Powering production in food plants is not as simple as throwing a switch. Peak-time charges, outages, surges and other factors can complicate calculations of cost and reliability and require solutions that go beyond standardizing on premium motors.
The good news is that OEMs are delivering solutions on multiple fronts, from systems approaches to power delivery and servo options to sanitary design improvements and smart motors.
Maintenance is leaping from Internet of Things hype to shop-floor predictive maintenance with a condition monitoring device from ABB Inc. (www.abb.com). Called the Ability Smart Sensor, the device is priced in the low three figures and monitors vibration, current and temperature to assess bearing condition, operating temperature, air gap eccentricity and rotor winding health.
Initially, food maintenance technicians can check the health of motors through a smart phone app; in April users will be able to upload data to a cloud server for trending and other analytics, according to Kyle Davis, smart sensor technical support engineer in ABB’s Greenville, S.C. facility. “With the Internet of Things (IoT), new features like percent loading can be added with a firmware release.”
Slightly larger than a deck of cards, the sensor is attached to a motor’s fins with a two-part epoxy. The unit is motor agnostic, though it will be factory fitted to severe duty NEMA motors manufactured by ABB’s Baldor Reliant division when availability catches up with demand.
Compatible with motors up to a NEMA 449 frame, the diagnostic tool is specific to the motor it is attached to, Davis explains. End-users register the sensor’s serial number and the motor’s load bearing size, frequency and other specifications to generate diagnostics specific to it.
A traffic light display of green, yellow and red lights provides an at-a-glance assessment of the motors in a facility. A numeric score also is delivered. “Anything over six is an alert,” with service recommended at the next opportunity, he says. “Over 10 is critical.”
Thousands of the smart sensors already are deployed in Europe. U.S. installations were delayed until UL certification was secured. Based on early results, end-users are realizing a 70 percent reduction in downtime.
“It’s that extra tool in your bag and your first line of defense to assess condition and move you to predictive maintenance,” Davis concludes.
Energy consumption also is reduced, though given the power loss that occurs when rotating motion is converted by a gear or drive, a system’s approach is needed for optimal performance. SEW Eurodrive demonstrated that truth with Movigear, the mechatronic drive system that combines motor, drive and inverter.
The concept is coming to drum motors in the second quarter when Toronto-based Van der Graaf Inc. (www.vandergraaf.com) commences production of its integrated DFI frequency inverter within a drum that includes the motor and drive. Owner Alex Kanaris calculates the energy savings at 70 percent.
Drum motors have a 30-year track record of powering conveyor belts, though reliability issues and food-waste accumulation kept them out of many food-production environments, particularly meat and poultry. Kanaris credits his firm’s work in the mining industry with helping it resolve the reliability issue. Sanitary design led to improvements like a 316 stainless steel drum with motor, gear drive and all moving components enclosed. Compared to a conventional drum with an external drive and no permanent magnet, the system produces about a 25 percent energy savings.
“It’s a three-phase motor with an electromagnetic field in the rotor that boosts the stator,” he says of the assembly. The addition of a digital frequency inverter enables speed control with an IoT connection. The drum assembly comes with its own IP address, though it also can be controlled through a local network.
Incorporating the frequency inverter into the assembly increases the importance of the motor encapsulation process that Van der Graaf calls vacuum pressure impregnation. Epoxy typically is added to the motor cavity to encapsulate wiring and harden the windings to prevent premature failure. Any air pockets in the epoxy can pick up a charge from static electricity and destroy the motor when it discharges.
To eliminate voids, Van der Graaf submerges the motor in varnish and applies vacuum during a one-hour process. “You end up with almost zero air pockets,” says Kanaris. This step, along with synthetic lubricant in a gearbox that is closed to atmosphere and not prone to oxidation, gives the firm confidence in guaranteeing 50,000 hours of run time between oil changes.
Servo and induction options
Interroll Corp. (www.interroll.us), Wilmington, N.C., also supplies sanitary drum motors. According to Steven Olszanowski, product engineer-drum motors, the OEM will replace its synchronous motors with steel gearboxes with drums powered by either an asynchronous induction motor or a synchronous motor with a permanent magnet.
Interroll introduced a synchronous servo motor seven years ago, installing it in slicing machines as well as drums. The asynchronous option extends the application possibilities.
Servo drives are old hat for Kollmorgen (www.kollmorgen.com), though the Radford, Va., OEM also supplies AC induction motors. Regardless of what type of motor is used, difficulties in cleaning and the existence of areas that can serve as water receptacles were the top two motor complaints in a survey commissioned by Kollmorgen and conducted by the Virginia Tech Food Science and Technology Dept., according to Bill Sutton, market development manager.
Those findings led to a redesign of the company’s AKM servo motors, which carry an IP65 or IP67 rating, neither of which is sufficient for high-pressure washdown with caustic chemicals. The result is the AKMH, short for advanced Kollmorgen motor hygienic.
In a comparison test with the AKM and a competitor’s motor, surfaces were inoculated with a nonpathogenic strain of E. coli in three areas: labels and surface finish, seals and fasteners and cabling. While microbes were detected post-washing on the other two motors, no bacteria was detected on the AKMH, which was designed to meet the 10 sanitary design principles established by the American Meat Institute.
The use of 316 stainless steel with a 32-micron surface finish helped achieve that result, Sutton says, along with a cable connection that uses a bushing interface instead of a more typical metal-to-metal interface.
Picker machines that remove the feathers from chickens after slaughter pose one of the harshest work environments for motors, suggests Donald Stier, marketing manager at SEW-Eurodrive Inc. (www.seweurodrive.com), Lyman, S.C. Typically, those motors last two months, and each machine can have a dozen or more motors, making machine downtime virtually unavoidable. After SEW installed a unit with a food-production option of specialized components in a picker, the motor-and-gear combination ran for four-plus months.
A fully encapsulated stator and conduit box and an IP69K stainless steel power connector are part of the added protection, along with PTFE seals and a keyless hollow shaft bushing system.
Nord Gear Corp. (www.nord.com), Waunakee, Wis., is a direct competitor of SEW. Nord engineers have focused on manufacturing standard reducers with the corrosion-resistance of stainless steel without the high cost. The result is Toph-2, an electrically catalyzed process in which the aluminum housing is bathed in an alloy that provides a hard, rough surface that permanently bonds to the substrate. The housing resists corrosion, is less expensive than stainless steel and allows the motor to run much cooler, extending service life.
Nidec Motor Corp. (www.nidec.com) boasts one of the largest portfolios of motors, drives and gears, though the St. Louis-based division of a Japanese OEM is far from a household name. U.S. Motors, formerly the fractional motor division of Emerson, is Nidec’s best-known North American brand. Nidec’s other acquisitions include three divisions that make right angle gears, points out Tim Albers, director-product management. Everything from micro-watt motors to 10,000 hp units are manufactured.
A recent addition to the portfolio is Forecyte, a battery-powered wireless sensor for condition monitoring of rotating equipment. Unlike the ABB sensor, it doesn’t monitor current, but it does measure vibration and temperature. It also lacks some of ABB’s features, Albers allows, but is a useful diagnostic tool for compressors, pumps and other equipment.
“There has been a lot of talk for a long time about IoT, but now the infrastructure actually exists,” he notes. Instead of investing six figures to create a foundation for a system with uncertain ROI, tools like Forecyte are giving manufacturers the opportunity to “dabble in it for $10,000-$15,000,” he adds.
Baldor Reliance debuted its expanded and upgraded line of Food Safe motors at January’s IPPE Expo. “The real sweet spot for stainless steel motors is up to 5 hp, but we get a lot of customer requests for larger and larger ones,” explains David Steen, product manager-definite purpose motors at the Fort Smith, Ark., manufacturer (www.baldor.com). The line now ranges from 0.5-30 hp.
Cast stainless steel feet replace sheet metal feet, and a “perfectly round” conduit box sealed with an O-ring eliminates any possibility of water pooling. Crevices and contours that might collect water also were smoothed out, according to Steen.
Prior generation stainless steel encapsulated motors also were IP69K rated for water, “but we’ve improved some of the sealing,” he adds.
Higher IP ratings are more rule than exception for motor manufacturers as they tighten construction to extend life in harsh washdown environments. Condition monitoring is poised to become a common feature, once sensor costs decline even further. And integration of controls with motor and drive components promises to reduce reactive power loss to levels thought impossible in the not so distant past.