Seimens USA: Power Factor Increases from 0.2 to 1.0 on Ulbrich’s 5Z Rolling Mill
Advanced motors and drives replace old equipment, with estimated total cost of upgrade being recouped in less than two years of energy-savings alone, thanks to regenerative drive technology from Siemens.
Most coil steel companies spend considerable time repairing and replacing their line equipment, owing to all the factors one would expect in the heavy-duty world of coil processing. The shear weight of the coils, often up to 40 tons, puts tremendous strain on the motors, drives and control components found all along the line. These issues result in considerable wear on the components, substantial cost to the processor for maintenance, and enormous investments in energy costs.
Those days are gone
A new generation of energy-efficient motors, drives and other components, coupled with the emerging concept of the active line module in the drive, allow the regenerative energy strategy to occur. Processors worldwide are realizing substantial savings in every aspect of their maintenance and repair operations (MRO). Ulbrich Stainless Steels & Special Metals, Inc. is a major global supplier of over 140 grades of stainless steel and other alloys. The company is a re-roller and distributor of stainless steel strip, special metals strip, foil, shaped wire, fine wire, sheet, plate, bar and photovoltaic (PV) ribbon product. Ulbrich operates twelve plants in five countries serving North America, Europe and Asia, with additional sales representation worldwide.
Their value proposition centers on exceptional repeatability and reliable physical properties, coupled with a high degree of customized product available with fast turn times. Based in Wallingford, Conn., where the founder Fred Ulbrich Sr. started the business in 1924, Ulbrich quickly became “the biggest little mill in the country,” as the company’s mantra goes. Now over 90 years in business and owned by the fourth generation of the family, the company produces products in various forms and with special coatings, lubricants, adhesives and paints for coding, sound damping and decorative trim applications. Ulbrich focuses its marketing in the automotive, aerospace, medical instruments, cutlery, solar and electronics manufacturing industries, where many of its products, including superfine foils to 0.0004” thicknesses, have applications.
Retrofit decision made
Recently, at the main facility in Connecticut, the decision was made to retrofit a classic Sendzimir 5Z rolling mill with Siemens variable frequency drives and Profinet. As Ulbrich engineering manager Jim Tower explains, “We coupled the desire for the routine retrofit with something we discovered in our research for the project. Namely, the application of regenerative energy in the drives had very high appeal to us, for a variety of reasons.” As Tower explained, the regenerative energy principle would allow power during idle or rollback operations to be redirected to other powered components on the line or back to the electrical grid. The selection of Sinamics S120 drives with Active Line Modules made this development a practical and especially a cost-effective alternative, as Ulbrich and the supplier ran an energy profile on the application. They determined a payback period for the entire line upgrade of less than two years, in energy cost savings alone. Coupled with the reduced maintenance costs and overall improvement in line efficiency, the decision “was relatively easy for us,” according to Tower.
Further reduction in operating and maintenance costs were determined, as the new AC motor and drives technology were replacing old, and in some cases, obsolete methods. As the real-time power load chart shows, the power savings realized were substantial, plus the active front end technology on the regenerative drives resulted in a significant flattening of the usage, thereby putting less stress on the mechanical components of the system overall. The 4Z rolling mill shown in the chart is currently under assessment for a similar retrofit and, according to Tower, that project will likely begin soon. Best of all, the power factor increased from 0.2 to 1.0 on this application, according to Tower, who commented, “We worked closely with Nathan Murray, the drives and motion control expert from Siemens, plus our local distributor, Dittman & Greer (Middletown, Conn.) to effect this changeover and the results were very satisfactory, as we achieved all the targets we wanted, plus got the added benefits of the active line module in the Sinamics drive, which gave us the optimum performance and regenerative energy feature.”