Posted to News on 11th May 2011, 13:20
MF three-phase motors save space, energy and cost
Lenze is promoting its innovative L-force MF three-phase motors that are designed for use with frequency inverters. Increased power means that MF inverter-optimised motors can be up to two frame sizes smaller than conventional asynchronous motors with the same rated power. Over a power range from 0.55 to 22kW, MF motors deliver efficiency levels better than IE2 and they take away worries about compliance with the ErP regulations.
The higher rated speeds of the MF motors, around 3400 to 3500rpm according to size, leads to higher power ratings. A frame size 71 is sufficient for 1.5kW where a conventional three-phase four-pole motor would be 90 frame, resulting in smaller drive footprints. Another advantage is the speed setting range across which constant torque is available; at 1:24, this is about twice as good as the alternative. Furthermore, the higher speeds lead to increased efficiency, contributing to the efficiency figures better than IE2 levels.
In many cases the MF motors are supplied as part of a geared motor assembly. Usage is increasing in areas such as retrieval and storage units, and machine feeds, where the smaller sizes and lower inertias permit more dynamic operation. Lenze offers a range of in-line and right-angle gearboxes with correspondingly higher ratios to compensate for the increased motor speed. In most cases the reduction is possible without an additional gearbox stage, as the input pinion is a part of the motor shaft, thereby achieving high ratios in small dimensions.
MF motors are complemented by the Lenze 8400 series frequency inverters. These are available for both central panel mounting and decentralised control with an IP65 protected variant. This second option can be mounted in the motor terminal box position or on a wall nearby. Particularly in applications with partial loads, new VFCeco software, which is supplied as standard with the 8400 inverters, can give further energy savings of up to 30 per cent.
The new MF motors offer significant savings compared to standard four-pole motors in a power range of 0.55 to 22kW. Their smaller size helps machine construction and gives more dynamic performance. They are energy-efficient and the savings can be enhanced by VFCeco software in the matching 8400 inverter range. In many cases they are actually lower in cost than a four-pole standard motor of the same power. Follow the link for more information and a brochure describing the L-force MF inverter-optimised motors.
