The existing 3x Sag Mill Cycloconverter transformer utilised a loop in loop out cable supply arrangement (instead of dedicated supply to each transformer). This has cramped the 33kV termination box, particularly as the existing cables utilised are 300mm2 Cu 19/33kV three core ind.screened PVC/SWA/PVC Sheathed. This resulted in high levels of Partial Discharge between the various cores as they were not meeting the 33kV minimum clearance requirements at the various points of the termination / cable core tails.
ERM Consulting were engaged to re-design and re-construct the cable entries and the termination box / busbar arrangement to maximise clearances (compliant to Australian Standards – AS2067) and re-terminate all cables.
ERM Consulting produced a detail Scope of Work document as well design drawings and successfully executed the works on site. The works were safely carried out during a designated Train / Process Plant shutdown on time and on budget.
The transformers were also tested during this process. The tests included DLA, Capacitance, Winding Ratio, SFRA, Winding Resistance Tests.
Methodology
ERM Consulting conducted the design and engineering work in such a manner to allow for flexibility during the install phase of the project. We all know that in-service assets tend to deviate from the existing “design drawings” when it comes to bolt patterns and other critical measurements. Our approach enabled the install process to be easier, safer and flexible.
Application of the solution
ERM Consulting delivered this project at no delay to our client. This ensured the end user in the Pilbara region of Western Australia remained confident and satisfied to put the transformer in service. A great result for the entire team.
Conclusion
The delivery of this project resulted in safely returning this transformer to service. Safety is a value that ERM Consulting take very seriously and shortcuts are NOT tolerated by ERM Consulting in this regard.
