Power Factor and New Power Company Digi Meters

Whether or not they correct for power factor I don't know, but I suspect they are just a lot more sensitive to low currents. Our old mechanical one would not noticeably rotate even with things like VCR on standby and the bell transformer drawing current. I suspect the new one sees everything. Haven't attempted to calculate how much extra that would be.

Both old and new measure true power, though there are moves afoot to meter kVAr's as well because of the increasingly bad power factors of modern loads. Industrially they already meter kVAr's but the technology to do it domestically was too expensive, not any more. Greg

I ask all this because I'm in dispute with power company (BRITISH GAS) over this

suddenly having power bills of =A3300

when average before digi meter was under =A3170 ish

used the lathe yesterday for one hour ...it's on a rotary converter.

lathe is 2 hp converter is rated at 5.5 hp

20 units used in 24 hours according to the new meter. didn't do any cooking ...only TV and lights, computer and lathe used in the 24 hours.

All i ask people to do is ...check their digital meter when operating things with windings etc .

Just so that I've got something to back up me up when on the phone to them.

all the best...mark

My consumption certainly appeared to rise after the meter was changed.

Tim Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service

OK they have just been on the phone to me ...in the last few mins

It now seems that I've used 27 units since 12.30 yesterday ...'till 3 pm todays .

Guy on the phone agreeing that the domestic unit may not compensate for power factor .

Got to take regular readings now for the next 7 days .

Then they will delve deeper.

Urge everyone with these digi meters to look carefully at the power consumed when using equipment /tools etc with windings .

and report back here .

all the best.mark

"correct"...

swapped from

modern

I ask all this because I'm in dispute with power company (BRITISH GAS) over this

suddenly having power bills of £300

when average before digi meter was under £170 ish

used the lathe yesterday for one hour ...it's on a rotary converter.

lathe is 2 hp converter is rated at 5.5 hp

20 units used in 24 hours according to the new meter. didn't do any cooking ...only TV and lights, computer and lathe used in the 24 hours.

All i ask people to do is ...check their digital meter when operating things with windings etc .

Just so that I've got something to back up me up when on the phone to them.

all the best...mark

I have a secondary meter so that I could check if I wished. This is an old pre-payment meter that has had the coin box removed and trivial electronics added to generate an opto-isolated pulse every rev of the disk which triggers an interupt on my energy monitoring software. I display three bargraphs of power consumed : a/ per minute for the last 60 minutes. b/ per hour for the last 24 hours and c/ per day for the last 31 days. I also monitor water consumption on the same system and when I wrote the software made provision for gas consumption but haven't found an easy or safe method of metering the gas so its display just mimics the electricity ! Gets a bit alarming when I've been running my new 15KW converter for a bit - whacking great graphics bars sticking out of a low field !!!

AWEM

A typical one measures just kWh, the "technical" manual is available for download here.

Biggest problem I had was that they billed us based on estimates for two years. The estimates were substantially less than the meter readings would have been. I didn't notice it because the domestic management dealt with the bills... A £700 pound electric bill after they did finally read the meter was a bit of a shock.

Mark Rand RTFM

operating

...pah you think you have problems !!! ..... I've just paid Powergen £2,900 for gas as we've been on estimated readings at one of my shops for the past year.

AWEM

That one measures both active and reactive power separately, is that what they are installing now?, it would certainly fit with what I've heard about their plans to meter kVAr hours in the future.

But the fact remains they presently bill on active power only, and any meter either mechanical or electronic is supposed to read only active power so the kVAr hours display on that meter should be ignored.

Greg

Looking closer, that manual covers a range of meters including a kW hour only type for domestic and even an export power for use with grid connected generators, they're obviously thinking ahead to the micro CHP market.

Greg

I've just measured the units used over a two hour period.

The converter was switched on and I was machining plastic...making an interface for an LPG conversion ...for the pipe to pass thru the floor of my car .

Over a two hour period I used 11 units

This cant be right......that's over 5500 watts draw.

If I was using that much, it would be so hot in the workshop It would be like having 5 1/2, one bar electric fires switched on .

The workshop wasn't hot !

This just cant be right. :(

All the best...mark

And if the price of electric went up in that 2 years they almost certainly charged you at the new price for the 'old' juice. It's called back-billing and they have been told to stop it but still try it on. Inflated my bill by over £100 but I got it back, took over a year and 2 energywatch referrals but I won!

Sorry for butting in - newby lurking - but this thread got my attention!

Cheers Andy Parker, Agate House Lapidary Ulverston, Cumbria, England snipped-for-privacy@agatehouse.co.uk

Thankyou Mike

I take it that the model that measures reactive energy is the one that they should of installed.

Is reactive energy another word for power factor .

All the best.mark

No, they should have installed the one that measures active energy as that's all that is metered domestically.

No, reactive energy is the energy that flows in the reactive part of the load i.e. the inductive or capacitive elements of the load and is measured in kVAr hours (kilo Volt Amp reactive hours)

Power factor is the ratio of the true power to the apparent power i.e. watts/volt-amps or W/VA and is a measure of how close to a resistive load it is. A pf of 1 is purely resistive and any lower value contains inductance and/or capacitance (or switched mode see below). A load consisting of pure inductance and/or capacitance has a power factor of 0 as there is no true power dissipated in it, though in reality no such pure components exist.

Another way to visualise it is that Watts are due to the current that is in phase with the voltage and VArs are due to the current that lags (inductive) or leads (capacitive) the voltage by 90 degrees.

Low power factors are a problem for the national grid as the lagging (most common) current causes heating of the distribution network so loses energy, but is not billed domestically so they don't get paid for it, industrially it is billed or at least limited by contract.

Then to get you really confused there are the now very common switched mode power supplies in everything from PCs to video recorders, these draw current in peaks but in phase so aren't leading or lagging, yet they still result in a bad power factor and heating of the grid for reasons that are just too complicated to explain here.

Greg

Thats the exact one I have

but it says in the literature that there are a few different models

I want one that sorts out my lathe and converter so it does not get read as if its using 5500 watts per hour ... my old mechanical meter didn't work like that ...I want it back !!!

if every time I use my lathe for an hour its going to cost me dear .=2E.I'm not going to use them .;..because ...I will end up with bills of =A3300

in simple terms .. what one model is it .

The one I have now is model number 5235a and is the wrong one for my application

All this reactive stuff etc is over my head

What do I tell the guy on the phone ...

All the best..mark

I was with powergen for about two years when I moved into this house. In all that time they didn't manage to send me a single correct bill. Each time I rang someone up they would change it, but by the time it got out to me they would have got it wrong again. Most incompetent company I have ever dealt with. Even when I gave them meter readings they would send out bills with "estimated" figures. But as they had never read the meter there was no accurate data to base the estimate on. Final straw came when they sent me an "estimated" bill that said I'd used several hundred pounds worth of electricity in a week!! And then changed my direct debit to a ridiculous figure based on the estimated bill. I am now with a different power company.

Regards Kevin

If you still power the lathe from a 13 amp socket then take a trip to Maplins and get a plug style power meter.

It will read voltage, current drawn, power factor and watts used including peek load.

Very useful little tool for checking computers etc.

Takes up to 3Kw I think and costs generally less the £24

Adrian

You occasionally see these in Lidl (or Aldi ?) for under a tenner the display is rather hard to read but they seem to work OK.

-another adrian