ABB Energy Management Systems

Today industry and commerce are facing an energy challenge. Pressures to reduce energy consumption, lower carbon dioxide emissions and provide secure power supplies are coming from governments, consumers, legislators and shareholders alike. All of these pressures are against a background of ever-rising energy prices and the dramatic effects climate change ishaving on the environment. As a result, industry and their consumers are demanding ever more energy-efficient products.

The worlds demand for energy is rising steadily. Under current policies, energy demand is set to rise 47 percent between 2008 and 2035, according to the International Energy Agency (IEA), reflecting global economic growth and rising living standards. Electricity demand is expected to grow almost twice as fast, with most of the increase occurring in emerging markets.Helping industries and utilities improve energy efficiency Industry consumes about 42 percent of all electricity generated, according to the IEA. The most energy-intensive industries are cement, chemical, iron and steel.

The energy saving potential in industries and utilities is enormous just in electric motor-driven applications alone: hundreds of millions of electric motors driving machines, compressors, fans, pumps or conveyors in virtually every sector account for about 70 percent of all the electricity that industry uses.More than 90 percent of industrial motors either cannot adjust their power consumption or use very crude methods to do so. Many of these electric motors always run at full speed, regardless of the actual output needed. In many applications, energy use can be cut to one- eighth just by reducing the motor speed by half.

ABB Energy Management Systems Solutions

The most immediate, cost-effective and practical way to address the energy challenge is to grasp the opportunities for energy reduction that come from using energy more efficiently with available and proven technology.ABBenergy management systems include variable frequency drives, motors and other technologies tohelp lower energy use, either by reducing power consumption and losses, improving productivity or through better management of equipment.

With ABB energy management systems there is great potential to save energy and costs in industry. Nearly 70 percent of all electrical energy consumed by industry is used by the millions of electrical motors installed worldwide. Every year, several more million motors are added. These motors are the workhorses of industry, driving machines, compressors, fans, pumps and conveyors in virtually all industrial sectors. Not only are pumps andfans numerous, they also have the greatest energy saving potential. Therefore, targeting pump and fan applications is a great way to begin with ABB energy management systems.

ABB supplies virtually every industry with a broad range of electric motors and variable frequency drives to reduce energy consumption, increase productivity and safeguard quality. Among the industries served are cement, minerals, metals, oil and gas, chemicals, pharmaceuticals, pulp and paper, water, and marine.

During the 40 years since the first variable frequency drives appeared, ABB has delivered millions of units across the globe to every type of application in all industries. During this time, vast experience has been gained of how industry can save energy in the most effective ways. The installed base of ABB drives saved 310 million megawatt-hours (MWh) in 2011, equivalent to the yearly consumption of about 75 million EU households. In terms of CO2 reduction, these savings equate to 260 million tons, more than the yearly emissions of over65 million cars.

ABB energy management systems use variable frequency drives to reduce the output of an application, such as a pump or a fan, by controlling the speed of the motor, ensuring it runs no faster than it needs. Many motors are oversized to cope with a maximum demand that rarely or never occurs. The drive brings the motor speed down to match the actual demand needed by the application.This often cuts energy consumption by 50 percent and in extreme cases by as much as 90 percent.

When other control methods are used, such as dampers, vanes or valves, the motor runs at full speed and the flow of the output is mechanically restricted. For instance, the flow through a pipeline may be reduced by a valve. This is wasteful, because the motor keeps running at its nominal speed regardless of the demand. The pump delivers maximum output and the excess is reduced at the valve, where the surplus energy is wasted through friction.The relationship between a pump or fans speed and its energy need is known as the cube law, because the demand for power increases with the cube of the speed. This means that a small increase in speed requires a lot more power,but also that a modest speed reduction can give significant energy savings. A pump or a fan running at half speed consumes only one-eighth of the power compared to one running at full speed.

In addition to the energy savings, the variable frequency drive delivers accurate control and less mechanical wear, reducing maintenance and extending the life expectancy of the system. ABB energy management systems products range from 0.18 kW to 72 MW, is the widest available from any manufacturer, offering drives for every need.Many of ABBs drives have built-in energy calculators to monitor energy consumption and savings in kilowatt hours, local currencies and carbon dioxide reductions. The drives built-in energy calculators show actual results that can be used as a basis for future energy saving projects.

To learn more about ABB energy management systems, or for ABB repair, retrofit, and replacement quotes, contact Precision Electric, Inc.


AC Electric Motors

AC electric motors operate by applying alternating current (AC) power to the electric motor. The main parts of AC electric motors are the stator and rotor. The AC electric motors’ stator consists of coils that are supplied with alternating current power and produce a rotating magnetic field. AC electric motors rotor will rotate inside the electric motor coils and the output shaft produces torque via the rotating magnetic field.

There are two different types of AC electric motors and each of them uses a different type of rotor. The first type of AC motor is called an induction motor. Induction motors use a magnetic field on the rotor of an induction motor that’s created by an induced current. The other type of AC motor is called a synchronous motor and rotates precisely at the supply frequency or on a sub-multiple of the supply frequency. Synchronous motors are able to operate with precision supply frequency because it doesn’t reply on an induced current. The magnetic field on a synchronous motor is generated by current delivered through slip rings or a permanent magnet. Synchronous motors run faster than induction motors because the speed is reduced by the slip of asynchronous motors.

AC Electric Motors With Variable FrequencyDrives

Over the past decade, AC electric motors have been paired with variable frequency drives as a cost efficient way to reduce power costs and increase system production efficiency. Approximately one third of the world’s electrical energy is supplied by electric motors in fixed-speed centrifugal pump, fan, and air compressor applications. These fixed-speed applications don’t always require the full load speed (RPM) of the electric motor in which they’re operating. By installing a variable frequencydrive to these AC electric motor applications, the motor speed is reduced, and power costs can be reduced by 50% or more.This energy savings is often significant enough to cover the cost of a variable frequency drive within a few months.

Pairing AC electric motors with variable frequency drives is common in many applications such as swimming pool pumps, air compressors, conveyor belts, lathes, mills, food processing, plastic extrusion, waste water treatment pumps, HVAC fans and blowers, and many more. AC electric motors and variable frequencydrivesare used on machinery to increase or decrease the acceleration and deceleration times on alternating current (AC) motors.

Adjusting the acceleration and deceleration time of AC electric motors can extend the motor’s lifespan, and can also improve efficiency on production demands. Variable frequency drives on AC electric motorscan also provide the ability to control the frequency of starting and stopping an AC motor.This ability provides a means by which AC electric motors are only operating when needed for the equipment they’rerotating. AC electric motors have a longer lifespan if they’re not continuously operating when they don’t need to be.

To learn more about AC Electric Motors, Variable Frequency Drives, or for Repair and Replacement Quotes, Contact Precision Electric, Inc.











Pump VFD

The BEP (Best Efficiency Point) of a centrifugal pump is dened as the operating point of highest efficiency, but also the point where velocity, and therefore pressure, is equal around the impeller and volute. The corresponding BEP for variable speed follows the Affinity laws.

Centrifugal pumps should be selected and normally operated at or near the manufacturers design specific speed for the rated conditions of head and flow best efficiency point.In a xed speed pumping application, BEP is xed. When ow modulation is required, throttling or bypassing is used. This is not the most efcient way to operate, both in energy use and mechanical stress (reliability) of the pump vfd system.

When fixed speed pumping motors are operated at reduced capacity, ie, at a flow significantly less than BEP and at a higher head, the fixed vane angles will cause eddy flowswithin the impeller, casing, and between the wear rings. The radial thrust on the rotor will increase, causing higher shaft stresses, increased shaft deflection, and potential bearing and mechanical seal problems while radial vibration and shaft axial movement will also increase. Any pump operated at excess capacity, ie, at a flow significantly greater than BEP and at a lower head, will surge and vibrate, creating potential bearing and shaft seal problems as well as requiring excessive power. Additionally, it may also infringe net positive suction head (NPSH) leading to cavitation and erosion of the impeller.

Many pump vfd systems require variable ow to meet changing process demands. The most common methods for controlling a variable ow system is a control valve, bypass line or a variable speed drive. Valve control Controlling the pump with a valve forces the pump back on the curve away from the pumps BEP, resulting in wasted energy across the valve and at the pump. In addition the pumps reliability is reduced.Bypassing the excess fluid allows the pump to operate at or near BEP, however the energy used to move the excess fluid is wasted.

Control Of Pump VFD Systems

Variable frequency drives are the most efficient method for controlling pump flow. Because the drive controls the speed of the motor directly based on actual demand, a more efficient match to the actual system requirements is more easily achieved, increased energy savings are possible, and stress on the pumping system as a whole is reduced. Variable speed operation also changes the thinking about BEP, introducing instead the pumping systems best efficiency, where the specific energy can be kept at the minimum possible value.

BEA And Pump VFD Drives

A pump vfd system’s BEA (Best Efficiency Area) considers variable speed operation and optimization of the pumping system as a whole. BEA helps to understand the benefits ofrunning pumps at variable speeds. This is achieved by using variable frequency drives to control the speed of the pumping systems motors. BEA takes hydraulic losses of the system into account, and is based on the specific energy use of the total pump vfdsystem. BEA shows the advantages of operating the pump at lower rotational speeds.

These advantages include:

  • Lower total pump system mechanical stress
  • Less stress on pump bearings, shaft and sealing system
  • Longer pump life span
  • Reduced cavitation
  • Reduced risk of pump failure
  • Good specific energy for a wide operational flow range with either single or multiple pumps

Water Hammer And Pump VFD Applications

The term water hammer comes from the pressure surges hammering effect on a system. Water hammer is also known as liquid hammer since the phenomenon can occur in other liquids. This phenomenon is the result of a rapid increase in pressure (typically in a closed loop system) when the liquid velocity is suddenly changed.

The effect of water hammer occurs due to a force applied to move and add pressure to a liquid (which is virtually incompressible) thereby creating dynamic energy that is transmitted instantly across the system. When liquid moves, stops, or changes velocity abruptly, the dynamic energy amplifies the normal system pressure creating a sudden pressure surge, or spike. When the pressure surge accelerates and approaches the speed of sound, the surge becomes an acoustic resonance with a sound wave. The pressure surge is amplified many times greater than the normal system pressure. This pressure surge can be extremely destructive to the pump, piping and valves.

In order to provide the gradual deceleration of the pump, sufcient motor torque needs to be available.Gradual deceleration of the pump speed is obtained by using a variable frequency drive with the pump vfd system.

To learn more about pump vfd systems or for pump vfd repair and replacement quotes, contact Precision Electric, Inc.


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