Motors make gains in energy efficiency, process reliability

Motor manufacturers are finding ways to improve the performance of their motors.

Monitoring data generated by Siemens motors can help plant maintenance teams improve operating performance.
Monitoring data generated by Siemens motors can help plant maintenance teams improve operating performance.

Energy makes up 80 percent of the cost of owning and operating a motor over its lifespan. That’s why motor makers have spent decades trying to build ever more energy-efficient designs. But with standard motors already achieving 96.7 percent efficiency, current technology might be reaching its limits.

Some motor manufacturers say it’s impractical to continue making significant design investments in motors if the resulting price increases will outweigh any small efficiency gains. Others are turning to tools, both old and new, that can give motors a helping hand.

Efficient at varying speeds or loads

No matter how efficient a standard induction motor is rated, most users realize that actual energy performance can vary greatly depending on the application. “An induction motor’s efficiency decreases as speed and/or load is reduced,” explains Oscar Palafox, product and R&D manager for Siemens low-voltage motors.

HVAC systems, whose operating requirements vary depending on whether it’s day or night, or production lines where load and speed change frequently, are two typical applications where the efficiency delivered could be less than what the rating promises.

To deal with these situations, Siemens has introduced synchronous reluctance motors, which the company says can reduce energy usage by up to 70 percent. “At 100 percent speed and load, synchronous reluctance motors are slightly more efficient than induction motors,” Palafox says. “But because they maintain that high efficiency through most of the speed range, they achieve substantially better results in variable-speed applications.”

The motors fill a gap between standard induction motors and more expensive permanent magnet motors, according to Rich Mintz, Siemens’ marketing manager for large motors. Synchronous reluctance motors work in tandem with a variable-frequency drive to achieve the most efficient drive train performance.

“You need to look at the entire drive system for efficiencies, rather than just a single component,” Mintz adds. “If motors are inexpensive, people don’t think they need to monitor them. But you need to look at the bigger picture. It’s not just the cost of a motor; it’s the cost of unplanned downtime that you have to calculate.”

This trend toward measuring the efficiency of the entire system, which began in Europe, starts with the motor and drive, but extends out to the driven equipment. While typical efficiency standards for motors calculate efficiency at a fixed speed and load, the European standard provides ways to determine the efficiency of a system at various speed and load values.

Data produced by the drive system can be a powerful tool for optimizing machine performance. “Digital simulation tests allow you to understand the implications of equipment performance changes,” Mintz says. “By creating a digital twin of what’s working on the factory floor, you can determine how motors will react to variations in their operating conditions. This can teach you how to improve the system before actually making any physical changes.”

Digitalization is the foundation for the Industrial Internet of Things (IIoT), a trend with the potential to change how equipment and their motors are monitored and operated. “By installing a digital backbone,” says Ryan Maynus, product manager for Siemens medium-voltage motors, “companies can gain real-time visibility into machine health and the small variations that, over time, can have a big impact on uptime, productivity, safety and other performance factors.”

To help with this effort, Siemens has created MindSphere, a cloud platform for industry that provides a secure environment for data analytics and connectivity capabilities, tools for developers, applications and services. It is designed to help evaluate and use data to gain insights that can drive asset performance and optimization.

Seeking IE4 efficiencies

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