March 2017, by José Dávila Roque Leader of Technical Studies.

The process of manufacturing a retro-fit transformer with space constraints and specific dimensions undoubtedly becomes an important technological challenge that not every manufacturer can overcome 

Prolec GE recently manufactured a large, single-phase autotransformer rated 373 MVA for Duke Energy Corporation. This type of equipment is applied for transmission line links of 525 kV on the high voltage side and 240 kV on the low voltage side. This unit will serve as a replacement for one of three already existing units in a three-phase bank. Our customer required the autotransformer to be delivered in a maximum time of 11 months, which was a significant logistics and production challenge.

In order to complete this project, one of the main challenges was to match weights and dimensions to those of the existing unit. It was necessary to consider that the substation has constrained dimensions due to electric clearances to substation structures and firewalls. The tank base was designed to closely fit the existing pier foundation.

Besides the mechanical constraints, it was required to match impedances on seven  combinations of voltage values for high voltage and low voltage sides. For each guaranteed impedance value the acceptance tolerance was significantly lower than the value according to applicable standards. This is in  itself a very difficult requirement. However, applying highly accurate magnetic field calculations and tight control on manufacturing tolerances, the measured values during final lab tests fully complied with our customer’s specification. This performance allows the user to connect the unit in the bank to function optimally with the other units.

The final tests on the unit were completed successfully last December. This is an example of how at Prolec GE we work together to transform with a strong focus on our customers. We solve technical challenges that arise from their special needs, offering comprehensive solutions, always looking to exceed their expectations. 

Our offer is clear: not only can we provide standardized and simplified solutions, but we can also develop specific designs that fit the most challenging customer requirements and constraints; we have the talent of our personnel who at every step of the process do their work with extreme attention to detail, as one who makes a tailor-made suit to ensure the reliability of our transformers.

Should you require a special technical solution for your plant or substation, you can be sure you will receive expert and innovative support from Prolec GE.