1. ## Honeywell XL15C Pump Lead Lag and Cooling Tower Control

In a week or so I have to program a XL15C for a rotating lead lag sequence for the pumps. I also have to set up a cooling tower staging control loop, and a boiler control loop. One of our Honeywell vendors gave me some example lead lag control loops for pumps. One of them has some logic loops, control loops, and math functions for a counter. I am assuming that this logic will rotate the pumps after a certain amount of time. The program he sent me was for a boiler system. So they created a control loop to enable the pumps below 60 degrees OAT. The output of this control loop is referenced in all of the logic loops for the pumps and counters. Being that my system was a cooling tower system. I was wanting pumps to run all of the time. If I deleted the pump control loop output from the logic. I am wondering if everything logic wise with the rotating lead lag would still work right?

I was also wondering if someone could explain how the whole integration time works on these control loops. What does increasing it do? What is this time based on? How can I know where to set this? Is there some type of formula that can be used to calculate this?

I have a copy of the program I was given if anyone wants to see it.

Thanks!

2. Let me look at the program and I'll try and answer it, you should practice programming the 15c, there's a simulator avaliable online that will attach to the Lonspec software. As for integral, it's the funtion in the PID loop that allows the loop to stabalize before making another change to the output. The velocity model of the PID loop is the most popular but there are more out there, you have to look at the math to completely understand what's happening. In the volocity model the integral should be set as high as possible without causing erratic operation of the output, trial and error at first. Experience through practice will help you most.

Let me look at the program and I'll try and answer it, you should practice programming the 15c, there's a simulator avaliable online that will attach to the Lonspec software. As for integral, it's the funtion in the PID loop that allows the loop to stabalize before making another change to the output. The velocity model of the PID loop is the most popular but there are more out there, you have to look at the math to completely understand what's happening. In the volocity model the integral should be set as high as possible without causing erratic operation of the output, trial and error at first. Experience through practice will help you most.
I have the simulator already and it does help a lot. On this particular program it is hard to fake out all of these counters and math formulas because I really don't know what there doing entirely. I know they are probably rotating the pumps every 100 hours, but I would like to understand how this program exactly works to help me fully understand this logic.

As far as the integral goes I have seen a lot of control loops on jobs without any integral. I am just trying to grasp the difference in all of the manufacturers integral setpoint. Some manufacturers use integral gain and it seems that this controller uses integral time. Will the simulator allow me to see the effect of this adjustment? Do you have a email I can send the program too?

4. I just put my email in my profile, I thought I had already put it there.

I just put my email in my profile, I thought I had already put it there.
I sent the program to your email. It came back saying the email doesn't exist. I just tried to send it again. Let me know if you get it.

Thanks!

6. You were right I forgot the "2". If only I could type decently I would be a hellofagood programmer. Most of mu problems end up being typos.

Let me look at the program and I'll try and answer it, you should practice programming the 15c, there's a simulator avaliable online that will attach to the Lonspec software. As for integral, it's the funtion in the PID loop that allows the loop to stabalize before making another change to the output. The velocity model of the PID loop is the most popular but there are more out there, you have to look at the math to completely understand what's happening. In the volocity model the integral should be set as high as possible without causing erratic operation of the output, trial and error at first. Experience through practice will help you most.
I finished this job today. I got all of the programming working, and everything seems to operate really smooth. One question I do have is what do you guys typically set the delay to before a pump failure is issued on a Loop Water System for a water source heat pump system? I set it at 15 seconds, but I am not sure if the heat pumps would trip or not with a 15 seconds loss of flow. Where do you guys normally set this. Thanks

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Am interested in learning how it works, would you share the program backup with me?
Reed Rutkowski

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