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Energy recovery system ‘can pay for itself in a year’

17 May, 2016

The German automation developer Lenze has unveiled a system for recovering braking energy, which separates the supply and recovery paths, allowing them to be designed and dimensioned individually for an application. The Smart Energy Recovery r700 modules have a claimed conversion efficiency of 98% and Lenze says that, depending on the amount of energy recovered, they can pay for themselves in around a year.

Conventional energy recovery systems are often not economic, because they are difficult to install and operate, and their costs far outweigh any savings. Lenze says that its new modules make energy recovery feasible, even in applications that would previously have been regarded as uneconomic.

The system comes in two power ratings: 12kW (continuous) /24kW (peak) and 26/48kW.

The recovery circuit is connected to an intermediate circuit of an appropriate size which, in turn, feeds regenerative power into the supply grid via a separate rectifier. The regenerative function is designed so that power is returned to the grid only when there is too much power in the intermediate circuit.

By decoupling the power supply and recovery paths, the frequency inverter’s uncontrolled bridge rectifier remains unchanged and the recovery circuit and EMC measures can be chosen to suit the regenerative power required. No external filter components are needed, making the device much smaller than conventional systems.

Lenze's says that its new energy recovery system takes the technology to new levels of efficiency, practicality and simplicity

The regenerative power can be scaled simply by connecting several modules in parallel. Users do not need to adjust the modules or to set any parameters before deployment. Retrofitting to existing machinery is said to be easy.

One typical application is lifting and handling equipment where a relatively large amount of energy is accumulated as the load is lowered. Another is test benches where test-piece energy needs to be discharged. In applications of this type, it is not possible to convert braking energy into heat or to store it in the system, so recovering the generated energy and feeding it back into the grid via the new modules is a real alternative, according to Lenze.

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