Energy Systems Laboratory (http://esl.eslwin.tamu.edu)
Abstract
Increased interest in optimal control, energy scorekeeping and
fault detection for HVAC equipment in commercial buildings has
focused attention on instrumentation required to obtain the
desired data. In this paper we investigate what can be learned
from measurements of electrical power at a single point, that of
the electrical service for the entire HVAC system. This low-cost
measurement has proved in field tests to be capable of detecting
the power change when a piece of equipment turns on or off;
detecting oscillating equipment power caused by poorly tuned
controllers; and detecting suboptimal staging of multiple chillers.
Detection of equipment start and stop transitions was
strengthened by application of a nonlinear filter that determines
the point of median power from a filtering window of user-selected
width.
A review of electric motor literature indicated that samples of
electrical current taken at slightly faster than twice the 60 Hz
fundamental can be used to detect several indicators of incipient
motor failure. Tests were initiated to determine whether this
technique can be applied to a number of motors on the same
circuit
