# Drop in frequency over several months in large building



## Mitchman (Nov 17, 2018)

//tinyurl.com/y9yx9k3h


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## macmikeman (Jan 23, 2007)

Mitch you are an IT guy and this forum is for electrical professionals. It was part of the signup . I would blame your problem on your elected officials since it's the Bay Area....


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## joebanana (Dec 21, 2010)

Thanks for filling out your profile. I think mac covered the do's and dont's of the in's and out's, whereas the what if's, and the, I wouldn't if I were you, is covered in the handout.
Now, if you're talking about line frequency, what are you measuring it with? Anything more than .5 Hz. deviation is uncommon for utility power. If you have more than that you could complain to PG&E, as if it would do any good.


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## 460 Delta (May 9, 2018)

60 cycle power is usually rock steady, with less than half a cycle up or down variation like joeb says. With the utilities all interconnected, it is going to cause problems for everyone if one generation plant starts slacking in frequency. I believe the problem lies elsewhere, or you have a meter that's giving you bad info.


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## Southeast Power (Jan 18, 2009)

Mitchman said:


> Hello
> 
> I thought I would as some experts here in the commercial space to see if they have ever encountered an issue like this. I am usually stuck behind a computer making sure all my servers are happy but I actively monitor my Uninterruptable Power Supply's for my server rooms as well.
> 
> ...


Harmonics and mysterious sine waves used to be a common topic when the entire industry was transiting into the electronic age.
It's not unheard of but pretty much a rare topic in the world of an everyday electrician.
Look up 3rd and 5th harmonics and you will see where I'm going with this.


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## MikeFL (Apr 16, 2016)

@*JRaef* would know what PGE is putting out in that area. He's right there and he's the godfather of frequency.


I would first suspect your reporting equipment is lying to you. Get someone qualified with the right equipment to analyze your frequency.


What kind of numbers are you seeing?


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## John Valdes (May 17, 2007)

Welcome to Electrician Talk Mitchman.
Thanks for taking the time to fill out your profile.


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## Mitchman (Nov 17, 2018)

Thanks, everyone for your advice on the next steps. It crossed my mind that my UPS may be lying to me, which would be a first for power inputs. I think a more likely scenario is harmonics are making the UPS think there is less frequency then there is. Will see if I can get a hold of an oscilloscope and check it out.


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## Mitchman (Nov 17, 2018)

MikeFL said:


> @* would know what PGE is putting out in that area. He's right there and he's the godfather of frequency.
> 
> 
> I would first suspect your reporting equipment is lying to you. Get someone qualified with the right equipment to analyze your frequency.
> ...


*

It has dropped from 50 Hz(which is odd)to 44.8 Hz in the last 14 months according to my device. I think the next steps are to doublecheck to make sure my device is not lying to me. Thanks for your help*


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## MikeFL (Apr 16, 2016)

If POCO were delivering 44Hz there would be big time screaming by industry. It's not happening. Your equipment is failing (wearing).


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## Mitchman (Nov 17, 2018)

MikeFL said:


> If POCO were delivering 44Hz there would be big time screaming by industry. It's not happening. Your equipment is failing (wearing).


Just wondering if it could be the transformer on the floor, I assume large buildings have some type of transformers on each floor. So maybe its past the POCO and a floor issue. I found this article from APC and frankly it concerns me because we do have a large amount of PC deployed.

Harmonics overload building power transformers and cause them to
wear out.
Power transformers are rated in KVA and are designed to carry currents at the power line
frequency (50 or 60 Hz). The factor that limits the power handling capacity of a transformer is
how hot it gets. The heat in a transformer is caused by the inherent resistance of the
transformer and the current carried by it. When a power transformer carries harmonic
currents, an effect known as the proximity effect (sometimes confused with the eddy current
effect) causes the effective resistance of the transformer to increase with frequency. The
result is that the transformer rating must be decreased if the transformer carries significant
harmonic currents, otherwise it will overheat and wear out due to insulation degradation.
Transformer failures are often catastrophic and emit noxious fumes or fire; they can result in
facility closure for days and a variety of health and safety consequences.
For this to be a problem, three things must happen together: 1) The transformer must be
loaded nearly to capacity (unusual); 2) The transformer must have a poor "K" factor rating
(bad proximity effect design); and 3) The load in the building must be mainly PCs. This is a
real potential problem especially in situations where a large number of PCs have been
deployed. Again, the location for concern is typically an office environment with high PC
density such as a call center. The problem is no longer of concern in the data center
environment as explained previously.
Abatement and mitigation of harmonic problems
There are a number of approaches to avoiding harmonic problems. These include:
1. Specifying equipment that does not create harmonics
2. Correcting harmonics
3. Oversizing neutral wiring
4. K-rated transformers


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## Mitchman (Nov 17, 2018)

Anyway, will pause and test. Thanks Mike!


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## Signal1 (Feb 10, 2016)

macmikeman said:


> Mitch you are an IT guy and this forum is for electrical professionals. It was part of the signup . I would blame your problem on your elected officials since it's the Bay Area....


It has to be Facebook. That little Z guy always taking my frequency.


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## Wirenuting (Sep 12, 2010)

Signal1 said:


> It has to be Facebook. That little Z guy always taking my frequency.


There was a FB outage the other day... 30 minutes of normality and it was so nice,, the sun came out, I saw a birdy fly past..

And they fixed the hurts problem right.


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## MikeFL (Apr 16, 2016)

Go to Grainger and get a Fluke meter off the shelf and see what that tells you the frequency is. 



$120 for a Fluke 117.


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## Southeast Power (Jan 18, 2009)

The frequency isn't changing if your voltage is staying the same.
No mater what, some kind of generator is making your power.
Put your diesel on line and see if your UPS likes it any better.


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## glen1971 (Oct 10, 2012)

Mitchman said:


> It has dropped from 50 Hz(which is odd)to 44.8 Hz in the last 14 months according to my device. I think the next steps are to doublecheck to make sure my device is not lying to me. Thanks for your help


It dropped from 50Hz? Do you have a separate generator, that supplies the 50Hz power? With the North American norm being 60 Hz, any 50 Hz systems I've worked on had a separate generator or frequency converter to supply it..

What voltage are you seeing? What is the frequency you are measuring? What kind of UPS are you working on?


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## splatz (May 23, 2015)

TBH I don't know how harmonics would appear to the UPS as a different frequency, but it definitely sounds plausible. Especially with APC UPS's - not a fan. 

It certainly can't hurt to see that your transformer is K-rated and suitable for the load, and if there's any undersized neutral present. If the harmonics are coming from the UPS load, I think you'd have to deal with the UPS neutral wiring. But it seems like this problem is like bigfoot: it's talked about more than it's actually seen. 

They always say IT equipment all runs on switched mode power supplies which are heavy on harmonics, but there may be fewer of those power supplies around these days, maybe just in the workstations. Are the workstations on the UPS's or just the data center equipment? Is there anything besides IT equipment on the UPS? 

I think if the UPS is online / dual conversion type, the isolation of the load side from the line side would keep any harmonics on the UPS load from showing up on the line side. 

It could also be on coming from fluorescent lights, maybe LED conversion ballasts, VFD drives on the HVAC system, lots of other things. 



Mitchman said:


> Just wondering if it could be the transformer on the floor, I assume large buildings have some type of transformers on each floor. So maybe its past the POCO and a floor issue. I found this article from APC and frankly it concerns me because we do have a large amount of PC deployed.
> ...
> There are a number of approaches to avoiding harmonic problems. These include:
> 1. Specifying equipment that does not create harmonics
> ...


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## Mitchman (Nov 17, 2018)

Well, hooked up a fluke meter to the socket the UPS is plugged into and it reads 60Hz. Which gives me some relief that it's not a floor-wide issue and a danger to take out all the computers(400+) on the floor.
So definitely something is up with the UPS. There is an HVAC unit next to the UPS which runs constantly, its on the same panel but not the same breaker. Going to send logs to APC (the UPS manufacturer) to see if they can determine next. Thanks again for everyone's input!


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## MikeFL (Apr 16, 2016)

Thanks for the update. Too often someone comes on here and obtains what would otherwise be $2500 worth of consulting and they never come back and tell us what it was. Glad it worked out for you. $120 solution and now you have a new toy!


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## just the cowboy (Sep 4, 2013)

What Mike FL said x10. Not enough people get back to us.


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## glen1971 (Oct 10, 2012)

Mitchman said:


> Well, hooked up a fluke meter to the socket the UPS is plugged into and it reads 60Hz. Which gives me some relief that it's not a floor-wide issue and a danger to take out all the computers(400+) on the floor.
> So definitely something is up with the UPS. There is an HVAC unit next to the UPS which runs constantly, its on the same panel but not the same breaker. Going to send logs to APC (the UPS manufacturer) to see if they can determine next. Thanks again for everyone's input!


What does your new meter tell you about the UPS output? Voltage and frequency?


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## Southeast Power (Jan 18, 2009)

I'm not complaining but, the next guy with a freq problem has to be asked if he has some new fancy AC unit with DC motors on the same panel.


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## Mitchman (Nov 17, 2018)

Southeast Power said:


> I'm not complaining but, the next guy with a freq problem has to be asked if he has some new fancy AC unit with DC motors on the same panel.


LOL, Fluke read right on the money 208 V, 60Hz. Pretty clean wave.

Updated the firmware on the UPS and it fixed the issue. Reading 60Hz

I did have a certified "paid" electrician come out and help me test. Again thanks for all the advice and I am planning to take my electricians test when it finally rolls around in 2020 in SF. 

Cheers!


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## splatz (May 23, 2015)

Mitchman said:


> LOL, Fluke read right on the money 208 V, 60Hz. Pretty clean wave.


Which model Fluke did you buy?


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