Enhanced Prioritization – Determine if chiller is operating when OAT is below lockout temperature

Applicable Systems

  • Primary: CHLR

Description / Method

Determines if the chiller is operating when cooling plant may not be required, and calculates Potential Savings and Energy Impact. {CHLR} Compare the rolling 4 hour average outdoor air temperature to the chiller lockout temperature. Insight is triggered when Potential Savings exceeds the yearly threshold (defined by user). This can be changed to trigger on Energy Impact. Also generates PotentialSavings_DailyCUSUM ($) CTL.

  • Potential Savings is the energy cost based on time chiller is enabled below the desired OAT threshold, a forecast in $/year. The rule estimates only 26 weeks of chiller operation for a year (defined by the user)
  • Energy Impact is the number of daily hours chiller operating below threshold (expressed in percent of total daily hours chiller is on)

Logic

Enhanced Prioritization – Determine if chiller is operating when OAT is below lockout temperature
  • 1. Chiller plant operating below OAT lockout. Verify cooling plant sequence of operation.
  • 2. Automatic control has been overridden. Revert equipment back to automatic control

Message

The chiller has been operating while OAT is below its lockout temperature.
Ensure that chiller enable is not overridden, then verify the sequence of operation.

Notes

Default values for constants:

  • EnergyRate ($/kWh): 0.07
  • PotentialSavings Yearly Threshold ($): 100
  • Threshold-Weekly Energy Impact [%]: 30
  • Chiller Enable OAT Setpoint (deg): 13 degC / 46 deg F
  • Voltage 3-Phase [V] {chiller, voltage, sensor}: 480V
  • Power Factor (p.f): 0.85
  • Estimated Weeks Of Chiller Operation: 26
  • Chiller Amperage Threshold for Running [A]:0.5

Rule Template Type

  • Insight Type: Fault Detection
  • Trigger Type: Active High

Inputs

InputsUnitsDefault ValueTagsDescription
Chiller Amps {chiller,status}Amps chiller,statusAmperage TL from chiller
Outdoor Air Temp [deg] {sensor, outside, air, temp}°C or °F sensor, outside, air, tempOutdoor Air Temperature sensor TL
Voltage 3-Phase [V]Volts480 Line-to-line 3-phase voltage
Power Factor (p.f) 0.85 The suitable power factor for the site
EnergyRate [$/kWh]$/kWh0.07 Electrical utility rate
Chiller Enable OAT Setpoint [deg]°C or °F13  
Estimated Weeks Of Cooling OperationWeeks26  
PotentialSavings Yearly Threshold [$]$1000  
EnergyImpact Threshold [%]%30  

Output Calculated Trend Logs

Output CTLUnitsDescription
Chiller_PotentialSavings_DailyCUSUM[$]$Cumulative sum of daily Potential Cost Savings
Chiller_PotentialSavings_Yearly[$]$Potential Savings over a year if this problem continued for 52 weeks
Chiller_EnergyImpact_Weekly[%]%Weekly Energy Impact
HrsOperatingBelowThreshold_DailyHoursNumber of hours the chiller has been operating below OAT threshold