Success Story: Testing and Maintenance of Electrical Equipment at a Steel Manufacturing Plant

Studies show that in 2019, India was the world’s second largest producer of crude steel with a capacity of 111.2 MT. India’s finished steel consumption is also projected to rise from 99 MT (2018-19) to 230 MT by 2030-31. Furthermore, with the government’s view towards self-reliance, steel companies are ramping up steel production capacity. Therefore, the steel industry is set to reinforce its importance as a major contributor to India’s economic growth and development. With this in mind, it is important that critical electrical assets in steel manufacturing plants undergo regular maintenance.

In this blog post, we will discuss how SCOPE’s services vertical – ISOSCELES Sales & Services Pvt. Ltd (ISSPL) successfully carried out testing and maintenance of following items at the manufacturing plant of a leading Indian steel manufacturer:

• 220/33kV and 33/6.6kV power transformer Testing
• power transformer Maintenance
• 33 kV and 6.6 kV switchboard Maintenance
• 33 kV and 6.6 kV switchgear Testing
  • VCB Testing
  • CT PT Testing
  • Numerical Relay Testing
  • Surge Absorber Testing
  • 220KV Lightening Arrestor Testing
  • 220kV CVT Testing
• 220 kV GIS equipment Testing
  • SF6 CB, Disconnector and Earth Switch Testing
  • GIS CT PT Testing
  • CRP Panel Relay Testing

ISSPL Mandate

One of the leading manufacturers of steel products in India, having a 1.5 MT greenfield integrated steel plant in Jharkhand, empaneled ISSPL to facilitate Testing and Maintenance of electrical assets at the steel plant. The mandate included complete testing and maintenance of 20 substations including 50 nos of 220/33kV and 3.3 kV/6.6 kV transformer maintenance, 28 sets of 33 kV and 6.6 kV switchboard maintenance, 152 nos of 33 kV and 6.6 kV switchboard panel testing – including complete test of current transformer, circuit breaker, numerical relay, line and bus power transformer, SA, etc, 21 nos of 220/33kV and 33/6.6 kV transformers, 7 nos of 220 kV GIS substation bays and 12 numbers of lightning arrestor and CVT testing.

Testing and Maintenance Done

After examining the site, ISSPL service experts performed the following tests:

1. Transformer Maintenance: transformer cleaning, tightness checking of all hardware accessories, IR and PI checking of transformer, healthiness and functional check of all the transformer mechanical protection devices (OTI, WTI, etc) with simulation of the breakers, arresting of oil leakage, if any, cleaning of NGR panel and checking the healthiness of its resistance and CT
2. 33 kV and 6.6 kV Switchboard Maintenance: cleaning of the breaker, bus top cover, breaker panel and bus duct, tightness checking of the switchboard main bus, checking of tightness of control and power cables, checking the functioning of the earth switch, lubrication of breaker mechanical parts, IR test of main test and the breaker, checking the healthiness of the closing/tripping coil and spring charging motor and checking of bus bar contact resistance.
3. 220/33 kV and 33/6.6 kV Transformer Testing: stable/unstable condition for differential protection relay, test & enable REF protection, wiring check of 33kV outgoing VCB, 6.6 kV and 33 kV incoming VCB and CT& transformer and healthiness check of all protective accessories mounted on transformer for tripping.
4. 33 kV and 6.6 kV VCB Testing: electromechanical operation test of circuit breaker and measurement of opening & closing time, etc. Furthermore, wiring check of switchgear, insulation test & CRM test was also done.
5. CT Testing: verification of terminal markings and polarity, over voltage inter-turn test, ratio test, VA burden, accuracy class, knee point and IR test
6. PT Testing: IR, winding resistance, ratio test, polarity test, fuse continuity test and control wiring check
7. Numerical Relay Testing: relay secondary injection test by conventional 3 phase current test set, protection, control and annunciation scheme checking.
8. Surge Absorber Testing: Residual voltage test, operating duty test and IR test
9. 220 kV Lightning Arrestor Testing: residual voltage test, operating duty test and IR test
10. 220 kV CVT testing: IR test, ratio test, polarity test, winding resistance and fuse continuity test     

The scope of work in this project also included testing and maintenance of 220 kV GIS substation equipment. These include:

1. Electromechanical operation test of circuit breaker, disconnector and earth switch+, CO OCO timing and DCRM test, spring charging time and consumption of motor operating mechanism, CRM and IR tests.
2. Operating test of circuit breaker at rated and lowest SF₆ gas pressure, mechanical operation endurance test of circuit breaker, disconnector, earth switch and measurement of operating parameters and wiring check of switchgear by simulation method
3. 220 kV GIS current transformer testing: verification of terminal markings and polarity, ratio test, knee point test, VA burden, IR test and secondary winding resistance test
4. 220 kV GIS voltage transformer testing: verification of terminal markings and polarity, over voltage inter-turn test and test for ratio, VA burden and accuracy class
5. 220 kV CRP panel relay testing: relay secondary injection test by conventional 3 phase current test set, control scheme, anunciation scheme check and relay testing with 3 phase secondary injection kit

Challenges faced during Execution

At the time of order finalization, quantity of substation devices under test was not clear. Furthermore, due to issues pertaining to accommodation, quality of food and local conveyance to and from the site location, our work was behind schedule. In response to these challenges and keeping in mind the commitment made to the customer, our service experts reoriented work strategy by engaging creative solutions. We replanned manpower in such a manner that work would be ongoing continually through the day without any interruption. In this manner, we ensured that the work was completed within the stipulated timeframe of 12 days.

Summing Up

ISSPL Team successfully completed the testing and maintenance works at the steel manufacturing plant within the agreed timeline. This project enabled ISSPL to diversify its customer base beyond electrical utilities. To know more about ISSPL’s testing capabilities, please write to us at marketing@scopetnm.com.