NIST APAR28 – Mode of operation changing state too frequently (Mode Changes)

Applicable Systems

  • NISTAPAR: APAR28
  • Primary: AHU, RTU, MUA, ERV

Objective/Method/Outcome

  • Objective: ndicates that the AHU mode of operation state is changing too rapidly.
  • Method: Counts the number of chenges in modes of operation per hour.
  • Outcome: An insight is generated when the number of changes in modes of operation is more than 3 times per hour.

Logic

 If (Mode changes per Hour > Max number of changes) { return true; }
NIST APAR28 – Mode of operation changing state too frequently (Mode Changes)

Inputs

  • AHU_MODE_CTL {ahu, mode} (Real Trend Log)

Parameters

Parameter Expression Block Series Number Description Default Value (Units)
Parameter Expression Block Series Number Description Default Value (Units)
Max number of changes allowed per hour 4 The amount of number of changes allowable for the unit per hour. Anything more than that time is considered a fault. 12 (h)