Driving down costs with motors and drives

Escalating demands to save energy have lead suppliers to develop new, more efficient motor and drive systems. Sarah Falson investigates.

WITH the carbon tax in motion and energy prices rising by the month, there has never been a better time to assess factory equipment running costs.

However, taking in to account the array of systems used in production, it can be difficult to identify areas where savings can be made.

According to NORD Drivesystems AU regional sales manager Victoria, Tasmania & South Australia, Tony Sculpher, manufacturers should begin by auditing the energy-hungry equipment at the heart of the production line: the motor and drive systems. 

“Here in Australia, the consumption of electric power by electric motors accounts for approximately one-third of all electric power generated. Electric motors are the single largest consumer of electric power as one identified group,” Sculpher told Manufacturers’ Monthly.

“This is why the Australian and New Zealand authorities created the Minimum Efficiency Performance Standard (MEPS), also known as the AS/NZS1359.5 Standard, which covers all three-phase electric motors between 0.73 kW and 185 kW.”

Know your system

A good way to start, Sculpher says, is to ensure factory equipment is properly matched to the job at hand. Next, manufacturers can work out if their motor systems are using surplus energy.

“An electric motor running continuously at full load current requires investigation to confirm its correct size selection. A frequency inverter with flux optimisation software can minimise the usage of full load current when it is not actually required,” he explained.

“Further consideration is required to ensure that the gearbox with the most efficient gear set is utilised, as this further enhances the efficiency of the total drive package.”

Sculpher says manufacturers often make the mistake of purchasing a drive system based on price, forgetting the operating and maintenance costs throughout the life of the system vary depending on the unit.

“Many drive systems are often selected by a secondary source, for example an original equipment manufacturer or a design engineer, and these decisions are based on their purchase cost, and for the selection to remain competitive against competition,” warned Sculpher.

“For a manufacturer or end-user who requires the most efficient drive system package, he must identify the efficiency goal for his installation, and communicate his preferences to the selection source. Many customers do not take enough ownership of this energy saving and efficiency requirement, simply assuming they will be offered the ‘best performance’ drive package by the supplier. 

“Some do not appreciate that they do indeed have the power to specify what they exactly want. After all, the one paying the bills for both the initial purchase and for the long-term running is the end-user!”

Taking advantage of the expertise offered by maintenance managers or an offsite contractor can help identify problems and advise where energy savings are possible, Sculpher advises.

“Where there are a large number of drive packages onsite, the opportunity for efficiency and energy savings are greatly increased. Management must drive their maintenance providers for these efficiency and energy gains, and this will require communication, education, and a concentrated effort (read cost) to identify those drive packages which do not meet their goals,” he said.

Invest to save

Bonfiglioli Transmission application sales engineer, Electronic Automation, Steve Dumbrell, also recommends conducting a motor audit to identify areas for potential savings.

“Audit your plant to work out: what motors you have; what kW size; what application they are being used for; and whether or not the resultant effect of the motor is being reduced by other means – for example, pumps flow being reduced by manual flow valves after the motor,” he told Manufacturers’ Monthly.

“Once you have this basic information, I would look at the applications that the motor is running at full speed where the effect of the motor is being limited, as in a control valve limiting water flow or the motor continually being turned on and off due to it overworking the application. These will be the areas that have the largest potential to give the greatest return.

“If you find you have applications that are being restricted you are in a very good position to benefit from an external energy audit.”

Dumbrell also suggests using variable speed drives (VSD) to manage motor output: “VSDs are generally around 94-98% efficient. In many pumping applications it can be very cost-effective to replace the direct-on-line start with a VSD. This can see installation payback in some cases less the 12 months,” he said.

“Many manufacturers install VSDs to simply allow the machine to have a variable speed, but modern VSDs can also have a variety of industrial sensors connected to them to allow the drive to control the process better – with more control – and therefore save on the cost of a PLC [programmable logic controller] or separate controller.”

Dumbrell says suppliers are constantly updating drive designs to improve energy efficiency.

“Drive manufacturers are looking at ways to make their VDSs more appealing to the customer and are starting to design the drives with low-loss drive filters, sleep modes to reduce energy consumption when the motor is not running, and load monitoring which will optimise the motor current to the application to reduce energy supplied to the motor,” he said.

“Technology has improved greatly in the last 10 years with a large effort being spent on improving environmental footprint, meaning businesses can actually save a lot of money by reassessing how they use energy in the day-to-day running of their business.”

Dumbrell warns that even though producing clean energy can be expensive – especially in the case of sun and wind generation – investing in energy-saving equipment will reduce running costs both in the short- and long-term.

“I feel the government would be better subsidising energy audits and once businesses realise how much they can save they will start to implement change themselves,” he said.

Assistance available

Recognising the key role energy-efficient equipment plays in reducing carbon emissions, the government is now providing assistance for industry to invest in ‘clean’ technology.

ABB energy efficiency manager – motors & drives, Shailesh Sharma, believes this funding delivers a compelling argument for manufacturers to begin reducing energy consumption.

“Clean technology and energy efficiency grants from the government are the cost-effective way to apply replacement or upgrades of existing installations to support energy efficiency,” Sharma told Manufacturers’ Monthly.

“Being more energy-efficient makes economic sense because it lowers operating costs. From an environmental perspective, it is an effective way for businesses to cut carbon emissions.

“Energy efficiency represents a multiple opportunity for cost reduction, contribution to sustainability and environmental commitment. Short return of investment based on net present value is very attractive for any business-owner investing in energy efficiency projects.

“More publicity for government grants and incentives for the industry is required. Government should come up with loan options or such incentives for the industries that are not covered by current grants. This would allow all sizes of industry to access capital to apply energy efficiency.”

A number of grants are available, most recently through the Clean Energy Future scheme, which is part of a long-term plan to reshape Australia’s economy, cut carbon pollution, drive innovation, and help avoid the increased costs of delaying action on climate change.

The plan comprises three separate initiatives: the Clean Technology Investment Program; Clean Technology – Food and Foundries Investment Program; and Clean Technology Innovation Program – which are now open for registrations.

Funding has also been designated for supply chain initiatives and the steel industry.

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