WEG Electric Motors

Saying that thanks to its robustness and reliability, the standard 3-phase squirrel cage design of electric motor has been around for over a century, despite probably achieving its optimum levels of performance, WEG Electric Motors has introduced Wmagnet series of permanent magnet (PM) motors, as a viable alternative. WEG, supplier of electric motors and related control equipment, said that the new motors have been designed for applications where constant torque, Iow vibration and low noise levels are required.

The manufacturer claims that the Wmagnet series can be used in elevators, compressors and conveyors. Because they can operate self-ventilated over a wide speed range, the motors are also ideal for use in applications where gearboxes need to be eliminated to save space, it adds.

It lists the following product features and advantages:

The WMagnet motors reduce size by up to 50%, weight by up to 36%, and deliver higher efficiencies (up to 97.5%) compared to equivalent size induction motors.

They are, generally, at least one frame size or core length smaller than the equivalent induction motor, and in some cases, can be two frame sizes smaller. Therefore, the cooling system is reduced for the same torque/power ratio, and consequently, there is a reduction in the levels of noise from the fan coupled to the motor shaft.

They are manufactured with high energy magnets (NdFeB) in their rotors. These deliver a significant reduction in energy losses compared to an induction motor, resulting in a lower temperature rise of the motor and increased operating life.

As these energy (Joule) losses (RI2) account for a significant portion of total losses in induction motors, the PM motor delivers much higher efficiencies (up to 97.5%), exceeding the new harmonised IE (International Efficiency) standards: IE2, which comes into force in July 2011, IE3, and also, attains IE4.

It can operate on a wide speed range (up to 7,300 rpm in special cases) with constant torque. This is controlled by a version of WEG’s CFWO9 VFD, which has been specially developed for the Wmagnet range. The CFW09 employs its vector control technology to effectively drive the WMagnet from zero speed up to the field weakening region.

According to WEG, in one of the first field applications for the WMagnet motors, Buettner, a Brazil-based textile manufacturer, purchased three WMagnet motors from WEG, and has been able to reduce its annual power consumption by 33% and increase its machine utilisation by 80%. These twin gains have delivered substantial savings in production costs and have also improved the company’s profitability in a highly competitive global market, WEG claims.

It quoted Aires Fantoni, Electrical Maintenance Supervisor at Buettner: “Our goal is to replace all of our standard induction machines with WEG WMagnet motors within three years.”

Marek Lukaszczyk, European Marketing Manager for WEG added, “As demonstrated by the Buettner application, the WMagnet motors are ideal for applications where eliminating a gearbox is essential; the motors can do this because they can operated self-ventilated over a wide speed range.”