AT-01-14-4 -- An Expert Rule Set for Fault Detection in Air-Handling Units PDF

This paper presents an expert rule set for air-handling units (AHUs) and examines the performance of the rule set using simulation and field data. APAR (air-handling unit performance assessment rules), the software implementation of the rule set, was first applied to fault-free and faulty simulation data. As expected, the ability of APAR to detect faults was influenced by the severity of the fault and the operating conditions. Results obtained through the analysis of field data with APAR demonstrated the importance of considering control performance problems. APAR successfully identified two occurrences of faults with the mixing box dampers, the first being a stuck damper and the second a manual override of a control signal that was not returned to automatic operation. The expert rule set consists of simple rules that successfully identified some fairly obvious AHU operation problems that are often hidden by compensating conditions or overlooked by operators overwhelmed by raw data.

Units: Dual