Tag: variable speed drives

  • Variable Speed Drives in Food and Beverage Plants: Where They Pay and Where They Bite

    Variable Speed Drives in Food and Beverage Plants: Where They Pay and Where They Bite

    The Most Useful Box in the Switchroom, and the Most Misunderstood

    Variable speed drives have transformed production plants. A conveyor that once ran at one speed now follows the filler ahead of it. A pump that once ran flat out against a throttled valve now delivers exactly what the process needs. Drives save energy, reduce mechanical wear and give control that fixed speed motors cannot.

    They also bring problems that fixed speed motors never had, and plants that install them without understanding those problems pay for it in failed bearings, tripped capacitor banks and unexplained faults. This guide covers where variable speed drives earn their keep in a food or beverage plant and where they bite.

    What a Drive Does

    A variable speed drive, also called a variable frequency drive or VSD, sits between the supply and a motor. It converts the incoming supply to direct current and then builds a new output whose frequency and voltage it controls. Since the speed of an induction motor follows the frequency it is fed, the drive controls speed.

    That gives three things at once: adjustable speed, controlled acceleration and deceleration, and a low starting current. A drive can bring a loaded motor up to speed smoothly while drawing no more than about its normal running current from the supply.

    Where They Pay: The Affinity Laws

    The strongest case for a drive is on centrifugal pumps and fans, and the reason is a set of relationships known as the affinity laws. For these loads, flow is proportional to speed, pressure is proportional to the square of speed and power is proportional to the cube of speed.

    The cube is what matters. Slow a fan or pump to 80 per cent of full speed and it delivers 80 per cent of the flow, but the power required falls to about 51 per cent. At 90 per cent speed, power is about 73 per cent.

    Many pumps and fans are sized for a peak that rarely occurs and are then throttled with a valve or damper for the rest of the time. Throttling wastes the energy the motor has already consumed. A drive achieves the same reduced flow by slowing the motor, and the saving is often large.

    Good candidates in a beverage plant include cooling tower and condenser fans, glycol and chilled water circulation pumps, CIP supply pumps, ventilation and extraction fans, and process pumps whose demand varies through the day.

    Where They Pay: Control

    On conveyors and many process machines the load is not centrifugal, the cube law does not apply and the energy saving is modest. The value of the drive is control.

    Speeds can be matched along a line so that product neither gaps nor backs up. Starts and stops are gentle, so containers do not topple and belts and chains last longer. A recipe can set speeds for each product at changeover. Mixers and agitators can run at the speed the product needs and start against a heavy load.

    Where They Do Not Pay

    A drive is not free to run. It has losses of its own, typically a few per cent of the power passing through it. A motor that runs at full speed and full load all the time will use slightly more energy with a drive than without one. If the only requirement is a gentle start, a soft starter does that job for less money and with no running losses once it is bypassed.

    The test is simple. Does the speed need to change, or would the process benefit if it could? If not, a drive is probably the wrong tool.

    Where They Bite: Harmonics

    Drives draw current from the supply in pulses and not as a smooth wave, which creates harmonic currents. In a plant with a few small drives this is unnoticeable. As the proportion of load on drives grows, the distortion grows with it.

    The symptoms are overheated neutrals and transformers, nuisance tripping and interference with sensitive equipment. The most expensive symptom involves power factor correction. Capacitor banks can resonate with the supply at a harmonic frequency, amplifying the distortion and destroying the capacitors. Any site with both drives and correction equipment should have harmonics measured, and correction equipment should be of the detuned type, with reactors fitted, where the measurements call for it.

    Harmonics can be reduced at the drive with line reactors or filters, and by specifying low harmonic drives for large installations.

    Where They Bite: Bearing Currents

    The fast switching inside a drive induces a voltage on the motor shaft. That voltage can discharge through the bearings, and each discharge leaves a microscopic pit in the bearing race. Over months the pitting forms a washboard pattern, the bearing becomes noisy and then fails.

    This is a common cause of repeated bearing failures on motors retrofitted with drives, and it is often misdiagnosed as a lubrication or alignment problem. The remedies are shaft grounding rings, insulated bearings on larger motors, correct earthing and proper motor cable. If a motor on a drive is on its second or third set of bearings, look here.

    Where They Bite: Cable Length and Motor Insulation

    The output of a drive is a series of very fast voltage pulses. On a long cable run those pulses reflect at the motor terminals, and the peaks can reach well above the nominal voltage. Older motors, and motors not designed for drive duty, can suffer insulation breakdown as a result.

    The risk rises with cable length. Where a drive is in a switchroom and its motor is a long way down the plant, check the drive manufacturer’s limits and fit an output reactor or filter where they are exceeded. When retrofitting a drive to an old motor, check that the motor is suitable.

    Where They Bite: Heat, Water and Dust

    Drives are electronic equipment and heat shortens their life. They need clean, cool air. In a food plant that is a real constraint. A drive mounted on a machine in a washdown area needs an enclosure rated for it, and an enclosure tight enough to keep water out also keeps heat in. Blocked filters and failed cooling fans are behind a large share of drive failures. Drive filters and fans belong on the maintenance schedule.

    Other Things to Get Right

    Cabling and earthing. Drives generate electrical noise. Screened motor cable, terminated correctly at both ends, and separation from signal cables prevent interference with sensors and instruments.

    Motor cooling at low speed. A standard motor is cooled by a fan on its own shaft. Run slowly under load for long periods, it may overheat. Some applications need a separately driven cooling fan.

    Parameters. A drive has dozens or hundreds of settings. Back them up. A replacement drive fitted at three in the morning with factory defaults will not run the machine.

    Safety functions. Many drives offer safe torque off, which is useful in a properly designed safety system. It is a control function and not electrical isolation. Maintenance still requires the supply to be isolated and locked.

    Bypass. For critical equipment such as refrigeration, consider whether the motor needs a way to run if the drive fails.

    A Note on Motor Efficiency Rules

    Australia sets minimum energy performance standards for three phase electric motors, and those requirements have been under review. If you are buying motors as part of a drive project, confirm the requirements in force at the time of purchase instead of relying on older guidance.

    Checklist Before You Fit a Drive

    Will the speed actually vary? Is the load centrifugal, where the saving is large, or constant torque, where the benefit is control? Is the motor suitable for drive duty? How long is the cable run? Where will the drive sit, and how will it be kept cool and dry? What harmonics are already on site, and is there power factor correction? How will it be controlled, and who will hold the parameter backup? Has the safety design been considered?

    Where BevTech Fits

    BevTech is a family owned engineering business in Richlands, Brisbane, with more than 25 years in beverage and FMCG manufacturing. Our industrial electricians install, commission and fault find variable speed drives on conveyors, pumps, fans and refrigeration plant, and our automation engineers integrate them with Allen Bradley and Siemens control systems, as on a Siemens S7-1500 project controlling glycol refrigeration for beer tank temperatures. Because our mechanical trades and machine shop are in the same business, a bearing problem on a driven motor gets looked at from both sides.

    If you are considering drives for a pump or fan system, or have drives that keep causing trouble, use the contact form at bevtech.com.au/contact.

    The figures in this article are illustrative. Actual savings depend on the system and how it is operated, so have the application assessed before committing to a project.

  • Energy Efficiency Retrofits for Beverage Manufacturing Equipment

    Energy Costs as a Growing Operational Pressure

    Rising electricity costs have moved energy efficiency from a background consideration to a genuine operational priority for many Australian beverage manufacturers. Refrigeration systems, compressed air, pumps, and heating processes such as hot water rinse and clean in place cycles are among the largest energy consumers on a typical beverage production site, and in many cases, the equipment and control systems managing these processes were designed years ago, when energy costs and efficiency expectations were significantly different. Retrofitting existing equipment for improved energy efficiency, rather than waiting for a full equipment replacement cycle, is an increasingly practical option worth genuine consideration.

    Refrigeration: The Largest Opportunity on Most Sites

    Refrigeration systems, whether supporting beer tank temperature control, cold storage, or process cooling, are typically among the most energy intensive equipment on a beverage manufacturing site, and also among the areas offering the greatest potential for efficiency improvement through control system upgrades rather than full mechanical replacement. Older refrigeration control systems often run on relatively basic thermostatic or fixed setpoint logic, cycling compressors on and off in response to simple temperature thresholds without accounting for factors such as ambient conditions, actual production demand, or the efficiency losses associated with frequent compressor cycling.

    Upgrading refrigeration control to a modern PLC based system, of the kind BevTech has implemented using Siemens platforms and ABB variable speed drives for glycol refrigeration applications, allows significantly more sophisticated control logic: modulating compressor and pump speed to match actual cooling demand rather than simple on off cycling, and optimising setpoints based on real time conditions rather than fixed, conservative values set at original commissioning. This kind of control upgrade can often be delivered without replacing the underlying mechanical refrigeration equipment, making it a comparatively cost effective efficiency improvement relative to full system replacement.

    Compressed Air: The Hidden Cost Centre

    Compressed air is frequently described as the most expensive utility on a manufacturing site relative to its actual delivered energy, because of the significant conversion losses inherent in generating and distributing compressed air compared to using electricity or other energy sources more directly. Leaks in ageing compressed air distribution systems are extremely common and often go unaddressed for years, since individual leaks rarely cause an operational problem, they simply waste energy continuously in the background.

    A structured compressed air audit, identifying and repairing leaks, reviewing system pressure settings for unnecessary margin above actual equipment requirements, and assessing whether compressor control strategy matches actual demand patterns across a production shift, frequently identifies meaningful energy savings with relatively modest investment, particularly on sites where the compressed air system has not been reviewed since original installation.

    Hot Water and CIP Systems: Precision Over Conservative Margins

    Hot water rinse and clean in place systems, essential to hygiene compliance in beverage manufacturing, are also significant energy consumers, given the water heating and pumping involved. Older systems are frequently controlled with generous safety margins built into temperature, flow, and cycle time settings, reflecting a conservative approach at original commissioning rather than precise, validated requirements. Reviewing and, where appropriate, tightening these parameters, supported by more precise temperature and flow sensing and control logic, can reduce energy and water consumption without compromising the hygiene outcomes the system exists to deliver.

    This is a genuine engineering balance rather than a simple efficiency exercise, since hygiene compliance cannot be compromised for the sake of energy savings, but many existing systems carry more conservative margin than is genuinely required once actual process validation data is properly reviewed.

    Motor and Drive Efficiency

    Older fixed speed motors running conveyors, pumps, and fans throughout a production facility represent another common efficiency opportunity. Retrofitting variable speed drives to motors that were previously running at fixed speed regardless of actual demand allows motor speed, and therefore energy consumption, to be matched to actual process requirements. This is particularly effective on pump and fan applications, where energy consumption relates non linearly to speed, meaning even modest speed reductions during periods of lower demand can deliver meaningful energy savings.

    Building a Realistic Retrofit Business Case

    The business case for energy efficiency retrofits should be built around genuine, measurable opportunities rather than generic assumptions. This starts with identifying the largest energy consumers on a specific site, refrigeration, compressed air, and heating processes are common candidates but the actual priority varies by facility, and assessing where control system or equipment upgrades offer the clearest path to reduced consumption without unacceptable capital cost or production disruption. Metering and monitoring existing energy consumption, even at a relatively basic level, provides the baseline data needed to validate savings once a retrofit is implemented, and to prioritise which opportunities to pursue first.

    Measuring and Verifying Actual Savings

    A retrofit project is only genuinely successful if the anticipated energy savings are actually realised and can be demonstrated, rather than assumed based on theoretical calculations alone. Installing basic metering before a retrofit is implemented, whether on a specific refrigeration system, compressed air installation, or a broader section of a facility, provides the baseline needed to measure actual consumption before and after the change. This verification step matters both for validating the specific project’s business case, and for building a manufacturer’s confidence in pursuing further efficiency initiatives based on demonstrated, rather than theoretical, results.

    Where energy efficiency projects are pursued partly to support broader sustainability reporting or ISO 14001 environmental management objectives, this measured, verifiable approach to savings also provides genuinely credible data for that reporting, rather than estimates that may not withstand scrutiny from customers or certification auditors.

    Considering Government Incentives and Support Programmes

    Various state and federal programmes periodically offer incentives, rebates, or co funding for industrial energy efficiency projects, particularly those involving measurable, verified savings of the kind described above. While the specific programmes available change over time, manufacturers planning a significant retrofit project are generally well served by checking current eligibility before finalising project scope, since available incentives can materially improve the business case for equipment or control system upgrades that might otherwise sit on the margin of being cost justified.

    An Incremental, Evidence Based Approach

    Energy efficiency retrofits do not need to be pursued as a single large capital project. A staged approach, starting with the highest value, most clearly justified opportunities such as refrigeration control upgrades or compressed air leak repair, allows manufacturers to build genuine evidence of savings before committing to broader retrofit programmes across a facility. With combined mechanical, electrical, and automation capability, BevTech supports FMCG manufacturers through this process, from initial energy use assessment through control system and equipment retrofit delivery. To discuss energy efficiency opportunities on your production site, contact BevTech at 25 Silvio St, Richlands QLD 4077, or admin@bevtech.com.au.

@Fd2X@HoSi10178
Shutdown Checklist
Bevtech fmcg beverage shutdown planning checklist glass.webp0000

Get Your FMCG & Beverage Plant Shutdown Planning Checklist

We wont spam you :) or share your details.
We will send you an email with the PDF checklist.