Drives and Controls Magazine
Reconfigurable windings allow motors to be used globally
Published:  16 September, 2013

The Brazilian motor-maker WEG and its Austrian subsidiary Watt Drive have developed a modular motor with a special winding design which allows the operating voltage to be reconfigured from the terminal box, allowing the same motor to be used around the world at voltages from 100–690V, and on 50 or 60Hz systems.

The modular Eusas (Europe, US and Asia) motor is available as an integral motor for gearboxes, or as a standard induction motor in two-, four- and six-pole versions with frame sizes from IEC 63–160 and power ratings from 0.12–18.5kW. Frame sizes from 180–315 will be added soon.

The motor winding is divided into two partial windings with 12 leads – providing a wide range of wiring options via a nine-bolt terminal board (shown below). This allows the motor to be wired for up to four different voltage-level configurations (Y, delta, double-Y or double-delta), making it suitable for the world market.

Until now, says WEG, induction motors have been severely limited in terms of voltage configuration options because of their winding designs. A separate motor version has been needed for each voltage level deviating from the IEC 60038 standard, resulting in extra costs and longer delivery times, especially for small quantities. The new winding design ends this limitation, resulting in a versatile, all-in-one motor.

The motors are also designed to be used with electronic speed controls. A 87/100/120Hz voltage-frequency characteristic curve allows them to be driven by frequency inverters without needing special windings. The “unique” stator winding design allows the motors to operate at double power in inverter operation, with the motor power rising to twice the nominal rating.

To let this power increase occur without overheating, the motor’s speed is doubled, leaving its torque characteristic constant. The drive operates at a higher rotational speed, allowing the higher output power to be achieved at the same magnetic flux level without overloading. The user only needs to reconfigure the winding connections on the terminal board and adjust the control parameters of the frequency inverter.

The Eusas motor is the first machine to combine WEG’s energy-efficient motor technology with the MAS modular gear system developed by Watt Drive, which WEG bought in 2011. The MAS system accepts a wide variety of motor modules and offers options such as spring-loaded brakes, encoder systems, forced ventilation and backstops. The new motors are available in foot-mounted and flange-mounted versions with a choice of standard B5, square B5 (for gearboxes) or B14 flanges.

The IP55-protected motors have class F insulation. However, the nominal temperature rise of the motor corresponds to class B. This provides a safety margin for overloads or increased winding lives. When operating at class F, the motors are suitable for ambient temperatures from –30 to +60°C.