A new preventive maintenance program at a leading New England Ivy League university demonstrates how the push for more sustainable green building management has led to a growing awareness of a chronic, widespread problem with HVAC motors – electrical bearing damage and failure.
One of the maintenance department’s most significant efforts to foster sustainability at the more than 300 buildings it services is a testing program for HVAC motors controlled by variable frequency drives (VFDs). Many of the buildings have their own maintenance managers. Whenever such a manager requests testing on a motor in his/her building, technicians from maintenance headquarters use portable oscilloscopes and voltage measuring probes to determine whether or not shaft voltages are present – voltages which cause electrical discharges through the motor’s bearings.
The group tested two motors in a variety of conditions that generated static discharge, among other things. They examined bearing damage as well as other problems that came up during the testing.
Operations and maintenance costs are often 60-80 percent of the total life-cycle costs of a building. With equipment that does not have to be repaired or replaced as often, that percentage will drop. Energy-saving technology must be sustainable to help reduce these costs. In the case of VFDs, to “bank” cost savings from their reduced energy usage, users must protect the bearings of motors controlled by the VFDs with proven long-term, maintenance-free shaft grounding.
The university’s maintenance department estimates that several hundred motors campus-wide could benefit from this technology, and they are hoping the test results will entice individual building managers to contact the department for an evaluation. In keeping with its green mandate, the department is aggressively promoting bearing-protection rings as a way of realizing the full energy and cost-saving potential of VFDs.
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