Negative Pf residential Home

[Besoeker3]

Surely it is leading or lagging PF, not negative/positive??

 

[jim dungar]

I would have thought the same thing. I even told him that as long as the doors are closed, the food should stay fresh, but he says that even with the doors closed the temperature gets warm enough within a short time span.

This guy is a little wild. He has ammeters clamped on all over the place. around the mains, around the branch breakers, around the ground rod... if current can flow on it, hes clamped a meter around it. hahaha.


I get my hands in it when I can. I think the guy is up to 7 or 8 different electricians at his house poking around. I had phoned a good retired electrician recently to come help as well. Even he was stumped.

I'll shoot a private message to Fred... thanks for the tip. The data just doesn't make sense. I haven't seen a situation like this before.

If the fridge cannot maintain a relatively constant temperature for a few hours with the doors closed, there is something wrong with it. Heck, even my camping cooler can keep things safe for two hours.

Does he measure the current in the neutral and the hot for each breaker, at the same time? Is he taking voltage measurements concurrent to his current measurements? Has anyone run a temporary extension cord direct from the breaker to the fridge, bypassing all internal house wiring?

It sounds like he gets more attention from electricians rather than his appliance repair people (do they still exist?).

 

[Rock86]

It sounds like he gets more attention from electricians rather than his appliance repair people (do they still exist?).

I think they are busy fighting for Right To Repair. Things today are throw away... its a shame. But he did have the refrigerator replaced once, then a repair guy came and replaced parts they thought could be wrong... no change.

And i 100% agree... it should be keeping cool..

 

[winnie]

I think you might need to get one of these:

https://www.amazon.com/Mattel-Ghostbusters-Exclusive-Replica-PKE/dp/B004GWIYXI/

Honestly: computer support folk would sometimes identify problems located between the chair and the keyboard.

However if the problems are real, I'd be looking for something _outside_ of the electrical system that is causing both the original symptoms and causing problems with the measurements of the electrical system. Something like a nearby high power AM transmitter, or some other unexpected by real energy source impacting everything.

I can't re-read the entire thread. But what are the _ACTUAL SYMPTOMS_ at the home. Not the strange measurements, but the actual problems that triggered the measurements to be made in the first place? As I recall:

flickering lights
a fridge that would stop working to the point that food would go bad, and then start working again without tripping a breaker
anything else?

Jon

 

[tortuga]

Here is the summary as I understand it:

• Flickering lights + fridge issue. Newly purchased house newly built.
• With the main breaker off electrician measured 5-10A current on the neutral.
• Clamping by electrician on the EGC also showed objectionable current.
• Utility pulled meters from the neighbors and discovered that neutral current increased at the house.
• Utility installed their own data logger and did not share results.
• Utility dragged their feet for months and just recently replaced the transformer.
• Homeowner tried different LED bulbs.

Correct me if I missed anything.

I suspect Utilities never do stuff they dont have to so probably was a issue on their end.

Things we dont know :

• Did they recheck the current on the neutral now that transformer has been replaced?
• Does the utility use TWACS metering?
• Do the lights still flicker after transformer has been replaced?
• Do the lights still flicker with incandescent bulbs?

 

[karlbuzz]

Shaved,bare spot on service entrance cable back feeding mast/conduit.

 

[jaggedben]

Surely it is leading or lagging PF, not negative/positive??

Negative power factor is one way to describe backfeeding or reverse power. No reason to believe that's going on here though.

If the measurement devices (CTs) are installed or connected backwards, then you get a negative power factor measurement by convention, but not in reality. I.e user error.

 

[tthh]

When you get to this stage, you just have to go with divide and conqueror. In this case, that will be disruptive to the house inhabitants, but that's what has to be done to get to the bottom of this. Take one of the issues and ignore the others and divide this down and down until you have a simple set of stuff still connected, but exhibiting the problem. So, for example, the flicking LED light. This might be an ok time of year for this as well as heating and cooling might be ok to not operate for extended periods. I might start by shutting off all the breakers in the house except that of the flicking LED lights. Then figure that out. You just have to get it to the smallest problem possible and figure that out. Once one problem is figure out, add one more small piece and see if it is all still fine...then add more and more and more.

 

[Besoeker3]

Negative power factor is one way to describe backfeeding or reverse power. No reason to believe that's going on here though.

If the measurement devices (CTs) are installed or connected backwards, then you get a negative power factor measurement by convention, but not in reality. I.e user error.

Leading or lagging. Not negative.

 

[jaggedben]

Leading or lagging. Not negative.

If reverse power is conventionally negative, and power factor is real power over apparent power, then power factor will be negative when power is flowing in reverse.

Convincing a seasoned EE

I'm trying to convince an EE hired by the property owner that there will be very little to no current flow on the Neutral so as not to have to take an 0.8 derate in a 277/480 combiner panel wiring (no loads, just my 3 SMA Core 1 inverters). He's telling me 277V loads inside the building will...

forums.mikeholt.com

 

[jaggedben]

Or rather, it's all a matter of convention.

What is the difference between IEEE and IEC standards in terms of kW, kVAR, and PF (power factor)? | Schneider Electric Global

 

[Besoeker3]

If reverse power is conventionally negative, and power factor is real power over apparent power, then power factor will be negative when power is flowing in reverse.

Convincing a seasoned EE

I'm trying to convince an EE hired by the property owner that there will be very little to no current flow on the Neutral so as not to have to take an 0.8 derate in a 277/480 combiner panel wiring (no loads, just my 3 SMA Core 1 inverters). He's telling me 277V loads inside the building will...

forums.mikeholt.com

But it is not negative. AC are just that - alternating, neither positive nor negative.

 

[jaggedben]

See previous post.
Of course it's AC.

 

[Rock86]

Here is the summary as I understand it:

• Flickering lights + fridge issue. Newly purchased house newly built.
• With the main breaker off electrician measured 5-10A current on the neutral.
• Clamping by electrician on the EGC also showed objectionable current.
• Utility pulled meters from the neighbors and discovered that neutral current increased at the house.
• Utility installed their own data logger and did not share results.
• Utility dragged their feet for months and just recently replaced the transformer.
• Homeowner tried different LED bulbs.

Correct me if I missed anything.

I suspect Utilities never do stuff they dont have to so probably was a issue on their end.

Things we dont know :

• Did they recheck the current on the neutral now that transformer has been replaced?
• Does the utility use TWACS metering?
• Do the lights still flicker after transformer has been replaced?
• Do the lights still flicker with incandescent bulbs?

• Did they recheck the current on the neutral now that transformer has been replaced? - YES
• Does the utility use TWACS metering? - NO
• Do the lights still flicker after transformer has been replaced? - YES
• Do the lights still flicker with incandescent bulbs? - DID NOT TEST THIS THOUGHT.

 

[busman]

But it is not negative. AC are just that - alternating, neither positive nor negative.

Agree, it is just the relationship of the voltage to the current waveforms. I guess if you somehow stipulated that positive current flow is toward the customer, then you could have "stipulated" yourself into a negative power factor, but personally don't believe the definition supports that. Definition follows: the ratio of the actual electrical power dissipated by an AC circuit to the product of the r.m.s. values of current and voltage. The difference between the two is caused by reactance in the circuit and represents power that does no useful work." In other words, PF only seems to be defined for dissipation, not generation.

Mark

 

[jaggedben]

Agree, it is just the relationship of the voltage to the current waveforms. I guess if you somehow stipulated that positive current flow is toward the customer, then you could have "stipulated" yourself into a negative power factor, but personally don't believe the definition supports that. Definition follows: the ratio of the actual electrical power dissipated by an AC circuit to the product of the r.m.s. values of current and voltage. The difference between the two is caused by reactance in the circuit and represents power that does no useful work." In other words, PF only seems to be defined for dissipation, not generation.

Mark

So if you set up a device to measure dissipation in a circuit but it ends up measuring generation then how do you choose to signify that?

 

[Carultch]

Surely it is leading or lagging PF, not negative/positive??

It's common that people assign a false sign to power factor, even though a net real power consumption of any kind is technically positive (assuming that's your sign convention). The phase angle can be positive or negative, and people commonly pass through the sign of the phase angle as the de-facto sign of power factor, even though both are technically a positive power factor.

Truly negative power factor would mean the average value of the product of I(t) and V(t) is negative over a full cycle, which would only happen if real power were flowing in the opposite direction you were expecting.

 

[Besoeker3]

It's common that people assign a false sign to power factor, even though a net real power consumption of any kind is technically positive (assuming that's your sign convention). The phase angle can be positive or negative, and people commonly pass through the sign of the phase angle as the de-facto sign of power factor, even though both are technically a positive power factor.

Truly negative power factor would mean the average value of the product of I(t) and V(t) is negative over a full cycle, which would only happen if real power were flowing in the opposite direction you were expecting.

I know what the score is. I was just trying to do it gently.

 

[busman]

So if you set up a device to measure dissipation in a circuit but it ends up measuring generation then how do you choose to signify that?

No matter the measurement device, generation is not dissipation.

Mark

 

[Rock86]

If I renamed the thread, would that make it less confusing?