Motors and Drives: Control and efficiency shape the industry

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PACE 60-year Anniversary Series:  Motors & Drives
supported by SEW-Eurodrive

Ask any industrial business-owner today and they will tell you that gaining and achieving efficiency is the main impetus behind the majority of major business decisions – especially where capital equipment is concerned.

Whether for environmental or cost efficiency – or both – finding faster, cheaper, more consistent ways of doing things has been an ongoing objective for plant-owners throughout Australia’s manufacturing and processing history.

At the heart of the production line, motor and drive systems have offered a prime opportunity for efficiency gains over the years, with engineers looking for features such as smooth operation and speed control since back in the 1960s.

According to WorleyParsons Limited principal engineer – instrumentation and control, Ian H. Gibson, the invention of the variable-speed drive (VSD) was one of the most memorable developments in the technology over the last 50 years, affording manufacturers much more control over their operations.

“My first home-made VSD control system had a mechanical speed variator, fitted with a pneumatic cylinder positioner, driving a small Mono pump back in about 1964. This was feeding PVC slurry to a spray dryer on outlet temperature control. The manufacturer of the dryer said it couldn’t work; two years later I found them using a copy on their milk dryers,” Gibson told PACE.

Allen-Bradley Programmable Controllers manufactured in the 1980s (Image courtesy of Rockwell Automation).

Allen-Bradley Programmable Controllers manufactured in the 1980s (Image courtesy of Rockwell Automation).

Gibson designs and commissions process plant control systems for a variety of sectors, including offshore and onshore oil and gas, and minerals processing. Having worked in the industry for 55 years, he has experienced first-hand the drive’s evolution from a simple mechanical unit to the sophisticated models now selling on the market.

“Early came the various mechanical systems, with variable pitch pulleys or similar devices, then hydraulics with variable capacity pumps and/or motors. The electromechanical couplings (eddy-current couplings) which were grossly inefficient, DC electrical drives, then the first of the AC variable frequency drives – unreliable and bulky,” Gibson said.

“Then came the silicon revolution, as reliability increased while size and cost plummeted. Now they are commodity items, sold (and bought) in many cases by folk who know little about the application theory. The hydraulic and mechanical drive systems are still out earning their keep.”

Varying speed

ABB Automation Products Division drives service engineer, Stefan Ludomir Ostrowski, has worked in the industry for 40 years and agrees that the efficiency benefits offered by the VSD have made it a mainstay in processing plants across the country.

“At the beginning, electric motors were started DOL (Direct On Line) or by a Star/Delta switch, and the speed of a machine was adjusted mechanically by gear boxes. Later, as thyristors were invented, analogue drives came in use so variable speed adjustment could be implemented both in scalar and vector controls,” he told PACE.

“Now, almost all plants use digital VSDs for efficiently controlling manufacturing processes, saving energy and the environment.”

Underground mining conveyors driven by VSDs have replaced on-wheel transport driven by man-power for one of Australia’s largest coal export terminals on Kooragang Island (Image courtesy of NCIG).

Underground mining conveyors driven by VSDs have replaced on-wheel transport driven by man-power for one of Australia’s largest coal export terminals on Kooragang Island (Image courtesy of NCIG).

One of Ostrowski’s customers, Newcastle Coal Infrastructure Group (NCIG), uses VSDs to drive underground mining conveyors at its Kooragang Island coal export terminals, replacing labour-intensive, on-wheel transport driven by man-power.

Thirty-two medium-voltage drive systems, rated at 1000 and 1250 kW, provide soft start, and speed and torque control for the 20 conveyors; eight conveyors feature a single drive each, while 12 have two single drives each in a master-follower arrangement.

“Among the benefits are energy savings, accurate and fast load sharing, high availability and smooth ramp-up,” said Ostrowski.

A typical motor built and used in the manufacturing industry in the 1960s (Image courtesy of WEG).

A typical motor built and used in the manufacturing industry in the 1960s (Image courtesy of WEG).

In the future, drives will continue to play an important role across industries, helping new and emerging sectors reap environmental and cost savings, according to Ostrowski.

“Renewal/green energy such as wind and sun could not be harnessed without inverter technology, which is an integrated part of drives,” he said.

Flexible manufacturing

In the manufacturing industry, companies have become increasingly reliant on motor and drive systems over the years – not just in their processing lines but also incorporated in to manufactured products themselves.

When lifting equipment manufacturer JDN Monocrane was founded in 1979, the team began exploring drives for both smooth operation and speed control.

“In our industry of overhead crane manufacture, hoisting zero speed lock rotor applications were the commencement of drive applications,” JDN Monocrane managing director, Colin Smith, told PACE.

“Drives have evolved tremendously in terms of usability, increased functionality and improved reliability. Drives are an integral part of our modern crane design, and are used in approximately 90% of our product sold.”

Appliance manufacturer Fisher & Paykel also relies heavily on motors and drives, with the technology playing a critical role both on the production floor and in the products being made. Motor technology director, Gerald Duncan, claims drives in particular have played a very special role in the company’s history, ever since he began his employment 35 years ago.

“We made a wide range of appliances – everything was made under licence in a protected industry. We used variable speed brush-type DC motors in the Hoovermatic washing machines, but everything else used fixed speed induction motors imported from wherever we could. They were what the rest of the world was making at the time,” he told PACE.

“The writing was on the wall for protected manufacturing in this part of the world and so we developed a research facility to start looking at where technology could help us. At this time microprocessors were coming on the scene and numerically-controlled machine tools were more common. Our dream was to use the emerging technologies of the numerically-controlled machine tools and microprocessors to make flexible manufacturing machinery.”

March 7, 1902 - The first Allen-Bradley Motor Starter - 40HP, 110V, Direct Current (Image courtesy of Rockwell Automation).

March 7, 1902 – The first Allen-Bradley Motor Starter – 40HP, 110V, Direct Current (Image courtesy of Rockwell Automation).

In the 1980s, the team began introducing electronic drive systems to their production lines, and soon realised that they could apply this same principle to the products coming off the manufacturing line. The result was the Smart Drive clothes washer: the world’s first appliance incorporating Brushless Direct Current Motors.

“Our small size and low volumes in this part of the world meant we had to look to technology to give us a competitive advantage. At that time our manufacturing plants were highly labour intensive and capable of only making a few products that were licensed from large overseas appliance manufacturers,” Duncan said.

“We had a desire to implement flexible manufacturing machinery. To enable this we developed in house microprocessor-controlled motion controllers using variable speed DC motors and stepper motors. At that time commercial motion control systems were not yet available.

“From this base the manufacturing plants that have been developed look space-age compared to the first manufacturing plants we had. The modern flexible manufacturing lines are completely dependent on stepper motors, variable speed motors and brushless DC motors, which were crucial in this development.

“In the early years almost all electric motors were fixed speed induction motors. Variable speed was possible using brush type motors, but these had issues. The brushless DC motor gave all the advantages of variable speed without the previous limitations of the brush type motors.

“In the manufacturing environment for Fisher & Paykel the major milestone in electric motors and drives was the introduction of numerical controls. This made possible the design and development of flexible manufacturing machinery that could manufacture components in a variety of sizes and configurations on demand.

The result was a manufacturing system that could manufacture a large variety of products in a mixed flow environment where each successive product on an assembly line could be quite different to the previous.”