Home Appliance Testing/Recording Meter - Page 1
Forum section: electronics / projects

author: mukulkhairatkar
author_rank: Contributor
timestamp: January 07, 2011, 07:09:25 pm
content: Hello All,I am working on a Home appliance product which is almost finished. I need to record Voltage/Current/ Power and frequency for 24 hr cycle time. This data will be further used to optimized the system performance. Can you suggest my any meter or a device which I can hook up to the appliance and record all these parameters? The power requirement is 110V/60Hz/10A.Any other method I can achieve this?Thanks in advanceMukul

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 07:20:37 pm
content: the simplest method would be an MCU that can interface to a pc to store the data with (that if your better at that sort of thing than me) current sensing circuitry attached to the MCU to get the signal into a 0-Vdd range

author: mukulkhairatkar
author_rank: Contributor
timestamp: January 07, 2011, 07:26:16 pm
content: I found this... But it is only in Australia.....I need one for USAhttp://www.fluke.com/fluke/auen/Portable-Appliance-Tester/Fluke-6000-Series.htm?PID=56095Mukul

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 07:37:13 pm
content: and i hate to think how much it costs

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: January 07, 2011, 07:46:21 pm
content: It's about $1,700 US

author: saturation
author_rank: Super Contributor
timestamp: January 07, 2011, 07:54:30 pm
content: Yes, you need a power meter with data logging.There are professional ones [ capable of multiphase], and semi-pro ones [ single phase such as linked] and consumer ones, both with and without logging. The specs of any of these will meet your needs, they are built for US style branch circuit loads of 15A or less.Here's one type:http://www.powermeterstore.com/p1206/watts_up_pro.phpThe above is $130.http://www.amazon.com/Arbor-Scientific-Watts-Up-PRO/dp/B001MU7VFE/ref=sr_1_5?ie=UTF8&qid=1294429589&sr=8-5There are 3 variants, non-logging, downloadable logging and real time.Please review it for us if you get it; I have a non-logging version that I got for $20. I also confirmed its readings by double checking the device's measurements using a DMM.Quote from: mukulkhairatkar on January 07, 2011, 07:09:25 pm

author: saturation
author_rank: Super Contributor
timestamp: January 07, 2011, 08:05:31 pm
content: As an aside, since I bought a power meter, I've reduced my electric bills a minimum of 25%, at times as high as 50% from what I paid before. It really showed the inefficiency of some devices and small things you can do that are inconsequential that make a difference.For example, when I create a temporary server for shifting data between work and home I used to use my c2007 desktop; it consumes 100 watts on, 150 watts with the monitor on. By switching to my laptop to do the same, my consumption is now 20w. 1 W when the laptop sleeps but wakes when accessed.By putting a timer on my water heater to shut it off when I'm not home, I instantly reduced my bill by $10/mo.By replacing 10W night lights and CFL bulbs with small LED based socket-plugs it consumes not even even 1/100 W-hour.I gave my brother such a device, and he changed his refrigerator as a result. The refrigerator went from $50/mo in kwh costs to $50/year!! That's amazing.

author: mukulkhairatkar
author_rank: Contributor
timestamp: January 07, 2011, 09:12:44 pm
content: Thats what exactly I wanted....Thanks a lot.I am still wondering how can I get the Fluke meter. I checked on the USA website and could find the category for such meter, but if I go to AUS site, they have it thereanywys.....will be getting this one in coming daysThanks a tonMukul

author: GeoffS
author_rank: Unknown
timestamp: January 07, 2011, 09:30:52 pm
content: Have a look atDranetz, they specialise in power management and monitoring.Not a cheap solution though.I can remember some years back having power problems with a computer installation. They installed a monitor from this company and it recordedeverythingabout the mains supply for a week. [Problem was very brief power spikes in the early hours of the morning and the monitor caught them all.]

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 10:08:50 pm
content: Quote from: saturation on January 07, 2011, 08:05:31 pmI pretty much know the power consumption of everything in my house and will make sure I run everything as economically as possible. Unfortunately I don't have the money to change my fridge should I find it to be expensive to run but I'm paying £35 a month for both electric and gas

author: saturation
author_rank: Super Contributor
timestamp: January 07, 2011, 10:23:34 pm
content: You could get some free power savings by checking the cooling coils are well ventilated and free of lint. If you had a power meter you could see the change in kwh instantly, but barring that, its a simple fix.Quote from: Simon on January 07, 2011, 10:08:50 pm

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 07, 2011, 10:52:59 pm
content: Quote from: saturation on January 07, 2011, 07:54:30 pmi would love to have this cheapy one, when i need the data logging, maybe i can find a way to hack to see how it read the V and A.

author: Zyvek
author_rank: Regular Contributor
timestamp: January 07, 2011, 11:09:06 pm
content: Quote from: shafri on January 07, 2011, 10:52:59 pmYou can find some info here:http://www.ladyada.net/make/tweetawatt/

author: Chasm
author_rank: Regular Contributor
timestamp: January 07, 2011, 11:11:11 pm
content: Data logging power meters are nice and not that outrageously expensive any longer.But for development of appliances better take a close look at the regulations. I'm sure that they specify what accuracy you need.

author: saturation
author_rank: Super Contributor
timestamp: January 07, 2011, 11:28:16 pm
content: Hi Safri,You are in Malaysia I recall? This is a rebadged Chinese model you may be able to find there easily.http://www.alibaba.com/product-free/111363378/Kill_a_Watt_EZ_Power_Usage.htmlBasically it uses bare thick copper wire as a milliohm resistor and measures the voltage drop across it, this measures the RMS AC current; then the rest are calculated based on a voltmeter RMS reading of the mains voltage. It has a small MCU to do the calculations and make the conversions, it also detects the power factor due to inductive loads, and since the voltage and current can be out of phase.http://www.lelong.com.my/energy-saving-power-consumption-meter-monitor-43320708-2009-09-Sale-P.htmChasm, I think these are about 0.2%, 1% tops; mostly its tied to the accuracy of the voltmeter section.Quote from: shafri on January 07, 2011, 10:52:59 pmQuote from: Chasm on January 07, 2011, 11:11:11 pm

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 07, 2011, 11:35:43 pm
content: thanx guys (saturation and zyvek) the links are just what i have/question in mind.

author: Chasm
author_rank: Regular Contributor
timestamp: January 08, 2011, 12:46:49 am
content: Quote from: saturation on January 07, 2011, 11:28:16 pmI though mostly about stuff like "must use calibrated" or similar things in a standard.Accuracy may change greatly with load. The cheap one I have here:5 - 3500 W (± 1% + 1 count)2 - 5 W (± 5% + 1 count)< 2 W (±15% + 1 count)

author: saturation
author_rank: Super Contributor
timestamp: January 08, 2011, 12:26:29 pm
content: Thanks Chasm, the cheapo I use linked below won't read below 1W. I've measured RMS current on various devices below 10W its well within 1%. FWIW, 10W translates to about $10-15/year to run if left on 24 hrs/day x 365 days, and at 1 W, its $1 1-$2/year. But the need for greater accuracy is to meet government regulations such as Energy Star requirements if your a pro, for non-pro use a 'ball park' figure is good. The government specifies the conditions of testing and the quality of gear to use.In the USA, the EPA has standards for testing various appliances:http://www.energystar.gov/index.cfm?c=partners.enhanced_test_verificationFor a dishwasher, for example:3.5 Watt-hour meter. The watt-hour meter must have a resolution of 1 watt-hour or less and a maximum error of no more than 1 percent of the measured value for any demand greater than 50 watts.But, for chargers or low power i.e., DC run apparatuses, the measuring device must be down to 0.1%.http://www.energystar.gov/ia/partners/downloads/mou/Required_Test_Methods_for_EPA_Recognized_Laboratories.pdfQuote from: Chasm on January 08, 2011, 12:46:49 am