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 $/year. The rule estimates only 26 weeks of chiller operation for a year (defined by the user)
- Energy Impact is the number of daily hours chiller operating below threshold (expressed in percent of total daily hours chiller is on)
Logic
Diagnosis / Recommended Action
- 1. Chiller plant operating below OAT lockout. Verify cooling plant sequence of operation.
- 2. Automatic control has been overridden. Revert equipment back to automatic control
Message
The chiller has been operating while OAT is below its lockout temperature.
Ensure that chiller enable is not overridden, then verify the sequence of operation.
Notes
Default values for constants:
- EnergyRate ($/kWh): 0.07
- PotentialSavings Yearly Threshold ($): 100
- Threshold-Weekly Energy Impact [%]: 30
- Chiller Enable OAT Setpoint (deg): 13 degC / 46 deg F
- Voltage 3-Phase [V] {chiller, voltage, sensor}: 480V
- Power Factor (p.f): 0.85
- Estimated Weeks Of Chiller Operation: 26
- Chiller Amperage Threshold for Running [A]:0.5
Rule Template Type
- Insight Type: Fault Detection
- Trigger Type: Active High
Inputs
| Inputs | Units | Default Value | Tags | Description |
|---|---|---|---|---|
| Chiller Amps {chiller,status} | Amps | chiller,status | Amperage TL from chiller | |
| Outdoor Air Temp [deg] {sensor, outside, air, temp} | °C or °F | sensor, outside, air, temp | Outdoor Air Temperature sensor TL | |
| Voltage 3-Phase [V] | Volts | 480 | Line-to-line 3-phase voltage | |
| Power Factor (p.f) | 0.85 | The suitable power factor for the site | ||
| EnergyRate [$/kWh] | $/kWh | 0.07 | Electrical utility rate | |
| Chiller Enable OAT Setpoint [deg] | °C or °F | 13 | ||
| Estimated Weeks Of Cooling Operation | Weeks | 26 | ||
| PotentialSavings Yearly Threshold [$] | $ | 1000 | ||
| EnergyImpact Threshold [%] | % | 30 |
Output Calculated Trend Logs
| Output CTL | Units | Description |
|---|---|---|
| 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_Daily | Hours | Number of hours the chiller has been operating below OAT threshold |