March 2017, by 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 GErecently 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 challenge.
One of the main challenges in this project was to match weights and dimensions to those of the existing unit. 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 will allow the user to connect the unit in the bank to function optimally with the other units.
The unit completed tests sucessfully on last December. This is an example of how at Prolec GE we work with a strong focus on our customers. We solve technical challenges that arise from their special needs, always looking to exceed their expectations. Not only we can provide standardized and simplified solutions, but we can also develop specific designs that fit the most challenging customer requirements and constraints. For this, we count on 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.
Please ask the experts in Prolec GE if you require any special technical solution in your plant or substation.