Mitsubishi has announced a range of drives with integrated regenerative braking which, it claims, will need up to 60% less main circuit wiring and occupy up to 40% less space than conventional drives. As well as conserving energy in high-torque applications such as lifts and conveyors, the FR-A741 drives (developed from the FR-A700 range), are said to cut drive system costs and to allow simpler, more compact switchgear layouts.

The drives are designed to address three key problems with drive systems in high-power, high-torque applications – power consumption, size and heat generation.

The regenerative system enables the drive to feed braking energy back into the power grid with minimum losses, reducing power consumption and operating costs. The technology generates less heat than braking resistors, in turn reducing the need for space and for additional cooling mechanisms.

Mitsubishi says that the regenerative inverters will usually pay for themselves within months, even in some applications with low power requirements and standard motors. It cites the example of a 22kW drive in a shelf access application which, in the case of a conventional installation with braking and an AC reactor, would cost €12,839 to install and run for a year. An equivalent system based on an FR-A741 inverter would cost € 8,840 in the first year, representing a saving of 32%, with further savings in subsequent years.

The new range consists of ten inverters in the power range 5.5–55kW. They are said to be ideal for tasks involving frequent cyclical acceleration and deceleration, and for applications where braking resistors are normally used. Harmonic interference is suppressed by integrated AC reactors, with the option of further harmonic suppression if needed.