Smart Meters and power factor correction - Page 1
Forum section: electronics / general

author: tttonyyy
author_rank: Regular Contributor
timestamp: August 10, 2022, 10:31:38 am
content: Someone here might know this - do Smart Meters correct for power factor?For example, I have a microwave that (at standby) draws 163mA @ 240V which sounds like 39W (ouch - expensive way to run a front panel clock). But the power factor is 0.02.Will my snazzy EDMI ES-10B smart meter be billing me for 39W or 1W?

author: jonpaul
author_rank: Super Contributor
timestamp: August 10, 2022, 10:38:14 am
content: Utility billed energy is measured in kWh, the meters are quite précis.The stand-by power of all connected devices will add up, and PF be ~ 0.5..07.By national regulations electronic devices over a certain wattage must be PFC.Check applicable regulations in your area, eg IEC in EU.bon chancej

author: tttonyyy
author_rank: Regular Contributor
timestamp: August 10, 2022, 10:45:56 am
content: According to the datasheet here:https://www.edmi-meters.com/wordpress/wp-content/uploads/2018/05/ES-10B-Factsheet-English.pdfQuoteIt sounds as though "old" induction-disc meters that only measure real power (that in phase with voltage) would not charge for reactive loading, but that may not be true of Smart Meters.

author: jonpaul
author_rank: Super Contributor
timestamp: August 10, 2022, 12:17:06 pm
content: check out the smart meter spec sheet and metering regulations applicable in your areaAll meters that affect the rates and electrical bill of utilities are tightly regulatedhttps://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/381535/SMIP_E2E_SMETS2.pdfLarge industrial distribution ovrr 50...250 kva, have utiliy surcharge for excessive VARs, hence PFC capacitor banksj

author: wraper
author_rank: Unknown
timestamp: August 10, 2022, 12:20:49 pm
content: Residential meters don't.

author: tom66
author_rank: Super Contributor
timestamp: August 10, 2022, 12:27:42 pm
content: Quote from: wraper on August 10, 2022, 12:20:49 pmThey do or otherwise they'd bill you for kVAh. UK domestic customers are only billed for kWh but to accurately measure kWh you need to know the power factor (or at least measure enough to calculate it)My meter even shows you kVAh and kWh separately if you dig through the menus (UK SMETS2 domestic energy meter), though I'm only billed for kWh and you can get the in-home display to show kVAh. It doesn't show the calculated power factor but I know the accuracy must be within +/-3% across the full dynamic range - I wouldn't be surprised if this is over e.g. 0.1PF to 1.0PF - and in the negative for solar/battery systems. I would imagine to achieve this accuracy and linearity it must be sampling the current waveform at a reasonably high sample rate with a modest ADC - probably at least 10ksps at 16-bit or above.

author: wraper
author_rank: Unknown
timestamp: August 10, 2022, 04:33:20 pm
content: Quote from: tom66 on August 10, 2022, 12:27:42 pmI meant they don't charge you for power factor. Industrial power meters do. I probably misunderstood the question.

author: Benta
author_rank: Super Contributor
timestamp: August 10, 2022, 06:58:54 pm
content: As a domestic/residential consumer you'll only be billed for real power (kWh). I've never heard of exceptions anywhere in the world to this.That being said, copper losses in your local installation (=after the meter) due to bad power factor will of course increase real power consumption a bit (perhaps 1...3%).Large-scale consumers (office buildings, industry, super markets, shopping malls, server farms) is a different story. They pay for reactive power.

author: nali
author_rank: Frequent Contributor
timestamp: August 11, 2022, 04:40:37 pm
content: To OP: That meter can report both real & reactive, import & export. Mind you what your energy supplier actually charges you for is up to them...If you want to look at devices typically used, take a look herehttps://www.digikey.co.uk/short/0bjhfn8h

author: Zero999
author_rank: Super Contributor
timestamp: August 12, 2022, 01:25:41 pm
content: Quote from: tom66 on August 10, 2022, 12:27:42 pmNo you don't need to know the power factor to calculate kWh.

author: tom66
author_rank: Super Contributor
timestamp: August 12, 2022, 01:33:14 pm
content: Quote from: Zero999 on August 12, 2022, 01:25:41 pmMy point is that you need to measure both V and I continuously, rather than independently, and this is all the information you need to calculate W, VA and PF and numerous other terms. Yes, you do not need to calculate PF to work out W, but you have gathered all of the information required and it's a pretty simple calculation from there on.If you only want to measure VA you can do this by having independent TRMS volt/ammeters on each channel (but I don't think anyone is billed on only reactive power)

author: Miyuki
author_rank: Frequent Contributor
timestamp: August 12, 2022, 02:46:58 pm
content: It is simpleJust look at your billIf it is in kWh/MWh or in kVA/MVA.They are different units for different things.

author: thm_w
author_rank: Super Contributor
timestamp: August 12, 2022, 09:09:07 pm
content: Quote from: Miyuki on August 12, 2022, 02:46:58 pmIts not really that simple, I mean yes for OP we've established they only pay for real power.But for industrial, at least here, you pay real power at the regular rate, then a fee on top of that for average power factor (NOT instantaneous), eg:>90% power factor is 0% fee<50% power factor is 80% feeSo you never get charged in VA.