Determine if cooling tower bypass valve operation is faulty

Applicable Systems

• Primary: CHLR

Objective/Method/Outcome

• Objective: Determine whether the cooling tower bypass valve is operating properly.

• Method: Bypass valve is considered faulty when it is fully open (100%) and the Cooling Tower Flow is above the minimum (100GPM).

• Outcome: An insight is generated if this condition has occurred for more than 4 hours this week.

Logic

Normalize all inputs to 15-minute intervals. When the bypass valve is fully open (100%) and the flow is greater than the minimum, calculate “fault” time. Sum this over the week. Store in CTL. Trigger insight if the sum is over the threshold. Also, store Bypass Valve Position Hourly Average and Cooling Tower Flow Hourly Average.

sum hours over the week{
   if (flow greater than minimum and bypass valve is on, time, 0)
   }
if(sum> threshold , Insight,  no_insight)

Notes

The rule generates two Calculated Trend Logs (Bypass Valve Position Hourly Average, and Cooling Tower Flow Hourly Average).

Inputs

Inputs	Units	Tags	Description
CHWS Enable	0/1	enable	cmd,cool,water,system	Equipment On/Off Indicator
Flow	GPM	tower,flow,sensor	Cooling Tower Flow
Bypass valve Position	%	bypass,valve,cmd	feedback	Bypass Valve

Parameters

Inputs	Units	Default Value	Description
Weekly Threshold	hours	4	Allowable time for bypass valve to be open and cooling tower flow greater than minimum

Calculated Trend Logs

Output CTL	Units	Frequency	Description
Bypass Valve Position Hourly Average	%	hourly	Bypass Valve Position Hourly Average
Cooling Tower Flow Hourly Average	GPM	hourly	Cooling Tower Flow Hourly Average