Purchase of transformers under scanner

Tribune News Service

Patiala, June 20

The recent purchase of transformers has raised eyebrows as many of these have developed snags in various parts of the state.

A 500MVA power transformer was damaged last week at Punjab State Transmission Company Limited (PSTCL), 400KV sub-station, Rajpura. The transformer was supplying power to Dera Bassi and Banur areas. However, there is no disruption of power as alternative transmission system has been used.

The transformer was commissioned in the last week of March. Within one week, the corona ring was damaged, while the 500MVA transformer was under commissioning at the Rajpura sub-station.

It may be mentioned that two 500MVA transformers at the 400 KV Dhuri sub-station were damaged in October 2015 due to excessive formation of dangerous gases. First transformer was repaired at the manufacturer works and it took about one year.

"According to PSTCL engineers and their consultant power grid of India, there was some design defect in transformers. It is not understood why replacement of these transformers was sought when the transformers were damaged in warranty period," said a retired PSPCL engineer.

The commissioning of third transformer at Dhuri has been held up for the last one year because of some civil design problem. The Chief Engineer, Transmission, in his letter of June 26, 2016, had asked the SE/civil design to fix the responsibility for this major lapse in designing.

For dispersing the power generated by 1980MW T Sabo Thermal Station and 1400 MW Rajpura Thermal Station, the PSTCL had given the contract to design and construct the 400 kV system of Punjab, as the existing system was at 220 kV only. The key elements of these 400 kV stations were the giant 500 MVA power transformers of 400/220 kv rating. Thus, the thermal power injected at T Sabo and Rajpura would be stepped down to 220 kV and injected into PSTCL 220 kV grid.

It is during the paddy season that the thermal power injection at Rajpura and Talwandi Sabo is maximum, and so the 500 MVA transformers of 400/220 kv class get loaded mainly in paddy season.

The Rajpura transformer appears to have failed just at the start of paddy season which indicates that there was some serious manufacturing defect. The manufacturer should be asked to explain the failure and attend it free of cost or else the manufacturer should be blacklisted for poor performance. Senior officials were available for comments on the issue.