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Thread: Power Quality Issue in Boilers

  1. #1
    Join Date
    Jun 2022
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    Hmm Power Quality Issue in Boilers

    Good afternoon,

    Recently we performed what was possibly the largest installation our company has ever done. A local waterpark added a new attraction, (The USA's very first Slide-Wheel. Intertwining slide tubing on the inside of a ferris-wheel like structure, that also rotates around like a ferris wheel. It's freaking neat.) and our company was responsible for heating/cooling the new addition as well as heating all of the pool water inside the new addition.

    We installed 2 MASSIVE Innovent Exhange Air units, as well as 3 separate, 1,000,000BTU boilers for heating the pool water. Ever since the job ended, we've consistently had problems with our boilers locking out due to error codes. This is where it gets interesting: Even though our boilers are not programmed to run together as if it were one unit, the lockouts always occur at the exact. same. time. And, they always lockout within a specific timeframe. (Around 5AM and then again sometime between 9 & 11AM) Our boilers are wired at 480V and are daisy-chained at the thermostat in the controls so that they work in unison, but they can also run individually if need be. I've spoken with the control guy who programmed the boilers and he has never encountered an issue like this before. It's been a real head scratcher for the past few weeks.

    I was finally able to get a technician from the distributor we bought the boilers from to come out and run some diagnostics tests on the boilers. He actually got to witness the boilers lock out right in front of him, which was good, otherwise I don't think he would've been able to find anything wrong.

    After running all of his tests, he told me that the issue had nothing to do with our installation or programming the controls incorrectly, but rather a power quality issue in the entire electrical system itself. He explained that the sensors in our boilers read pulsating frequencies in Hz instead of reading in Voltage. (I don't typically deal with Hz at all so this is all new to me) He also told me lockouts like these can occur when a large piece of equipment or machinery connected through the same electrical system is turned on. He suggested bringing a power testing company in to analyze the entire system for a few days to figure out what exactly is going on and then how to address and fix the issue.

    The reason I bring this issue here, is because the technician said fixing a power quality issue can be extremely costly, somewhere between $250,000 & $400,000. If I've learned anything during my time spent in this trade, it's that there are a multitude of solutions for any given problem. I'm confident that there has to be a better solution that wouldn't cost nearly as much. Since speaking with the technician, I've done some reading up on electrical engineering and harmonics. Some of what I have read faintly makes sense, but because I haven't had to work with Trigonometry or Calculus (Specifically dealing with sine and sine waves) since high school, the majority of what I've read is honestly too complex for me to fully grasp and comprehend. I did learn though that Hz becomes additive in a 3 phase system, and I do believe our boilers are 3 phase.

    I've theorized that the lockouts occurring between 9 & 11AM are being caused by the waterpark turning on their Slide Wheel for the day. That load of power is carried through the system and goes through our boilers, exceeding that 0-360Hz scale, causing the lockout as a safety protocol. (The error is listed as a fan burner error on the display)

    What do you guys think of all this? I understand the technician who came and diagnosed the issue was doing his job, and I respect and thank him for being able to find the problem when none of us could. I am not even sure who would have to foot the bill for a power quality issue because he made it sound like it wasn't the electrician's issue and wasn't clear on who exactly is responsible for an issue like this. So I wish I would've asked more questions while I had him there.

    Any insight would be greatly appreciated!

  2. #2
    Join Date
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    Share the info you have with the power company. This assumes they are your source of power.
    No man can be both ignorant and free.
    Thomas Jefferson

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  4. #3
    Join Date
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    Mixing oil and fire with a big spoon.
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    If the problem truly is within the park, then the power company probably won’t do anything. They stop at the POCC (Point of Common Coupling). But they can certainly install some power quality equipment to determine if it is coming from inside the park or outside the park. If it is from outside the park, they are responsible for tracking it down and getting the offending company to fix it. If it is from inside the park, you hope it doesn’t LEAVE the park because now you have to fix your stuff!

    Harmonics are typically going to be from non-sinusoidal power supplies (VFDs typically). You may need to track down the offending equipment with Power Quality Analysis meters (typically an electrical company would do this but most do not know much about harmonics and specialized grounding requirements of drives) and see why it is so bad. If the problem child is within specifications, then ask the company that makes the drive or whatever is causing the problem to offer a solution. This will usually be in the form of an electrical Filter or they may recommend an isolation transformer. It can be as complicated as adding or subtracting the length of the power feed as well. It all depends on what the real problem is and why.

    Good luck and let us know how it turns out.

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  6. #4
    Join Date
    Jun 2022
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    Wisconsin, USA
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    Thread Starter
    Quote Originally Posted by jayguy View Post
    Harmonics are typically going to be from non-sinusoidal power supplies (VFDs typically). You may need to track down the offending equipment with Power Quality Analysis meters (typically an electrical company would do this but most do not know much about harmonics and specialized grounding requirements of drives) and see why it is so bad. If the problem child is within specifications, then ask the company that makes the drive or whatever is causing the problem to offer a solution. This will usually be in the form of an electrical Filter or they may recommend an isolation transformer. It can be as complicated as adding or subtracting the length of the power feed as well. It all depends on what the real problem is and why.
    Both of our Innovent Exchange Air Units have 4 Separate VFD's on them. And now that you mention that, I recall the technician saying that one of our units is producing an excessive amount of Hz. If the issue does indeed come from inside the park, that may be the best place for us or the power quality company to start looking. Thank you for this, I'll be sure to update this thread once the problem is resolved!

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