New Controller Cuts Scrap-Handling Costs With Longer Equipment Life And Higher Duty-Cycles For Lifting Magnet Systems

Hubbell Industrial Controls has introduced a new DC generator-based magnet controller that protects against magnet system power spikes; virtually eliminates controller maintenance and premature failures of generators and lifting magnets.

ARCHDALE, NC After more than a year of field testing, a new magnet controller manufactured by Hubbell Industrial Controls has demonstrated that it will vastly reduce maintenance demands while enabling maximum efficiency and control during operation, even in high duty-cycle lifting applications.

By controlling the power to the generator output, the e-mag controller also allows greater flexibility in matching the magnet to the material it is handling.

Hubbell announced the new controller as ready for market in co-operation with its originators, Control Services of Westmont, IL. Hubbell will manufacture the patent pending e-mag controller. Winkle Industries, Hubbell’s master distributor, will market the e-mag controller for use on all makes and models of mobile cranes in recycling and steel mill material handling applications.

Control Services’ John Samila explains that the e-mag DC generator controller takes a dramatically new approach to controlling all power fluctuations inherent in the duty cycles and demands of lifting magnet applications. “The current generation of solid state DC magnet controllers are static controlled devices that are subject to speed and load variations that may negatively impact the magnet system efficiency”.   

These systems are generally outmatched by the job, absorbing massive voltage spikes through very sudden surges and drop-offs. “Our e-mag controller withstands and eliminates inherent magnet system problems by controlling the source which is the generator,” continues Samila.

Instead of reacting to magnet system failures as other units do, the e-mag controls the flow coming out of the generator before it becomes an issue. In essence, the e-mag prevents failures by protecting the magnet system and controlling the generator output for optimum efficiency.

Generator speed matched to demand for power

Regardless of what they have to move, or even with CUT leads the e-mag controller withstands and eliminates inherent magnet system problems by controlling the source of the voltage, which is the generator.

According to Samila, the e-mag controller is designed with a closed-loop circuit that responds to the generator’s demand for power and matches the output to the demand. All other DC generator controllers do not have these dynamic features and therefore, do not have feedback mechanisms to adjust power output to the demand requirements. The e-mag controller de-energizes the generator output when the magnet is not in use. As a result, there’s no failure due to a power spike when the crane operator releases the load.

“Every magnet owner has seen the worst-case for magnet systems,” Samila says. “The generator is running full power to the magnet, the magnet goes into the pile and the output cables get cut causing catastrophic failures on other types of controllers and magnet systems; with the new e-mag, cutting a lead will not damage the controller, the magnet or the generator. 

Typically, DC crane generators are operated at a constant speed (rpm’s) to obtain a constant voltage. Samila says “DC generators are proven reliable in high duty cycle operations whereas AC integrated units come with their own set of issues when combined with high duty cycle applications.  When using an AC integrated magnet system, there are inherent downfalls, not the least of which is a catastrophic failure. That would require removal of the entire system for repair and may require a total system replacement.  The e-mag eliminates that issue and has very few components. It is easily maintained on-site by the customer.    

The e-mag design is ideal for high demand operations and is available for generators from 5 kW to as much 50 kW, with no fear of problems with maximum voltages.

Drop-ball application drove innovation

As America’s largest producer of magnet controllers, Hubbell is very familiar with magnet systems and the problems that inherently arise. Steve Loeck, Hubbell’s Vice President of Sales, reports that the need for a new solution became clear when a customer was attempting to commission a magnet system for a drop-ball application. “This was an incredibly rigorous application,” he recalls. “The drop-ball application required a near 100% duty cycle. The customer was attempting to operate the generator at the required1800 rpm’s and 230 volts, but the on/off cycling of the application requirements caused erratic rpm spikes in the generator that effectively raised the voltage of the generator above 300 volts or more. The existing open loop magnet controller was not up to handling the spikes and the variations in generator rpm’s during the loading and unloading process. With the e-mag, the generator loading and unloading voltage spikes are effectively removed and are no longer an issue. The e-mag controls the generator output, and as a result, when power is not required, the generator is no longer producing voltage. Therefore the generator is not affected by spikes and has a much more efficient cooling cycle.  No voltage; no spike!”

Often, traditional controllers also rely on the crane’s compensation valve to shield them from the impact of sudden surges and drops in hydraulic pressures. Again, the e?mag controller is unaffected by hydraulic loads. Fluids can always flow freely, even in cranes that aren’t equipped with a compensation valve.

Fine tuning the magnet to material

By controlling the power to the generator output, the e?mag controller also allows greater flexibility in matching the magnet to the material it is handling. The e?mag enables infinite voltage control within the speed requirements of the generator. Power can be increased to the maximum for short periods without damaging the magnet. Operators have equal control over the magnet’s draw?down time. For heavily saturated loads such as steel slabs, the release time can be increased to as much as 14 seconds. The maximum draw-down with any other controller is typically about 2.5 seconds.

With this added control, operators can easily set up their magnet system to pick up more material in less time, and release it more efficiently. Combined with a high duty cycle magnet, the result can be significantly more cycles which leads to more material being moved in every working shift.

SMS Mill Services mounts their e-mag controller neatly in a number of locations, depending upon the machine.

Maintenance-free for 15 months

Units were installed on four Liebherr 954 material handlers at SMS Mill Services in Indiana in December 2008. There, SMS owner Rick Gertler reports that all four cranes are in a 24/7 operation, equipped with 72” and 78 “ magnets powered by (25 or 30 kW) generators. Gertler is more than pleased with the results. “We have had zero downtime with these units. By that I mean that, over the past 15 months, we have had no service or repairs to the controller, no servicing for the magnets, no problems with the generators. As one of our long-time maintenance hands said, “I’ve never found a maintenance-free system like this.’ I’m pretty sure we’re stretching the life of our generators, too.”

The four cranes handle a varied mix of material: steel slabs, billets, bushelings, bales, slag. Gertler reports that, with the e-mag controller, the magnets are moving their loads faster and more efficiently. Each magnet is fitted with a scale to ensure accuracy of the material going into the customer’s melt mix. Gertler says the cranes have no trouble lifting their loads, with no bogging down on the pick and no material falling off through the carry. “With the old controllers,” he says, “we would just run out of generator. Now we can run right up to the material and pick the load easily.”

Gertler is convinced enough that he plans to include the e-mag controllers in future upgrades to the rest of his crane fleet in Burnham, IL. “It’s simpler. In this work, simpler is what you need.”

Easy installation, lower cost operation

Joe Schatz, President of Winkle Industries, also expects to see e?mag controllers taking a prominent place in his future business with mobile crane customers. “These controllers will start saving our customers money before they even start to operate. They are very quick to install with no external relays and field resistors required. Because it’s controlling the DC generator, there’s no need to rectify the power to the magnet – so there’s no alternator to install or service. Those four units at SMS Mill Services were installed in 16 hours total – just 4 hours each. Installing a conventional controller easily takes a 9 hour day each, with two technicians on the job. The whole system is surprisingly simple. The e-mag makes setup and troubleshooting dead easy, too. Everything is easily accessible. If there’s an issue, you’ll know right where to look. And in the long run, with no spiking or overheating, our magnets are going to stay in service much longer, too. Heat is the worst enemy of magnet coils and generators. Customers will really get the most service-life and most productivity out of all the equipment in their magnet systems with the use of the e-mag. It’s a very cool concept, in more ways than one!”

Schatz believes that, by improving the control of the system’s power profile, e?mag controllers will allow cranes to use smaller generators to power their magnets. “You’re able to run up the voltage for short periods to get extra power out of the generator when you need it. But then the generator gets a chance to cool off through the release cycle whereas, other controllers don’t give you this flexibility.”

“You’ll see customers getting longer life from their generator, moving more material and spending less on fuel for the job!”

Contact:

 Steve Loeck
Vice President of Sales
Hubbell Industrial Controls, Inc.
4301 Cheyenne Drive
Archdale, NC  27263
SLoeck@hubbell-gleason.com
Tel: 336-434-2800   Fax: 336-434-2801

Winkle Industries Inc.
Mark Volansky, Sales Director
2080 West Main Street
Alliance, OH  44601
sales@winkleindustries.com
Tel: 330-823-9730   Fax: 330-823-9788