Impulse Voltage Dry & Wet Tests up to 1.5 MV peak level.
• Steep front impulse voltage test on polymer insulators of length up to 500mm and porcelain insulators up to and including 33 kV insulators.
• Corona Inception and Extinction Test and RIV measurements up to & including 500 kV system
• Power frequency voltage Dry & Wet withstand tests up to 1,000 kV (rms) level
• Porosity test on porcelain insulator fragments.
• Mechanical performance/Electro-Mechanical test up to 400 kN on porcelain insulators.
• Mechanical performance/mechanical test up to 400 kN on polymeric insulators.
• Thermal mechanical load cycle tests.
• Under oil puncture test for porcelain insulators up to and inclusive of 33kV rating.
• Temperature cycle test on insulators up to & including 220kV rating.
• Surge withstand test.
• Voltage distribution tests on insulator strings
• DC withstand & flashover tests for insulating material under dry/oil  condition up to 280 kV.