ET23SWE0065 - Central HVAC Advanced Electric Motor Lab Evaluation
Implementing more efficient electric motors can greatly reduce the amount of energy used, save money, and reduce greenhouse gas emissions. Many new electric motor technologies promise higher efficiency, particularly in variable speed applications. However, end-users are reluctant to switch from their old technologies, either due to the upfront cost or they are not interested in trying a less familiar product due to potential for issues with incompatibility, controls, and unknowns such as reliability and expected life.
In recent lab dynamometer testing at the UC Davis Western Cooling Efficiency Center the ABB Baldor-Reliance® EC Titanium™ motor had the highest efficiency across a range motor speed and torque. The Baldor EC Titanium combines synchronous reluctance and permanent magnet motor technologies (PMSynRM) and is commercially available from a widely trusted manufacturer. Our search has not been able to find any case studies for this PMSynRM advanced motor type.
The Western Cooling Efficiency Center at UC Davis will install variable speed high efficiency PMSynRM motors in the water loop pumps that supply HVAC cooling and heating water for a UC Davis campus office building. Each advanced PMSynRM motor will be paired with the standard practice variable speed NEEMA premium rated induction motors operating in parallel. The advanced motor and standard motor will operate in parallel at the same time and same speed on the same water loop return water manifold and supply water manifold and will use the same make and model of variable frequency drive to allow for a direct comparison of efficiency. The power consumption of both the advanced motors and standard motors will be monitored to evaluate energy savings and estimate typical operating cost savings. The installation process will be documented to identify any differences from the standard motors and identify solutions to any issues that occur to inform future energy efficiency program design.
The Western Cooling Efficiency Center at the University of California, Davis, completed a field evaluation of advanced electric motor technology in hydronic pumping for the variable air volume HVAC system of a three-story, 47,459-square-foot office building constructed in 1998. The study compared the performance of ferrite-assisted synchronous reluctance motors, a type of permanent magnet-assisted synchronous reluctance motor, against the commonly used National Electrical Manufacturers Association premium induction motors. New motors, variable frequency drives, and pump heads of both the upgrade and baseline types were installed side by side in a variable speed pumping application for heating hot water and chilled water.
The advanced motors were compatible with standard pump mounts and required minimal changes to installation procedures or building energy management controls. Electricians noted minor differences in VFD setup, but no additional training or tools were needed.
On the heating hot water system, the ferrite-assisted synchronous reluctance motor reduced measured energy use by 18 percent, with an expected simple payback of 0.34 years for motor additional equipment cost only, or 3.3 years including the full equipment cost of a new variable frequency drive, assuming $0.39/kWh tariff. Calculating the baseline motor energy consumption to correct for asynchronous motor slip increases the predicted energy savings to 28 percent for a simple payback of 0.25 years for motor equipment cost premium or 2.4 years including the full equipment cost of a new VFD.
On the chilled water system, the ferrite-assisted synchronous reluctance motor reduced measured energy use by 17.9 percent, with a simple payback of 2 years for motor additional equipment cost only, or 5 years including the full equipment cost of a new VFD. Adjusted to correct for baseline motor slip, the savings are 18.9 percent with a simple payback of 1.3 years for the motor equipment cost premium; adding the full equipment cost of a new VFD, the simple payback would be 4.4 years.
This study demonstrates that ferrite-assisted synchronous reluctance motors can deliver meaningful energy savings in hydronic HVAC systems with minimal changes to standard retrofit practices. The results of this project support further deployment of this technology and provide a foundation for utility program development, a comparison for future energy savings simulation estimates, and are a resource for contractor training.
