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Electric drives: the road to customisation

13 November 2015

Danfoss recognised early on that its customers wanted customised and application specific products, rather than a standard drive that they needed to adapt. Sara Bernard reports.

The earliest mass produced variable speed drive in production at Danfoss' Gråsten site back in 1968
The earliest mass produced variable speed drive in production at Danfoss' Gråsten site back in 1968

It is a fact that hardly any aspect of daily life can be managed without electric drives. Some 65 to 70 percent of all electrical energy consumed is used to run electric motors, so variable speed drive technology holds a great deal of potential for reducing energy consumption.

The number of variable speed drives (VSDs) installed throughout the industrial world is rising in response to a growing demand for optimised processes and lower production costs, as well as more efficient use of energy.

In the 19th century, it was the invention of the dc motor (1833) and three-phase motor (1889) that brought about significant change to industrial processes. But it wasn’t until 1968 when the first series of mass produced variable speed drives came to market that set in motion a rapid technological evolution. That drive was the first VLT series from Danfoss. Almost 50 years on and the drives market has changed out of all recognition

New millennium, new possibilities
Drives manufacturers realised that the need to reduce energy consumption whilst reducing costs was becoming a top priority for their customers. Remaining innovative and producing variable speed drives that met these requirements was becoming paramount for manufacturers who wanted keep ahead of the field.

At the beginning of the new millennium, research and development experts at Danfoss Drives reasoned that the vast possibilities offered by information technology were enabling more and more features; at the same time, they recognised that the demand for customised and application specific products was on the increase.

In response to these forecasted market conditions and industry trends, Danfoss focused on identifying the separate elements in the architecture of standard drives and the internal communication between them. These individual elements make up the modular approach that the company adopted as the foundation for creating the next generation of drives across its product range - the main objective being to reduce the cost of development and time to market.

That same philosophy underpins the novel supply chain set-up adopted by Danfoss Drives. This modular concept enables the manufacturer to produce drives in high volumes and in numerous variants; to be utilised in a variety of applications in many industrial sectors.

Commensurate with the aims of Industry 4.0, Danfoss has an advanced IT system that controls the assembly of a drive from the moment a customer has defined its specific features.  The specifications given by the customer at design stage determine which printed circuit boards, frames, enclosures, EMC filters, user interface, software, fieldbus and options are to be included in their customised drive.  All requested components are built-in and tested in the factory before shipping.

Indeed, this ‘build to order’ approach means that customised drives can be built and shipped within hours. From a limited amount of choices of each element, thousands of different drives can be configured to meet specific customer requirements. Even the manuals are printed on-demand in the required language and shipped with the drive. This means no stock of finished drives and no stock of possibly outdated manuals.  In 2006 this manufacturing strategy won the Frost & Sullivan Award for Product Innovation.

Modern drives can now be easily combined and fitted to a variety of motors from numerous suppliers (motor independency), enabling users to obtain systems perfectly matched to their needs. They allow users to expand the system at a later date if necessary and make it easier to adapt the drives to a modified plant design or new processes, easily and without major effort or expense.

In recent years, there has been a major trend in the marketplace to move towards increasing intelligence within the drive. Many functions that previously were handled by a central controller are now migrating to the drive, becoming built-in functions in majority of cases.

User-specific adaptations are now possible with freely programmable extensions and EMC measures are now classed as essential by the majority of customers. As a result, low-harmonic drives, devices with active front ends and active filters that mitigate harmonic distortion for a whole set of motors are now crucial elements – especially because power levels now extend to several megawatts, even with low-voltage devices.

Energy efficiency
Drive technology is taking on another important duty for the future: using energy efficiently, and variable speed drives are the first choice when it comes to energy efficiency. They control pumps for reliable water supply and wastewater treatment, they run air conditioners, ensure reliable operation of conveyer belts, warrant the power supply of cargo ships and ensure you arrive safely on the fifth floor. In all of this, they achieve considerable energy savings and process optimisation.

This is now being recognized by legislators. The Ecodesign Directive is the legislative framework that sets requirements on all energy related products in the domestic, commercial and industrial sectors throughout Europe. The main goal of the directive is to improve the energy efficiency of products throughout the EU and here variable speed drives play a pivotal role. This trend will expand to the world’s legislative boards over the coming years, and we will see an increasing demand for accurate control and measurements of energy consumption.

Process optimisation
Today’s production facilities are often text book examples of optimisation. Speed control of motors, according to changing plant requirements, improves process control, which is essential to ensuring high product quality. Accurate control will also have a positive impact on operational efficiency, material usage, environmental emissions and production yield.

At the same time, plant managers have strict requirements of their drives in terms of dimensions (cabinet space), heat emissions, ingress protection ratings, connectivity and ease of service. Customers and suppliers nowadays collaborate more closely to find the optimum match of product to process. 

With their diminishing size, increasing capabilities and growing intelligence, variable speed drives have become an indispensable element of industrial automation. In the present economic climate, reducing total life costs and optimising system performance without compromising product quality, are crucial in the early stages of plant and process design, and flexible products that help designers meet these objectives will be much in demand.

An impartial guide to saving energy with variable speed drives has been prepared by Danfoss and is available to read here.

Sara Bernard is with Danfoss VLT Drives in the UK

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