Help with high THD in my area

Power Components
22

Current report (no pun intended :slight_smile: ) from Knoxville, TN according to my P10:

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23

Islip Terrace, NY
THD in 3.8
THD out .2
P20

24

Weare, NH
THD in:2.8
THD out:0.2

25

It looks like only 2 members have higher THD then I.
Any more?

Thanks

26

A somewhat related observation:
I lost power today. The little bit, 6 or so inches, of snow in NH took down some power lines. My whole house generator kicked in as expected. Being on top of my system hooking up my new DSDMK2 I heard a rhythmic clicking coming from my P15. Turns out my 22kW Generator is not as well regulated as Generac claims. The generator output was swinging from ~115 - 123VAC with ~ 4% THD. That input drove the P15 nuts. The P15 output was swinging wildly too. I freaked! Shut down, unplugged everything! Scratched the old squash for a few minutes before a bulb went off! Unregulated AC! When the Utility power came back problem solved.

I was thinking Iā€™d have to put off burning in my new DAC.

2 Likes
27

Weird, I couldnā€™t sworn the subject line said high with THC.

2 Likes
28

Your Colorado is showing. Haha

29

DFW TX

2.0 %. Incoming 0.1 % after the P-20 magic.

30

Across last year (Knoxville, TN):

THD-In: 3.5%-7.5%
THD-Out: 0.1%-0.4%

P20

31

Located in Lexington, KY.

P12

THD IN: 4.1-5.3
THD OUT: .1

32

Arlington VA
THD in. 2.1
THD out. 0.2
P15
Underground lines, substation about .5 miles away

33

Westminster, CO
7.4 in
.2 out
P15
varies a bit but generally around there.

34

South Boulder, CO
7.2% in
0.2% out
P5
Underground lines

35

Are they? Yes the IEEE 519 standard may specify 5% but does your utility agree to follow that specification? The IEEE does not enforce standards compliance. Itā€™s up to the government to do that if desired.

Keep in mind the 519 standard is a bit obsolete. This stems from the days when large computer disk drives were driven by synchronous AC motors. Here power quality was more critical. Since the 1980s disk drives are DC motor based and not at all sensitive to line power quality.

Most large enterprise class UPS systems run at around 10% THD which is considered quite acceptable for modern electronics. Switch mode power supplies simply donā€™t care.

And all that aside, you have a PS Power Plant that lowers the line distortion easily to below 1%. So whatā€™s your concern?

1 Like
36

Yes Power companies do have rules to follow as far as minimum requirements. Thatā€™s why I stated it at the beginning and 5% THD is one of them. I have equipment that require <5% distortion and the P20 is not big enough. Plus why would I be required to fix a problem with the power that is outside specifications.
Even my whole house generator has <5% THD
If you have a UPS that is higher than 5%THD I would suggest you not use it.

1 Like
37

Is there a legal document stating that? If so, I guess you can sue them? What equipment do you have that requires <5% AC line THD?

I am responsible for two Liebert UPS systems. One 750KVA and a second 350KVA. Spec is 10% THD on output. Liebert is the Rolls Royce of UPS systems.

38

Yes however they contaminate everything else that is plugged in.

39

Yes they do, but thatā€™s life today. In some countries you canā€™t even legally sell linear wall wort power supplies anymore.

40

Not necessary as they are working to fix the issue. I didnā€™t ask for legal advise or comments about what I was seeking.

41

OK then, it sounds like they are on it. Let us know what they ultimately get the distortion down to.

1 Like