Contact

Home

All WEG Motors have Enlarged Grease Cavities and Double Strength End Bearing Retainer Caps to ensure proper lubrication.
 

All Crusher Duty WEG Motors have Cast Iron Frames - Junction Boxes are made with Extra Strength Cast Iron Density (FC200).

News Release from: WEG Electric Motors Edited by the engineering talk Editorial Team on August 1, 2003

Motor friendly inverters are is the key to avoiding problems in AC motor/drive systems, says Graham Perry, Product Manager for AC Drives at WEG. The negative effects that inverters can have on AC motors is a relatively new subject, which explains why only a few motor manufacturers have reacted and why many others are still building motors using materials and technology that are unsuitable for today's market demands. This is short sighted in terms of long-term sales prospects, as experience shows that in some cases, where voltage spikesresulting from the inverter carrier frequency are severe, motor life can be reduced considerably. A general rule for avoiding this problem is to select inverters with reduced harmonic content, and harness them to new technology motors, such as WEG W21 Line, which offer high dielectric strengthin their motor windings as a result of enhanced insulation and low and homogenized internal temperature.

 

The AC motor is, of course, only one part of the overall drive system, and while protecting it against negative inverter effects is essential, other measures should also be considered; making the inverter "motor friendly" in the first instance, for example. This is exactly what WEG has done with its new CFW-08 and CFW-09 ranges of vector based drives. The new WEG drives have been designed as an actual complement to WEG motors, and are also eminently suitable for use with other high efficiency brands on the market. The drives cater for OEM and user requirements at both the low end and high ends of the control market, offering high levels of functionality at competitive cost across the power range from 0.25 to 700kW. 

The motor friendly credentials of the WEG CFW-08 and WEG CFW-09 drives are based on exhaustive tests carried out at WEG headquarters. These tests allied WEG's own, and other manufacturers' ranges of drives, with WEG W21 Line of high-efficiency motors. The only variable in the tests was the make of drive, all other conditions being maintained the same.  The first area to be tested across the ranges of drives was motor temperature increase (delta T). This revealed that the delta T of the motor was up to 11% lower using WEG drives, when compared with the other VSDs tested. This is important for motor longevity, because when motor operating temperature is lower, the benefit is a longer insulation life. 

 

The WEG motor package (motor plus WEG VSD) also proved to have lower noise levels across the range of motor operating frequencies (in some cases the noise was up to 9% lower) compared with some other drives at the same conditions of load, switching frequency and motor operating frequency. The lower noise is a result of the WEG space vector modulation (SVM) technology used in WEG VSD, which generates optimized PWM waveforms. SVM also reduces the motor losses related to harmonics, leading to lower motor temperatures and increasing motor life.

Increasing the efficiency of SVM is an "online" dead time compensation function, which corrects the PWM pulses, optimizing the waveforms generated for the WEG motor.
 

This technique reduces the torque ripple at low speeds and provides smooth motor operation at no load or light load conditions, avoiding motor speed and current oscillations. The many operating benefits provided by SVM technology were also evident in the overall total efficiency tests conducted by WEG. The combined effects of WEG SVM gave the package of the WEG motor and WEG VSD the highest total efficiency, at around 97%, of all the drives tested.

This efficiency level can be maintained even when eccentric load applications are encountered.
 

The CFW-09 has a specific function for eccentric loads, which optimizes motor operation and efficiency, leading to significant energy savings. Usually in eccentric loads the load pushes the rotor speed higher than the synchronous speed, pumping energy to the DC link. This energy should be burned in a resistor (dynamic braking) to avoid drive over voltagetrips. The referred function manages to increase the speed in this situation avoiding over voltage trips while also saving energy.

 

Two other major areas where WEG VSD take the strain from the motor are braking and load reactance. In the former area, the WEG CFW-09 architecture includes a novel "optimal braking" feature for applications that requires reduced braking times or the stopping of high inertia loads.
 

Traditionally, conventional variable speed driveshave relied on dynamic brakingresistors to dissipate excessive heat regenerated in their DC links under braking. In contrast, optimal braking provides sufficient braking performance to eliminate the need for the resistor in the majority of applications. This results not only in cost savings but also enables highly dynamic performance in drive systems with braking torques of about five times that of typical DC braking systems.

 

The final area of motor care, load reactance, is a direct result of WEG experience as a world-class supplier of electric motors. Load reactance is the result of a mismatching of motor cable impedance and motor impedance, leading to a rapid voltage rise that can easily cause damage to motor insulation, especially in low-cost motors. WEG Motors are not subject to this problem as their insulation system is designed specifically for use with VSD. However, to cater for motors that are not so well insulated, WEG Electric Motor has ensured that the turn on time of the output devices in its new drives is set at a level that reduces voltage rise time. As this feature is internal to the drive, no additional external output chokes or special output filters are required, ensuring that greater motor reliability is not bought at the expense of additional cost.

 

 

 

 

WEG Motors and VSD variable speed drives may be purchased at:

 

Weg Electrical Motors

Manufacturers Distributor

Phone: 800-761-4298

Facsimile: 800-977-1634

Email: sales@WegElectricalMotors.com