Medium to low voltage transformers are the final, crucial link in transmitting power from the National Grid to the functional equipment, so the impact on a business of a transformer failure can be very significant. Sulzer was recently contracted to complete a refurbishment after the client was given a prohibitive lead time for a new transformer by the original equipment manufacturer (OEM).

Redcar Port, owned and managed by Redcar Bulk Terminal (RBT), is situated on the South bank of the River Tees and handles a wide range of bulk cargoes. It is the deepest port on the East coast of the UK and operates 24/7 all year round, with equipment capable of unloading in excess of 44,000 tons in a working day. As such it has a significant reliance on electrical power in order to maintain efficient operation.

RBT has worked with Sulzer over many years and they have formed a good working relationship, especially with the Middlesbrough Service Center which is situated very close by. So, when an 840 kVA transformer failed with a primary winding shorted to earth, the first call was to Sulzer so that the problem could be investigated and resolved at the earliest opportunity.

Initially, the Sulzer engineers were contracted to investigate the cause of the fault and to provide an initial report with recommendations for the best course of action. Ordinarily the quickest, if not the cheapest, repair is a direct replacement but unfortunately 3.3 kV transformers are not always available on short lead times.

For this particular application the most efficient resolution was a complete refurbishment that would effectively deliver a virtually new transformer back to RBT. Fortunately, Sulzer service centers are fully equipped with both the facilities and the engineering expertise to complete these projects in-house, giving the client peace of mind. Steve Bonner, Electrical Maintenance Engineer at RBT, comments:“Transformers such as this one provide power to a wide range of equipment so any failure will have some significant consequences for us in terms of productivity. Clearly, speed of repair is crucial, especially if we need to hire large generators to keep the plant operating." Arthur Grant, Service Center Manager at Middlesbrough adds:

“For this particular project it was necessary to develop new formers and racking in order to create the new windings with exactly the right dimensions. This is very important because in this design of transformer the low voltage windings sit inside the high voltage windings and they share the laminated core.” Once a new winding has been finished it is tested before being assembled with the other windings to create a high voltage circuit which is connected in star configuration and a low voltage circuit connected in delta. The new coils are located on the laminated core and then tested again to ensure the correct connections have been made and the insulation is meeting the required standards.

The Middlesbrough Service Center completed the project as quoted, with an 8 week turnaround, compared to a lead time of several months for a new transformer. Arthur Grant concludes: “We have a close working relationship with RBT that has been built up over many years. Being located almost next door means that their engineers can easily come in and review progress on any project. We communicate on a regular basis about the progress of any repairs which means the client can plan accordingly and use their resources more efficiently.”