Maintenance free and worry free for many years - thanks to OLTC retrofit
New VACUTAP® VM® ensures Tata Steel Manufacturing operational reliability for years to come
What do you do if your transformer is in good condition, but the on-load tap-changer (OLTC) is at the end of its service life after more than 4,000,000 switching operations in an arc-furnace application? This was the question facing SISCO Plant, a company of the Tata Steel Manufacturing (Thailand) group. The answer from Reinhausen (Thailand) Ltd. was the on-site installation of a maintenance-free VACUTAP® VM® in combination with a general refurbishment of the 42 MVA furnace transformer from the Italian manufacturer Tamini.
In the first step of the work, the oil was drained from the OLTC and transformer so that the manholes could be opened and the heart of the transformer - the on-load tap-changer - could be accessed. Then the actual replacement started: The old OILTAP® M including drive shafts and motor-drive unit was dismantled, and the new VACUTAP® VM® with motor-drive unit was installed. Moreover, the Reinhausen Thailand service team replaced the pressure relief device (PRD) of the transformer with a new and reliable unit from CEDAPSE, cleaned the oil conservators and the piping, and replaced the gaskets of all high-voltage bushings. The oil was then reconditioned, and the transformer was refilled under vacuum. Finally, our specialists carried out mechanical and electrical test operations over the entire control range, conducted an oil analysis, a resistance measurement, and ratio and insulation tests, and prepared the service report with all the important details for the customer.
The average temperature of 45 degrees Celsius in the transformer room made the colleagues sweat quite a bit. And no crane could be set up in the transformer room, so moving all of the heavier components had to be managed by chain block and muscle power. And due to the leaks of the bushings, the colleagues had to clean the transformer extensively. But thanks to perfect coordination to carry out the work in parallel while observing all applicable safety regulations, the colleagues mastered the numerous challenges perfectly and were able to complete the project on time.
A big surprise was the visit of the Vice President of Tata Steel (Thailand), who was able to get a personal impression of our professional and high quality work on site. This positive impression in combination with further discussions on site convinced Tata Steel to award Reinhausen (Thailand) Ltd. contracts for two further projects in 2021 and 2022.