Energy-saving drive technology for machines
70% of the power consumptions of the industry are allotted to three-phase motors with constant speed according to the Commission of the European Communities. The energy consumption of these motors, Commission says, can be lowered by 20% to 30%. That succeeds in particular via the electronic speed regulation of motors by high-efficient frequency converters and servo converters. For this purpose food processing machines offer many starting points.
July 15th, 2010 - The regulation No 640/2009 of the Commission with regard to ecodesign requirements for electric motors specifies that certain motors must be equipped with electronic speed regulation starting from 2015.
The following examples show how modern drive technology both increases the performance of the machine and saves energy.
Electronic speed regulation saves energy with pumps...
- Losses with common regulation of pump
Continuously changeable speeds in food processing machines optimise the production speeds and achieve at the same time a higher economic efficiency. So the example of a pump regulation shows how throttling losses can be compensated by electronic speed regulation.
...and with shredding machines
- Cutter with the frequency converter Unidrive SP of Control Techniques
Shredding machines such as Cutter have strongly variable torques. At this point the electronic speed regulation with frequency converters permits to provide different speeds of the cutter block depending on products. This optimises energy consumption and protects food, motor and mechanics.
Energy saving function lowers power losses by more than 75%
Frequency converters with internal energy saving function permit the dynamic adaptation of the asynchronous motor’s voltage-frequency-characteristic to the load. This drastically reduces the magnetisation and the current in the no-load operation. As consequence the power loss declines by more than 75% and reduces the heat dissipation of the motor.
Reducing starting currents and losses
- Motor with direct power up and with frequency converter
Speed adjusted electric drives offer huge energy saving potentials when raising and braking of systems are concerned. The direct power up of the motors requires extremely high starting currents accordingly with high energy costs. Frequency converters, however, reduce these high starting currents and protect at the same time the mechanics.
Modern servo drives activate energy saving potentials
- Vacuum filling machine with frequency converter Unidrive SP of Control Techniques
Highly effective servo-drives reduce the energy demand because they do not produce magnetising current lowering the losses. Therefore they are ever more frequently implemented in today's modern machines and food processing machines.
So modern and low-inertia servo motors lead to higher output rate by ever more dynamic motions with high cycle rates. At the same time they ensure an optimal energy balance.
Energy can often be saved if gearbox- afflicted drives are substituted by direct drives. That makes at the same time the machine more compact, reduces the losses and saves thereby energy costs.
- Dr. Holger König is Head of Sales and Application at Control Techniques at Hennef, Germany
Finally in many manufacturing processes peak pressures are only required for short time. A dynamic closed-loop control of the pumping pressure can save here also much energy by modern servo drives.
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