Determine chiller temperature performance KPI score

Applicable Systems

• Primary: CHLR

Objective/Method/Outcome

• Objective: Determine chiller temperature performance score

• Method: Analyze the chilled water supply temperature (CHWST) control system using the amount of time the chilled water supply temperature is within deadband while the chiller is on.

• Outcome: A KPI score is generated on a daily basis while a ‘Bad Score’ insight can be produced weekly when a score reaches below 60% for the week.

Logic

• Input normalized water temperature and its corresponding temperature set points.
• With a temperature deadband constant, check if the deviation is out of range.
• If deadband is exceeded and the chiller is active, pass a bad score. If within deadband and the chiller is active, pass a good score.
• Aggregate and average score daily and weekly; generate the daily KPI score in a CTL.
• If the weekly score is below an acceptable threshold, generate an insight.

while(chlr sts == 1)
   {
   if( |CHWST - CHWST SP| > Deadband Const. )
         {
         Award performance KPI score 0%
         }
   else
         {
         Award performance KPI score 100%
         }
   average performance KPI score daily
   average performance KPI score weekly
   }

Description / Method

Determine the performance index of a chilled water supply temperature (CHWST) control system using the amount of time the chilled water supply temperature is within deadband (SP ± 1.5) while the chiller is on. {CHLR}

Diagnosis / Recommended Action

1. Issue with control loop. Review and modify controller tuning parameters.
2. Chilling water not available. Verify Chiller plant operation.
3. Automatic setpoint control has been overridden. Revert setpoint back to automatic control.
4. Input sensor(s) faulty or miscalibrated. Verify input sensor(s) operation.

Message

The chiller’s temperature performance KPI score is below 60% for the week. Review control loop tuning parameters.

Notes

This rule will not generate an insight unless the user changes the Trigger Block to “Insight – Bad Score”.
This rule is designed for °C inputs by default.Default Constants:

• Const. – Acceptable Weekly Score [%]: 60
• Const. – Chilled Water Supply Deadband [°C]: 1.5
  • (Recommended default Deadband for Fahrenheit is 3 °F)

CTL Generated:

• CHWST Performance KPI

Rule Template Type

• Insight Type: Integrity KPI
• Trigger Type: Active High

Default Priority

Low

Inputs

Inputs	Units	Default Value	Tags	Description
Chilled Water Supply Temperature	°C		sensor, leaving, chilled, water , temp	Chiller water supply temperature from chiller
Chilled Water Supply Temperature Setpoint	°C		sp, leaving, chilled, water, temp	Chiller water supply temperature set point
Chiller Status			cmd|sts	Chiller status
Const. – Chilled Water Supply Temperature Deadband	°C	1.5		The acceptable temperature deviation from setpoint
Const. – Acceptable Weekly Score	%	60		The lowest acceptable weekly KPI score

Output Calculated Trend Logs

Output CTL	Units	Description
CHWST Performance KPI	%	Daily generated performance KPI score