New regenerative inverter cuts energy and installation costs

The new FR-A741 inverter range from Mitsubishi Electric has an integrated Regeneration braking function that conserves energy and reduces costs in high torque applications such as hoists, lifts, winders, conveyors, testing machines and centrifugal separators. The regeneration function also makes it possible to achieve smaller, less expensive drive systems and simpler more compact switchgear layouts, saving both cabinet space and cost.

Photo by Mitsubishi Electric Europe B.V.

The FR-A741 effectively addresses the three main problem areas with motor drive systems in high torque/high power applications. First; that they usually account for the largest share of total power consumption. Second; that they take up a lot of space. Third; that they have significant heat dissipation requirements.

 The power regeneration system integrated into the FR-A741 inverter enables the drive to feed back regenerative braking energy into the power grid with minimum losses. This energy can then be used for other purposes, reducing overall power consumption and operating costs substantially. In addition, regeneration technology generates less heat than that produced by conventional braking resistors, which in turn reduces space requirements – and also power consumption, as no additional cooling devices are required.
What the above savings mean in real-world quantitative terms, is that drive solutions using FR-A741 inverters require up to 60% less main circuit wiring, and occupy up to 40% less space than conventional solutions, depending on the output capacity of the frequency inverter.

These economies, combined with the drive’s considerable energy saving capabilities, provide the major benefit of a substantially reduced total cost of ownership (TCO) for users of the FR-A741 range.

 The efficiencies that combine to produce reduced TCO also mean that the FR-A741 inverter can usually pay for itself within months – even in some applications with lower power requirements and standard motors. For example, in a Shelf Access System drive application the hardware investment and energy costs of a conventional 22- kW inverter, with a braking unit, braking resistor and AC reactor, amounted to € 12,839 per year. In comparison, the FR-A741  power inverter with power regeneration cost just € 8,840 per year, including the purchase price of the inverter itself. This represents a saving of 32 % in the first year alone, which is further compounded by additional high savings in power costs in the following years.

 The FR-A741 has been developed from Mitsubishi Electric’s well-proven and highly reliable FR-A700. As such, it has all the features users expect from a high-end drive, including simple operation and maintenance, operating time monitoring, network support, eco- friendliness, and long-life components that enable the FR-A741 to be specified for a 10-year service life.

 Apart from operating efficiency and reliability, another major benefit of the innovative features built into the FR-A741 is that they enable the drive to be integrated easily into complex applications. To illustrate this; special crane programming functions are supported for easy integration into hoisting applications, including a special external brake control sequence, functions for load-based speed switching, and four inde-pendent torque thresholds for all four quadrants.

 Although a high-end drive, the FR-A741 has no special requirements, in respect of power supply disturbances, beyond those of standard frequency inverters.

 Harmonic mains interference is efficiently suppressed by an integrated AC reactor; and there is also an additional harmonics suppression option available to further minimize network interference.

 The FR-A741 range currently includes 10 inverters in the power range from 5.5kW to 55kW. All of these units are particularly well suited for tasks involving frequent cyclical acceleration and deceleration, and applications where braking resistors are normally used. They offer full output capacity- without restrictions – up to an operating frequency of 14.5 kHz.

 Conforming to international standards, the FR-A741 inverter range can be used with confidence by exporting OEMs, as well as in-house drive users. All inverters in the range bear the CE mark, have UL, cUL and GOST certifications, and meet all the requirements of the EU’s 73/23/EEC Low Voltage Directive and 98/37/EC Machinery Directive.