Centralized or Decentralized?

Dr. Arne Linder, Product Management at Kollmorgan's Ratingen (D) plant considers which architecture type delivers the best technical and commercial advantages ?

Dr. Arne Linder

Decentralising servo technology can bring machine and plant construction savings during installation. Two additional advantages include reduced cabinet heat loads and more straight forward drive architecture. The question arises however, which technology is better, an integrated motor/drive solution or a detached motor and drive?

So often in life the answer to a question is neither A or B, but instead C. This is true for the discussion of decentralized versus centralized servo technology in determining the best system. What architecture is best from a commercial and technical standpoint for a particular application? Instead of A or B, the answer C comes about through mixed architectures, a coexistence of both types. In this case the two approaches can be easily combined when the drives have a large number of common features. As such, standardization of these platforms is the best approach.

Space-saving drive solutions with a modular design are required for machines in the food and packaging industries. Distributed servo technology supports this trend.

The centralized architecture
In contrast to horizontal conveying where decentralized servo drives are a common sight, centrally located servo drives are still dominate the market for highly dynamic and precise motion control. Servo drives along with other control components, sometimes with a full blown IPC, reside together in a control cabinet protected from the outside world. Connection to the motors is in a star shaped structure, each having control and power cables. Because heat loss is centrally generated, effective air conditioning is needed in the cabinet.

The decentralized alternative
Decentralized servo technology follows the basic principal of shifting the individual motor control from the central control cabinet to be closely located to the process This architecture makes necessary a robust design providing a high degree of environmental protection. The advantage lies particularly in terms of motor cabling. Two other advantages are improved EMC-behavior and the widespread distribution of heat loss, reducing the cost or need for a centralized cabinet climate control system.

Trends in machine building industry
Especially with packaging machinery and machines for the food and beverage industry, the trend is away from meter long cabinet walls but instead installing small, highly self-protected units within the machine frame. The progressive trend is toward modularization of production facilities making necessary the distribution or combination of functions. This statement is reinforced by the fact that production equipment consist of a main process and ancillary tasks. The latter are a variety of compatible modules – for example conveyor systems, sorters and handling units. This provides a path for easy expansion of the machine. Against this backdrop, practical experience shows that a decentralized structure is advantageous, especially with spatially distributed single axes. In contrast, machine modules for synchronized axis physically close together and centrally located drives in a cabinet are generally considered the preferred structure.

The layout is a distributed servo drive architecture
 with AKD-N servo drives, different motor types,
and single-cable connection technology.

Monetary savings in installation and mounting
The savings potential of decentralized technology can be clearly shown based on a real metal forming machine having eight axes. The first axis of which is located 5 meters away from the control cabinet with each additional axis located 3 meters further. A centralized control system would be characterized by a central control cabinet housing the drives with each motor having separate shielded power and feedback cables adding up to 248 meters of cable.

Specifically designed the distributed servo drives
for the AKD-N range as distributed devices,
so that there are no deductions in power density.

Instead, a combination of a single KOLLMORGEN AKD-C power supply module and 8 decentralized AKD-N servo controllers would reduce the cable requirement to 34 meters. The calculation: A single 5 meter hybrid cable supplying power and field bus for axis control is connected between the power supply module and the first decentralized controller. A single hybrid cable 3 meters long connects each additional drive for a total of 21 meters. Because we assume that each motor is located 1 meter away from each decentralized AKD-N drive KOLLMORGEN provides a one-cable motor connection technology, only 8 additional meters of cable is required. Overall, the decentralized system reduced the cable requirements from 248 to 34 meters, a savings of 86 percent. These figures represent an idea of the overall monetary gains for the OEM including cable costs and reduction in assembly effort. When the axes require additional I/O the reduction in cabling is even more obvious. Instead of 372 meters, only 42 meters is needed, a corresponding saving of 89 percent.

Another benefit of the relocation of drives is the reduction of power dissipated in the control cabinet. This effectively reduces the requirements for air conditioning thus providing direct saving for both the OEM and end user. As such, the control cabinet air conditioner can be reduced in size or completely eliminated, reducing costs for hardware and subsequent operation ultimately increasing energy efficiency.

Technical advantages by decreasing complexity
The AKD -N series KOLLMORGEN drives provide IP67 protection and connection via an eleven millimeter diameter hybrid cable to the central supply module in the control cabinet. This single cable provides power and communications without the need for any additional cabling. Each AKD –C supply module can support two strings of AKD -N drives up to 4 kW each, and up to 8 AKD –N drives per string. Safe Torque Off shutdown performed via the hybrid cable comes as standard, and can be implemented for each drive individually or as group. Also, only one cable is necessary between the distributed servo controller and its connected motor thanks to a new single-cable technology. Two cables are no longer required to provide motor power and feedback. In material handling applications where precise motion is demanded, separate cable trays or tow chains are often required for motor and feedback cables. This requirement is now reduced because there is much less cabling.

Winning with increased design freedom
Sample calculations show that the decentralized servo technology saves space in combination with the single-cable connection technology between motor and controller. This benefit results in smaller cable trays, lighter drag chains, and more compactness giving more design freedom in the development of new machines. This freedom resulted primarily from the fact that the distributed technology extends modularization capabilities in comparison to the unflexible, central control design. The bottom line is that this allows new OEM plants to create new machines from already developed modules making the engineering more efficient.

More order in the tangle of cables: If servo drives are used right next to motors, the elaborate power wiring from a central control cabinet can be dispensed with. Installation becomes clearer.

Distributed drive technology as a hybrid
A second way to decentralize is with the use of a hybrid integrated solution. These are combined motor and servo controller units without the need for external wiring. This so-called “piggyback” solution has the disadvantage of drive derating with increased ambient temperature. The higher the ambient the more performance reduction occurs in order for the drive to self-protect from overheating. This relationship ensures in practice that the motors must be larger than otherwise necessary to give the required performance within acceptable temperature limits for the electronics. Typical servo tasks such as rapid acceleration and deceleration during positioning can be especially difficult in the design of hybrid solutions due to the problem of effectively dissipating heat.

However, separating the motor and drive at this point prevents the inherent design-related derating. This solution provides the basis for smaller motors in combination with better energy efficiency. In addition, integrated combinations are usually focused on a single motor type, limiting flexibility in the machine design. In contrast, any KOLLMORGEN brushless motor type can be connected to the decentralized AKD-N servo drive. These motors include conventional or direct drive rotary and linear direct drive types, providing true design freedom and optimum performance.

An integration example
In conclusion, to clarify these relationships an example of servo drive technology for a food processing machine will be shown. The process begins with the cutting of sausage and cheese by a so-called slicer. The product is conveyed onto a belt. The process is not just a simple matter of conveying a sausage stack from point A to B but to transport it as well defined shingles. The need for highly dynamic single axis positioning system is clear. The question now arises how to integrate the required sophisticated motion control functions while maintaining centralized machine control. The slicer provides a good example because it represents a specific decentralized axis because its high power requirement cannot be met with a decentralized drive. The primary objective from the manufacturing perspective is to harmonize highly diverse functional requirements for a wide combination of centralized and decentralized solutions. The KOLLMORGEN AKD-N drive deliberately focuses on the use of a centralized AKD platform. It provides appropriate technology to allow the optimum selection of a motion solution for the performance task required, offered through the wide variety of compatible actuators.

PLC support helps pump OEM create application-specific water pressure boosting systems.

The easy configurability of ABB's AC500 PLC range is helping the specialist pump OEM, Plad Equipment, to rapidly produce application-specific pump systems for boosting water pressure in high-rise buildings.

Plad's dual- and triple-pump systems are widely used for pressure boosting. However, virtually every application in the buildings market demands a degree of customization, both operationally, and in form factor - to fit into the spaces available and interface to pre-determined inlet and outlet piping. To simplify the operational configuration of pump control, Plad decided to standardize on ABB PLC control for water pressure boosting systems.

Before the switch, Plad had used ABB drives for a long time, but tended to buy its PLCs from different suppliers, and to integrate the control system in house. This multi-supplier approach had led to the occasional system integration problem in the past. So, when ABB approached Plad to talk about its ongoing development of a new modular 'water library' of PLC software - which features a large range of relevant pump control and data collection functions - Plad became interested.

ABB proposed a new pump control solution based on the continued use of ABB's ACS550 variable speed drives, but with control provided by the AC500 PLC. To demonstrate the effectiveness of the drive and PLC combination, ABB developed a flexible control program, which utilized many pump control functions from the development version of its Water Library software.

It was clear to the OEM that this proposed solution offered a great deal of flexibility, allowing Plad to configure one master software package for dual or triple pump systems, as well as select other operational parameters required for different types of high-rise building water pressure boosting.

ABB's example design also provided a number of technical advances over Plad's own previous control system arrangements. The use of Modbus RTU networking eliminated equipment cabling and simplified system assembly. The ABB PLC’s high level Function Block library for communications also simplified data exchange with the ABB drives, speeding control development and simplifying maintenance tasks on Plad systems.

The proposed control solution, combined with ABB's obvious willingness to provide in-depth support on control matters, proved very attractive for Plad. So, Plad made the switch and now specifies ABB PLC and drive systems for all of its pumping systems for the building market.

"We are pumping specialists first," says Robert Delisle, director of Plad Equipment, "so, standardization on a single control systems supplier makes a lot of sense. It means that we sidestep any potential system integration problems. However, the key deciding factor in choosing ABB as our supplier was its willingness to act as a technical partner and provide in-depth support. If a user needs new functionality we can always call on ABB experts to discuss or help us implement a change. This partnership becomes very attractive for a mid-sized OEM like us - allowing us to focus most of our technical resources on our core pumping technology and applications know-how - and I believe it will help us to expand our business."

"Having a strong relationship with a customer makes it easy for us to invest our own time - to ensure that our products are used in the most efficient way, and to use our control systems expertise to help clients meet new challenges," adds Patrice Bélec, a PLC Product Specialist with ABB Canada.

The pumping systems that are used for water pressure boosting in high rise buildings can be configured in many different ways depending on factors including the water pressure available, the size of the building, the spaces available for risers and equipment such as valves and break tanks on higher floor levels. To deal with this complexity and match the solution to the application, Plad offers a broad range of pumping systems with many configuration choices such as the ability to have dual or triple pumps to meet varying demand levels and for reliability, variable speed operation, local or remote instrumentation. Systems are also typically assembled on small skids, which allow a great deal of flexibility over the size and shape of the finished system. The pumping action required from each system can also vary greatly in complexity depending on the application and the needs of the user, and custom-made control panels are fitted to almost every system shipped.

The combination of the proven ACS550 drives and AC500 PLC in this application add - on top of energy efficient operation - flexibility and connectivity to Plad's pump product lines. This facilitates simple maintainability and ensures that future requirements can be incorporated with minimal engineering efforts by a PLC engineer. The AC500 also acts as the central interface for several pumps or ACS550 drives to the system's CP600 HMI panel, enabling open interaction, monitoring and visualization of single pumps, as well as the whole pump-set configuration.

Hygrometer approved for explosive atmospheres in Brazil!

Michell Instruments’ MDM300 I.S. high-speed portable dew-point hygrometer has gained certification from INMETRO, the Brazilian National Institute of Metrology, Standardization and Industrial Quality for use in hazardous or explosive atmospheres. The MDM300 I.S. already carries certification from ATEX, IECEx, CSA, FM and GOST. The Brazilian certification extends the instruments’ global coverage. With its custom-designed sampling kit, the MDM300 I.S. is able to make reliable measurements in natural gas streams at up to 350 bar, giving readings that are representative of actual process conditions. Because it is a portable instrument, the MDM300 I.S. enables measurements to be made at multiple points in the process – which means that points of moisture ingress are identified quickly and easily before damage is caused. Michell’s thermo-paramagnetic oxygen analyzer, the XTP601 and explosion-proof dew-point transmitter, the Easidew PRO XP, also have INMETRO Certification. • Michell products are marketed in Ireland by Instrument Technology.

T & M powersources for USA and Europe!

Interpro Systems have been appointed by Preen, specialist manufacturers of test and measurement power Sources as their distributor for the USA and Europe. These new product lines complement and widen INTEPRO’s existing portfolio and will deliver new business with established customers as well as taking INTEPRO into the new, fast-growing, Green energy industries.   

Established in 1989 Preen have become a major manufacturer of AC and DC Power Sources and Frequency Converters and is one of only three manufactures of “Regenerative” AC Power Sources. Preen is considered to be the world leading manufacturer of large capacity power sources as used by Green Energy equipment suppliers.

With its headquarters in Taiwan, Preen produces 65MW of AC power products per year and has three factories with 370 employees, including an R&D team of 55 engineers. In addition to supplying a large number of global OEMs Preen has provided Grid simulators and Voltage regulator sources to most international EMC certification labs where clean controllable energy is key to their customers operation.

Preen are at the leading edge of renewable energy and electric vehicle development and test as well as the more traditional markets of test and burn-in of industrial and military systems, IT, automotive, medical and white goods. The Preen product range provides complete solutions to customer’s power requirements and includes Linear Transistor AC power sources from 0.5 to kVA, Industrial AC power sources operating at 47~63Hz rated from 0.5 to 2000kVA, Military 400Hz AC power sources from 0.5 to 400kVA, 45~500Hz Wide Frequency power sources from 0.5 to 300kVA, Shore Frequency Converters from 300 to 1200A and Grid Simulation power supplies from 6 to 2000kVA.

The new, very comprehensive Preen product range is supplied at a very competitive rate, maximizing performance on the tightest of budgets.

Preen offer a full range of services to customers including on-site planning and technical consultancy, full engineering installation service and an upgrade support in the event of a regulation change.

Stuart Gibson, Interpro's Sales Manager comments, “Preen is an experienced, customer proven supplier of high efficiency power solutions for test and measurement applications in industrial and new energy markets and is an excellent fit alongside our own power test and electronic load products.”

New addition to sales management team in USA!

The leading provider of high-precision micro-assembly equipment and customized electronics manufacturing solutions AMICRA Microtechnologies GmbH, has selected Joe Ettipio as Sales Manager for the U.S. Western Region. Mr. Ettipio will be responsible for the company's state-of-the-art portfolio of die bonder and flip-chip bonder systems, wafer inking systems, dispense and test systems, and other advanced technology solutions and services, working out of his home office in California.

Joe Ettipio

He is the second addition to the U.S. Sales management team this year, and will be responsible specifically for the Western region of the United States. Joe brings along with him 24 years of diverse experience as a technical sales professional, selling and working in the front and backend microelectronics and semiconductor industry, as well as medical and aerospace and defense facilities, predominately located throughout North America and Europe.

He received a Bachelor of Science degree in Electrical Engineering from the State University of New York at Buffalo. He got his start into the field as an Electrical Design Engineer for General Dynamics in San Diego, California, which was then followed with him holding Sales Manager positions at Orthodyne Electronics, covering the European community, and Palomar Technologies, specializing in the Western U.S. Through these sales management experiences, Joe has established a proven track-record of creating and optimizing business relationships and markets, successfully managing projects throughout all phases, and maximizing sales results.

Since then, Joe has held several high-ranking leadership positions including being President of JPE Sales, Inc., Director of Sales (Americas) for F&K Delvotec, as well as serving the past 4 years as Director of Sales & Business Development (Worldwide) for McBain Systems.

From these positions he has solidified expertise in the area of die attach, wire bonding, inspection and measurement solutions as well as equipment customization to fit technically challenging niche applications requiring specialized optics, high accuracy motion control, automation and more. All of Ettipio’s experiences have given him an understanding on how to define and deliver solutions for complex customer requirements, and a dedication to boost customer satisfaction by meticulously managing projects from inception through installation and follow up.

Preconfigured A/D XMC Modules for radar, communications & data acquisition applications!

The newest members of Pentek's highly popular Onyx® family of high-speed data converter XMC FPGA modules: the 3-channel Onyx Model 71721 and the 4-channel Onyx Model 71761, 200 MHz 16-bit A/D XMC modules based on the high density Xilinx Virtex-7 FPGA. Each has a programmable digital down converter and a suite of built-in programmable cores.

“These modules hit the current sweet spot for performance and functionality with their built-in IP cores that eliminate costly development effort," said Bob Sgandurra, Pentek’s director of Product Management. "The increased space for IP in the Virtex-7 also leaves plenty of additional room for customer supplied applications."

A/D Converter Stage

Each module has a front end A/D converter stage that accepts three (Model 71721) or four (Model 71761) analog HF or IF inputs on front panel SSMC connectors, with each transformer-coupled to Texas Instruments ADS5485 200 MHz, 16-bit A/D converters. The 200 MHz sampling rate handles the needed bandwidth for a wide range of signal processing applications. The Model 71721 also includes a two-channel 16-bit 800 MHz D/A converter.

Performance IP Cores

The Model 71721 and Model 71761 come preconfigured with a suite of built-in functions for digital down conversion, data capture, synchronization, time tagging, and formatting, making them ideal turn-key interfaces for radar, communications, or general data acquisition applications. An A/D acquisition IP module is included for easy data capture and delivery to system memory.

The Model 71721 and 71761 each feature a complete beamforming subsystem. The DDC core contains programmable I & Q phase and gain adjustments followed by a power meter that continuously measures the individual average power output. The time constant of the averaging interval for each meter is programmable up to 8K samples. The power meters present average power measurements for each DDC core output in easy-to-read registers. A threshold detector automatically sends an interrupt to the processor if the average power level of any DDC core falls below or exceeds a programmable threshold.

A programmable summation block sums any of the four DDC core outputs, with a power meter, threshold detector and a programmable gain stage to compensate for bit growth. The sum can be selected for output across PCIe. Alternatively, for larger systems, local sums from several boards can be aggregated via a built-in Xilinx Aurora gigabit serial interface, daisy- chained through the P16 XMC connectors.

The Model xx721 also includes a waveform generation IP core and a programmable interpolation filter to support digital upconversion within the D/A.

Boosting Performance with the Onyx Architecture

Building upon the proven design in the Cobalt Virtex-6 family, architectural enhancements in the Onyx family include a doubling of the DDR3 memory in both size and speed to 4 GB and 1600 MHz, respectively. The PCIe interface has been upgraded to Gen 3, delivering peak transfer rates up to 8 GB/sec. The Virtex-7 is more power efficient than previous generations making it easier to utilize larger FPGAs. Optional LVDS and gigabit serial connections to the Virtex-7 are available for connecting to custom high performance I/O.

Development Tools and Software Support

GateXpress® PCIe Configuration Manager is a sophisticated FPGA-PCIe hardware engine for managing FPGA reconfiguration. At power up, the GateXpress manager immediately presents a PCIe target to the host computer for discovery and enumeration, giving the FPGA time to load from FLASH. Once booted, the GateXpress manager offers multiple options for dynamically reconfiguring the FPGA with a new IP image, handling the hardware negotiation and streamlining the loading task. GateXpress also allows dynamic FPGA reconfiguration though software commands as part of the runtime application.

For systems that require custom functions, IP can be developed using the Pentek GateFlow® FPGA Design Kit, extending or even replacing the factory-installed functions. Software support packages are available for Linux and Windows operating systems.

Form Factors 

The Model 71721 and Model 71761 XMC modules are designed for both rugged and lab environments and are available in CompactPCI (Models 73721 & 73761), AMC (Models 56721 & 56761), PCIe (Models 78721 & 78761) and VPX (Models 53721 & 53761).

Power centre brings BS EN 61439 peace of mind!

Boulting Technology has launched a new range of low voltage (LV) switchboards. The new Boulting Power Centre (BPC) series offers users BS EN 61439 compliance - a mandatory requirement from 1 November 2014.

BS EN 61439 has been developed to simplify and clarify the means by which the performance of applicable products and assemblies, including switchgear, can be verified against the requirements of the standards. It completely replaces BS EN 60439-1, which will be withdrawn on November 1, 2014. 

In the new standard, some established definitions and practices have been radically revised and new methods of verification have been added. Whilst it retains critical safety-related technical performance requirements, the methods by which performance can be verified have variously been extended, simplified and made more accessible.

LV switchboards distribute electricity within a user’s premises. A mains supply from the grid is subdivided to feed electrically powered equipment, allowing disconnection and protection of assets as required.

The BPC range meets the requirement for higher fault ratings typically found in both commercial, including data centres, hospitals and offices, as well as industrial applications.

The range is available in 100kA, 80kA, 50kA and 25kA specifications, each one offering simple integration and high levels of reliability thanks to their innovative design. Busbar ratings for the 100kA unit are 100kA for one second, with current ratings from 6300A to 2500A, and for the 80kA, current ratings from 1600A to 4000A. This allows flexibility with switchboard layout at the initial design stage.

The LV switchboards are naturally ventilated instead of  forced ventilated, providing greater reliability whilst helping to reduce energy costs.  The specially designed heat dissipation system provides inherent reliability ensuring users achieve maximum availability.

Furthermore, this method of ventilation reduces the footprint by ten to twenty per cent, meaning that even the BPC100  model can be implemented without compromising on space. This provides companies with ample space to grow should their need increase, negating costly plant room extensions further down the line. 

"Here at Boulting Technology we offer turnkey solutions as well as custom design, build, installation and commissioning service," explained managing director, Gordon Mullis. "This enables us to deliver designs optimised for maximum cost efficiency without compromising quality or performance.

"In addition to cost and efficiency, we understand that our customers worry about meeting the latest safety standards and so the new LV switchboard range is already compliant to the stringent BS EN 61439 standard, ensuring that companies are meeting the requirement today."

The Boulting Power Centre series utilises the latest range of ABB low voltage switchgear products including the new innovative SACE Emax 2 range of ACBs (Air Circuit Breakers). These are designed to provide intelligent management of power supplies and energy use. This enables power consumption to be reduced, helping businesses to meet energy reduction targets and maximise efficiency.