In industry, electric motors are often used in applications with numerous braking processes. A brake chopper and external electrical resistors dissipate braking energy in the form of heat. This then dissipates ineffectively or even has to be cooled with additional energy. Regenerative speed-controlled drives, on the other hand, can feed this braking energy back into the grid. This significantly improves energy efficiency.

The regenerative frequency inverters ABB Industrial Drives ACS880 cover a power range from four to 3,200 kilowatts. They can significantly reduce energy consumption, reduce space requirements by up to 85 percent thanks to their compact design and thus also reduce investment costs by up to 30 percent, ABB calculates. In addition, the lower heat dissipation means that less expensive air conditioning is required in the electrical room. Recovered energy is "clean" and of high quality. It can be used by other consumers, which increases system efficiency. The new generation of ABB Industrial Drives can regulate the cosine phi of the fundamental oscillation to unity under all load conditions, so that reactive power and energy consumption are optimized.

An example shows how much energy such solutions save: for a crane for waste disposal with a 55-kilowatt hoist motor, a nine-kilowatt crane travel motor and a 4.5-kilowatt trolley travel motor and a regenerative frequency converter, the savings per year amount to an estimated 15.6 megawatt hours of energy - or the equivalent of around 2,300 euros. This 32 percent reduction corresponds to the average annual energy consumption of four German households.

The ACS880 regenerative frequency inverters feed braking energy from electric motors back into the grid as an almost harmonic-free current. (Image: ABB)

Removing interfering harmonics
Non-linear electrical loads, including speed-controlled drives, cause harmonics that lead to undesirable distortions of the voltage and current in the grids. The harmonics lead to unreliable operation and can overheat other loads such as motors, transformers and other electrical equipment. This requires additional cooling, causes energy losses and, in the worst case, can lead to premature failures. Although additional electrical filters can dampen these harmonics, it is better to prevent them from occurring in the first place. This is exactly what the new generation of regenerative ABB frequency inverters does, preventing harmonics before they occur.

Less downtime thanks to greater reliability
The ACS880 regenerative frequency inverters are characterized by high immunity to mains interference and can keep the motor voltage stable or even increase it even when the supply voltage is unstable. This ensures reliable operation even if the feed-in voltage drops below the normal value.

Braking energy recovery: The area marked in green is a measure of how much energy can be fed back into the grid. (Image: ABB)

By eliminating external brake components, ABB's regenerative frequency inverters can be built more compactly than conventional solutions. The resulting reduction in engineering and material costs and the smaller space requirement in the electrical room mean potential savings in cabinet construction costs. The ACS880-11 wall-mounted units, the ACS880-14 built-in modules and the ACS880-17 enclosure units have all the necessary components integrated in a ready-to-connect housing. This makes cabinet installation even easier and quicker, as there is no need for subsequent wiring of various components.

The ACS880 ensures full motor voltage under all conditions. The frequency inverters are equipped with DTC torque control and offer precise and dynamic speed and torque control for maximum motor performance and efficiency.

This means that these ABB solutions can meet even the highest demands, such as those required for applications on test benches. An ABB Industrial Drive ensures not only the necessary precision but also significant cost savings on the all-wheel drive test bench of a leading agricultural machinery manufacturer. Up to 90 percent of the braking energy that was previously converted into ineffective heat during the tests can now be recovered thanks to the ABB frequency inverter. Similar effects can also be achieved in other typical applications such as centrifuges, balancing stands, winders or turbines.

Digitalization and connectivity

The ACS880 also serves as a multiple sensor that reads out important information such as motor speed, motor torque, motor currents, various temperatures and many other parameters. This data is then available for diagnostics, remote monitoring and process optimization via ABB Ability - the bundling of all products, services and solutions in ABB's digital offering, including cloud connection. pb

Hall 11, Stand A35