YE4 Series (IE4) IEC Frame 355 Three-Phase Motor

Although IE4 motors typically carry a 15% to 30% higher purchase price, electricity accounts for over 95% of a motor’s total lifecycle cost. Because IE4 improves efficiency by an additional 1.5% to 3%, facilities running high-load equipment—such as industrial pumps, fans, or compressors—for over 6,000 hours annually can generally expect to recoup the price difference through energy savings within 12 to 24 months, with even faster returns in regions with higher utility rates.

In most cases, these are “drop-in” replacements because our IE4 motors are designed strictly according to IEC standards for frame sizes, center heights, and shaft diameters to match existing IE2 or IE3 installations. However, because reaching IE4 efficiency often requires more internal material (such as additional silicon steel or copper), the overall length of the motor may be slightly longer and the unit somewhat heavier, so we recommend verifying the external clearance in exceptionally cramped spaces before installation.

High efficiency directly translates to lower internal heat loss, meaning IE4 motors typically operate at temperatures 10°C to 15°C cooler than lower-efficiency models. This reduction in thermal stress significantly slows the degradation of bearing grease and winding insulation, which extends the overall service life, reduces the risk of unplanned downtime, and lowers long-term maintenance costs—factors that are critical for 24/7 continuous manufacturing environments.

If the installed motor is a standard IEC metric frame 355 with the same mounting and shaft, YE4 Series (IE4) is designed as a dimensional replacement. Always match kW, poles, voltage, and duty.