Smart meters and poor power factor?

[eccerr0r]

Anyone got their residential power meters "upgraded" to a "smart" meter? I wonder how much your electric bills changed.

It looks like my neighborhood is getting these smart meters installed which to me seems like a lose-lose to the consumer. The two things that I fear that would -increase- my bills:
1. My power factor is nowhere near unity. With a smartmeter they can tell and charge me more.
2. And of course they can measure power during peak versus off-peak. Likely people will all be needing power during peak times.

Ideally it would be best if it were possible to store excess power during off peak hours as well correct power factor to near unity, but these aren't happening.

While I do have many computers, there already exists many things with crappy power factors:
- central AC compressor and blower
- washer and dryer (I suspect the dryer is closer to unity because it's electric)
- dishwasher
- CFL and fluorescent bulb ballasts

I use gas heating so they don't appreciably affect power consumption. Why I don't have a gas stove and gas dryer I don't know...

I don't know about the power factor of microwave ovens but suspect these are not unity either...

The only things I have that are closer to unity:
Stove, toaster, toaster oven, incandescent lamps, and of course PSUs with Active PFC. I think I only have two (the ocz stealthxstream2 and the antec neohe). Most other PSUs have no PFC, maybe a handful with passive PFC.

Overall I figure I have really crappy power factor, but maybe they(the power company) will overlook it and only bill real watts used... But with a smart meter, all bets are off. Anyone get dinged for power factor? (Please also indicate locale, would be interesting where they are measuring PF in residential areas.)

[ratdude747]

Re: Smart meters and poor power factor?

I had this in my AC electronics class this semester. I have a test over this (plus polyphase systems) on wednesday.

Here's how it works:

we have 3 AC powers:

P (watts)- real power only (resistors)
Q (VAR)- reactive power only (inductors and capacitors)
S (VA)- apparent power, P and Q combined, P + Q = S (if added as vectors/phasors), P^2 + Q^2 = S^2 (magnitude only)

PF is the power factor, PF = P / S

The supply current is found using S. However, the only power used up in the end is P, as the Q portion is returned to the grid whenever the load is reduced. Hence why your power is billed by the P portion, not the S portion (and why the meter says kWH, not kVAH).

However, PF becomes important in terms of cost in a different way, particularly for large factories. The lower the PF, the higher the ratio of wire size to expected power draw is (aka they get less $$$ off billed power but they have to use heavier supply wires). As a result, if a factory's PF is lover than ~0.9, there usually is a fee. My professor said that for instance, Most of a certain Pepsi factory's power bill was PF fees, not P used (forgot which one and the numbers though).

However, for home owners, there usually is no fee because the wire gauge used for a house isn't as affected by PF due to the smaller scale and the average PF of a house being somewhat high, since the ratios of inductive load to resistive load is less (less/smaller motors, more lights and heating elements).

Therefore, I doubt smart meters will change the billing scheme in terms of PF and P vs S.

[eccerr0r]

Re: Smart meters and poor power factor?

Well, it's not only the wiring in one particular house. If you consider the whole neighborhood as one big company...then there's a problem. The "uplink" has to suffer the poor power factor.

Before when it was not cost effective to monitor 1000 homes versus one factory, it made sense just to use the real power with a regular meter. Now with electronic meters that can do this kind of stuff... they can use this data to discourage bad power use...

[Kiriakos GR]

Re: Smart meters and poor power factor?

they can use this data to discourage bad power use...

I consider this as positive turn out if this speculation it does have a base.
Especially now days that we must adjust our style of living by looking forward at using solar energy.

[ratdude747]

Re: Smart meters and poor power factor?

I consider this as positive turn out if this speculation it does have a base.
Especially now days that we must adjust our style of living by looking forward at using solar energy.

That doesn't make a difference. In order make power grids (and many pieces of equipment, both consumer and industrial) work efficiently, you have to use AC transmission, which means power factor comes into play.

Furthermore, the issue power factor causes has more to do with peak current draws (wire sizing) and less to do with power output/usage.

I'm nto saying solar is bad or not worth research but it sure isn't going to eliminate power factors.

[999999999]

Re: Smart meters and poor power factor?

While I have read of some who had smart meters installed and saw their bill go up, when ours was installed the bill stayed essentially the same as the prior year, but a little higher due to a hot summer where the A/C ran more often.

When I read of someone overbilled it tends to be that the meter wasn't properly calibrated so the reading was way off.

[eccerr0r]

Re: Smart meters and poor power factor?

That's somewhat alarming, how do they calibrate?

And the other thing - how do smart meters measure wattage? Does it integrate (in the calculus aspect) current times voltage at a high sampling rate or does it average it using low sample rate? Or does it use some other mechanism?

The old mechanical system is actually correct for the most part, I wonder if sampling error, if it indeed does, will introduce inaccuracies? Wouldn't it be "nice" if they sampled the current at the peak of each wave? That way if we had terrible power factor we'd be paying up the wazoo for power we didn't use (due to power factor)?

[999999999]

Re: Smart meters and poor power factor?

^ calibration is at the factory, it's defective if it wasn't calibrated right there. This is how it goes, increase the complexity of a system and the errors go up too.

[eccerr0r]

Re: Smart meters and poor power factor?

That's pretty scary, how far off can calibration get? And is it common?

As these should be measurement equipment there should be some intrinsic accuracy?

I'm dreading the 'upgrade' ...

[999999999]

Re: Smart meters and poor power factor?

I've no idea, this is the kind of info they DON'T WANT YOU TO KNOW.

I wouldn't worry too much about it though, keep records of your power bills for comparative purposes.

[japlytic]

Re: Smart meters and poor power factor?

I think the meters in our new house are multi-rate, even though they are not read remotely.

Also, I read about plug-in energy saving gimmicks (the ones which have a large power factor correction capacitor) won't save you energy by improving power factor, and they can be outright dangerous, considering the fact that the capacitor would store charge for some time (and deliver it to the pins) after being unplugged.

With smart meter legislation, it should (along with other new legislation) always be complimented with education.

[ratdude747]

Re: Smart meters and poor power factor?

I think the meters in our new house are multi-rate, even though they are not read remotely.

Also, I read about plug-in energy saving gimmicks (the ones which have a large power factor correction capacitor) won't save you energy by improving power factor, and they can be outright dangerous, considering the fact that the capacitor would store charge for some time (and deliver it to the pins) after being unplugged.

With smart meter legislation, it should (along with other new legislation) always be complimented with education.

yeah, PCF correction does nothing for consumers (since they are only billed by the real power, not the apparent power)... what they use at large factories is much more safe than some plug in bullcrapper.

Even if consumers were billed by apparent power, to work, the plug-in would have to have a way to adjust its value based on the reactive load at any given moment.

[eccerr0r]

Re: Smart meters and poor power factor?

Yes. that is a problem too - passive correction does nothing for residential not because they are billed by real power (because smartmeters can tell the difference between real and apparent power) but because the duty cycle of devices are so random that you can't correct PF in a way that it makes a difference. The only way is to correct it at each device, so when it's on, it has unity PF...

Once again it is to help out distribution, local wiring tends to be well suited for any load. But if they use these smart meters to "encourage" larger PF's by increasing the price of power for poor PF's...