Benefits of Using a Variable Speed Drive

Benefits of Using a Variable Speed DriveApproximately one third of the world’s electrical energy is supplied by electric motors in fixed-speed centrifugal pump, fan, and air compressor applications. This proves thatsignificant energy efficiency improvement opportunities are available by applying variable speed drives to electric motors.

Variable speed drives have over the past decade allowed to become a cost efficient way to reduce energy costs and increase system production efficiency. Today variable speed drive manufacturers around the globe are finding more ways to benefit production processes by applying variable speed drives to manufacturing equipment .

Variable speed drives can reduce energy costs up to 50% by speed reduction on applications where the full speed (RPM) of the electric motor is not required.This energy savings is often significant enough to pay for the variable speed drive within a couple of months.

Variable Speed Drive Applications

Benefits of Using a Variable Speed DriveVariable speed drives are used in many applications such as swimming pool pumps, air compressors, conveyor belts, lathes, mills, food processing production lines, waste water treatment pumps, HVAC fans and blowers, and many more applications in the industrial manufacturing world. Variable speed drivesare often used in manufacturing facilities to increase or decrease the acceleration and deceleration times on alternating current (AC) motors. Adjusting the acceleration and deceleration timeon an AC motor can add years to the lifespan of an AC motor, and can also improve efficiency on production demands. Variable speed drives can also provide the ability to be programmed to control the frequency of starting and stopping an AC motor.This ability provides a means by which an AC electric motor is only operating when needed for the equipment it’s rotating. AC electric motors have a longer lifespan if they are not continuously operating when they don’t need to be.

Variable speed drives have an average lifespan of up to about 8 years from fractional horsepower through about 10 horsepower, but larger horsepower drives have a longer lifespan which creates a market for manufacturers to use variable speed drive repair centers. Variable speed drive repair centers work closely with manufacturers to keep production at a maximum while reducing production downtime.To learn more about variable speed drives or for variable speed drive repair and replacement quotes, contact Precision Electric, Inc.



ABB Low Harmonic Drives

Harmonic distortion may disturb or damage sensitive equipment connected to the same circuit of a variable speed drive. Any distorted voltage and current waveform that deviates from the ideal waveform presents the potential to harm electronic components, which can result in expensive repairs and production downtime. Non-linear loads connected to the electrical supply in industrial and commercial facilities insert harmonic distortion on the power distribution system.

A non-linear load application included solid state electric motor soft starts, variable speed drives, personal computers, electronic lighting, welding equipment and other power supplies that are not interrupted. Harmonic distortion can cause distribution transformers and supply cables to overheat; resulting in the breakdown of electrical insulation and failure; electronic display failure, circuit breaker tripping and other damage resulting in distorted readings by metering equipment.

Taking action to solve harmonic distortion provides many benefits beyond managing risk. Industries with high power consumption such as paper and pulp, metals, oil and gas refineries, cement and chemical processing, have the opportunity to optimize the power quality in these facilities by managing the disturbances and losses that are caused by harmonic distortion.

A Single Solution to Harmonic Distortion

ABB Low Harmonic DrivesHarmonic standards are becoming stricter and there is a growing demand for low harmonic drive solutions. The ABB ACS800-U31 variable speed drive offers an easy solution to the problem of harmonics. The solution itself is incorporated within the variable speed drive, eliminating the need for any additional filtering equipment or complicated large multiple pulse transformer installations.

The ABB ACS800-U31 eliminates low order harmonics with the active converter controlled with DTC technology and high order harmonics with an LCL line filter. The result is exceptionally low harmonic content within the network that exceeds the requirements made by IIEEE519 at the drive input terminals. Even on the weakest AC line network the ACS800-U31 can be a solution to harmonic distortion. The ABB ACS800-U31 provides a simple, compact and complete solution to meet power quality standards.

The ABB ACS800-U31 doesn’t require a dedicated multiple pulse transformer so the installation time is significantly reduced with regards to cabling and wiring processes. The ABB ACS800-U31 also requires less physical floor space which also makes ease of installation. The ABB ACS800-U31 always operates with unity power factor of 1 and is impervious to alternating current line voltage imbalances up to and over 3%. The system efficiency also is better than 12 and 18 pulse drive solutions since there isn’t a phase shifting transformer required for applications.

The ACS800-U31 is a ultra low harmonic wall mounted drive and is available in power ratings from 208-240 voltage from 10 horsepower through 60 horsepower; and 380-480 voltage from 20 horsepower through 125 horsepower.

To learn more about ABB ACS800-U31 low harmonic drives, please visit the ABB Website.


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Variable Frequency Drives for Wastewater

The flow and pressure of fans and pumps need to be controlled because water consumption varies during a day.The flow and pressure can be adjusted either electrically with variable speed drives or mechanically with fixed-speed solutions such as inlet guide vanes, throttling valves or hydraulic couplings. The most common flow control method is by means of a fixed speed motor regulated with a valve. This method can be compared to adjusting the speed of a car by braking while keeping the foot on the gas pedal. This technique doesn’t only waste a tremendous amount of energy, it also wears out the equipment. With variable frequency drives, changing the flow is achieved by adjusting the motor speed which can be compared to reducing the speed by taking the foot on the gas pedal and switching the automobile into lower gear. Wastewater pumps are operated at best efficiency point under all operating conditions when using a variable frequency drive with the application. Variable speed drives are the most efficient control method because they save energy and they decrease water emissions while minimizing total operating costs.

Variable frequency drives can also reduce maintenance overhead at waste water plants by acting as soft starters when applied to electric motors; because they reduce the stress on bearings, motor windings, housings and other equipment. The variable frequency drive progressively increases the motor speed and accelerates the corresponding load to the rated RPM of the motor. When sized correctly, one variable frequency drive can be setup to operate several wastewater pumps in sequence.

Using a variable frequency drive for soft starting electric motors eliminates high starting currents and voltage dips that normally would cause breakers to trip on overload fault. When a wastewater pump is turned off or if the water demand is reduced, a variable frequency drive can slowly reduce the speed of the pump to avoid water hammering, stress on pumping equipment and electric motor parts, resulting in an extended lifetime of wastewater pumps and electric motors. A pump running at half its rated RPM consumes as little as one eighth of the energy compared to a pump running at full rated RPM.Wastewater pumps usually operate at partial load so a huge potential in energy savings can be achieved by controlling a pump’s RPM with a variable frequency drive. Applying a variable frequency drive to wastewater pumps instead of operating across the line, an energy bill can be reduced by as much as 60 percent and this consequently helps to reduce water emissions.

ABB Drive Solutions for Wastewater Pumps

Variable Frequency Drives for WastewaterThe ABB ACS 2000 ULH direct-to-line configuration combines the cost savings of a variable speed drive systems without using a transformer and features the benefits of a voltage source inverter, including excellent availability, reliability, and high, constant power factor with superior control performance.

The ABB ACS 2000 drive features an active front end combined with multiple levels of control. The result is an ultra-low harmonic design that minimizes line harmonics without the use of expensive, custom transformers. The ABB ACS 2000 also includes a smaller, lighter weight packaged product to minimize the overall space required in the maintenance room while reducing shipping and installation costs.

Power ratings of the ABB ACS 2000 series drives range from 400 kVA through 300 kVA to 2000 horsepower.and 4.16 kV, 6.0 kV to 6.9 kV. The ABB ACS 2000 series drive is commonly used on influent, effluent pumps, aeration blowers, cooling fans, intake pumps and other related wastewater equipment.

To learn more about the ABB ACS 2000 series drive, please visit the ABB Website.


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