INTEGRATED CONTROL AND FAULT DETECTION OF AIR-HANDLING UNITS

A new method for integrated control and fault detection of central air-handling units based on finite state machine sequencing logic is described. The method evaluates thirteen residuals derived from mass and energy balances applied at specific operating conditions imposed on the air-handling unit by the sequencing logic. For faulty operation, one or more of the residuals is expected to have a value that is significantly different from zero, the expected value for normal operation. Computer simulations were used to test the method for several faults common to air-handling units.