Timken unit manager Reed Brown Jr, it said, was pleased to report good results following the installation of the technology – now designed and sold by Magentek Material Handling under the brand name OmniPulse.
The Timken Company, which produces bearings, steel and components at its plant in Canton, Ohio, has used direct DC (DDC) digital drives for the last four years. Timken employs the DDC drives to control dual hoist cranes that operate in a pickle line where 10 US ton bundles of tubing are dipped into large acid tanks at approximately 35 lifts per hour.
The OmniPulse DDC digital drive was formerly marketed by Eaton Corporation. In March 2006, Magnetek Material Handling and Eaton entered into an agreement whereby Magnetek now provides sales, support and service of Eaton DDC drives to the crane and hoist industry.
Already one of North America’s leading suppliers of AC crane control systems, Magnetek took over exclusive responsibility for design, manufacturing, sales and service of integrated DDC drive systems incorporating Eaton components.
According to Brown, prior to the installation of the DC digital drive, the dual hoist cranes were controlled by DC Constant Potential (DCCP) control boards that were almost 30 years old and worn out. These controls were failing about once a week – with each failure causing 10 to 15 minutes downtime. Timken wanted to eliminate this downtime and also wanted smoother, more energy-efficient control of its dual hoist cranes.
DDC drives are “a technologically advanced” replacement for the traditional DC electro-mechanical series motor drives used for crane control. Magnetek’s chief DC drives sales and support engineer Bob Borgman explained: “This solid-state DC to DC drive employs high-speed semi-conductors in the microprocessor drive to maximize crane performance and reliability, minimize downtime and maintenance and save on energy costs.”
Borgman added: “The microprocessor in the DDC drive provides smooth acceleration and deceleration, reducing the inrush amounts of current, thus prolonging the life of the motor. The smooth acceleration also controls the impact of the speed changes to other mechanical components, reducing the cost of mechanical repairs,” he concluded.
Designed to withstand harsh mill environments, the drive is retrofitted within the existing space where the DCCP control used to be. It is engineered as a “drop-in” replacement using the same connections.
Brown recalled: “Our first DDC drive was originally programmed to operate in conjunction with the existing contactor board drive for the other hoist. After a trial period, we converted the other three functions on the crane. Since then we have converted two of our cold draw benches, another crane and two 2-roll straighteners.”
Brown continued: “Downtime is reduced due to the elimination of all the speed contactors and also the speed point resistance banks. The only resistance bank you need is for a dynamic braking circuit. Fewer moving parts equals less maintenance and downtime.”
Brown further explained the maintenance savings Timken has realised. He said: “Installation costs for a DDC drive are very similar to a contactor board, but the savings come from reduced energy requirements and maintenance.”
Timken also compared the power consumption of the DDC drives with the company’s former DCCP controls in the field and found the major savings during acceleration and deceleration.
The amount of energy savings depends on the horsepower, the frequency of use, and the acceleration and deceleration rates. The drives have infinite speed points available so they can be fine-tuned to any application. Hoist circuits, like those at Timken, are “good candidates” according to Borgman. In addition to crane and hoist applications, DDC drives also can be employed in quench cars, rolling mills and a variety of other applications.
Brown added: “Our maintenance staff are comfortable with the DDC drives and are constantly looking for new applications. If we need a DC board or drive in an application, we will look at this product first.”
With the installed base of DC Electro-mechanical control reaching the end of its economic life, DDC control systems are expected to displace traditional DC technology in the overhead material handling and industrial process control markets.
Magnetek concluded: “There are some 3,000 active cranes running in North America alone with traditional DC controls that could be retrofitted over time. The advanced technology used in the OmniPulse DDC drive provides a solution to the ever-increasing concerns with rising energy costs and the need for improved performance and reliability.”
