3 phase mains power meter  - Page 1
Forum section: electronics / testgear

author: Swake
author_rank: Frequent Contributor
timestamp: February 10, 2017, 05:52:02 pm
content: Hi all,Want to know what the electric consumption is in different parts of the house. And want to record it in some kind of database.Must have:3 phase (mains is 3phase + Neutral 40A/400VAC)- Cumulated consumption (kWh)- Instant consumption (W)- Some computer grade interface with the outside world, in order of preference: Ethernet, Wifi, serial, rs486, USB, RF- Not too expensive as I probably want 3 or even 4 unitsNice to have- per phase measurement- Voltage and amps measurement- Cos-Phi- Low consumption- Good accuracyExtra fun- Fancy display or web interface- High resolution (would enable identification of the device that is switched on or off)- Any additional measurement- Energy Cost calculationI consider buying a couple of these cheap meters on ebay and aliexpress (+ adequate current probes + a RPi or some other board.)http://www.ebay.com/itm/122201038416http://www.ebay.co.uk/itm/Intelligent-Digital-Display-Three-phase-Multi-function-Network-Meter-Ammeter-/262564100199https://www.aliexpress.com/store/product/Intelligent-Digital-Display-Three-phase-Multi-function-Network-Power-Meter-Ammeter-Free-Shipping-12003222/204613_32711841037.htmlWhat do you think? Do you have experience with these meters?I did consider several solutions including some diy things, but for the price of the above.....

author: _Wim_
author_rank: Super Contributor
timestamp: February 10, 2017, 09:00:36 pm
content: You could have a look at some of the devellopmentboards from Microship:http://www.microchip.com/DevelopmentTools/Listing.aspx?CatID=f99a0ef5-7835-4a8f-b863-f430c580323fI have a single phase board, build quality is really nice.

author: Unknown
author_rank: Unknown
timestamp: February 10, 2017, 09:09:11 pm
content: Apologies in advance for being off topic, but, is three phase power common in residential settings outside the US?Within the US I have very rarely seen three phase outside of commercial settings. Some extremely large houses or farms may have it for running large motors or farm machinery, etc. but almost all residential power is 1 phase 2 pole (i.e. one 240V phase split into two 120V poles from a center tapped transformer, with a ground bonded neutral).I looked into bringing 3ph 480V to my property which astounded the local electricians and permitting folks, despite the property being quite rural. The reasoning was to be able to take advantage of surplus 3ph generators for backup power (with a decent transfer switch, of course), and to reuse the existing buried utility feed without having to replace it with large gauge wire.After the steam stopped blowing from their ears it worked out to that the 480V had to stay outside on a pad mount transformer and it had to be stepped down to 208V wye entering any residential structure. I think I eventually found the National Electrical Code justification for that. However I do see a lot of talk about residential three phase and sometimes higher voltages as well, in other countries.In regards to the original topic, since the goal is data logging, have you looked into installing ModBus enabled 3 phase power meters or branch circuit monitoring? Schneider Electric, for example, makes a variety of models for such things. The ModBus interface is fairly easy to gather data from on your own (RS-485 serial and can be gatewayed to IP/Ethernet).

author: Swake
author_rank: Frequent Contributor
timestamp: February 10, 2017, 09:43:26 pm
content: Those el-cheapo things have a modbus over rs485 interface too.And thanks for the tip about the Schneider electric meters. Model PM5110 (METSEPM5110) looks good and has modbus over rs485. It costs 3 times more though. Might be worth it. Better brand, better support, higher resale value...About the off topic question: In Belgium and in the Netherlands 3phase/4wire 230/400V is quite common, and I believe in Germany as well. Not sure about other European countries. In and around Brussels 3phase/3wire 230V is also common system. In older houses the connections are rated 16A or 25A. Though I recently saw an old 3phase 10A connection in Brussels. In moderner homes (up to 25y old) you'll commonly find 32A or 40A 3-phase connections. New single family buildings are generally equipped with single phase now, often 64A, sometimes 40A.

author: 128er
author_rank: Regular Contributor
timestamp: February 10, 2017, 09:54:41 pm
content: Hi Swake,at work I use these Siemens Sentron PAC3200/4200 very often. They require current transformers. But have all the fancy functions you want.Must have:3 phase (mains is 3phase + Neutral 40A/400VAC)CHECK!- Cumulated consumption (kWh)CHECK!- Instant consumption (W)CHECK!- Some computer grade interface with the outside world, in order of preference: Ethernet =CHECK!Modbus TCP Protocol- Not too expensive as I probably want 3 or even 4 unitsNOT REALY CHECKNice to have- per phase measurementCHECK!- Voltage and amps measurementCHECK!- Cos-PhiCHECK!- Low consumption~6W- Good accuracyAlso depending on the current transformer usedExtra fun- Fancy displayCHECK!or web interfacePossible!- High resolution (would enable identification of the device that is switched on or off)Nah, maybe. Depends also on other factors- Any additional measurementThe devices have Digital IO. It's possible to read out gas flow meters or other devices with impulse output.- Energy Cost calculationMuste be done externalyhttps://mall.industry.siemens.com/mall/en/de/Catalog/Product/7KM3133-0BA00-3AA0With bit of luck you can get these cheap on Ebay.You can also look for Janitza, EMU Energy or Bender. And I bet there are a dozen other manufacturer. And the usual chinse ones for sure.

author: Assafl
author_rank: Frequent Contributor
timestamp: February 10, 2017, 10:10:43 pm
content: I use a Socomec DIRIS A40.http://www.socomec.com/range-single-circuit-multifunction-meters_en.html?product=/diris-a40_en.html&view=option#optionMine doesn't have the Web server feature installed (got it for really cheap on eBay).Used it for balancing the 3 phases so we could stick with 3x25A and not have to upgrade to 3x40A.

author: Unknown
author_rank: Unknown
timestamp: February 11, 2017, 01:18:14 am
content: Quote from: Swake on February 10, 2017, 09:43:26 pmAh, interesting. Thanks! I wish it were as common here. It would certainly give better options for things like HVAC loads. Do people have issues with arc blast on the 400V in residences?Quote from: Swake on February 10, 2017, 09:43:26 pmNo problem! Personally I would also feel a bit more comfortable with the name brand stuff at 400V.

author: james_s
author_rank: Super Contributor
timestamp: February 11, 2017, 01:21:31 am
content: I envy those who have domestic 3 phase power, although with modern electronics it isn't as big of an advantage as it used to be. I have several 3 phase induction motors that I run at home using cheap VFDs that don't care whether the input is 3 phase or single phase. As an added bonus I get variable speed.

author: Gregg
author_rank: Super Contributor
timestamp: February 11, 2017, 03:05:39 am
content: Veris industries makes high quality and reliable power monitoring equipment and a bunch of really neat stuff like current transformers that have integral settable switches and ground fault devices. They are also nice people and you can talk to a real engineer instead of a sales person if you request same.http://www.veris.com/Category/Current-spcMonitoring.aspx

author: Gregg
author_rank: Super Contributor
timestamp: February 11, 2017, 03:16:13 am
content: Another one I just thought about: E-Mon D-Monhttp://www.electricsubmeter.com/emon-dmon/index.htmI have used these for sub metering 3 phase power in large office buildings where the tenant was billed for their use from the main building metered power rather than having to add another service. They are pretty much self contained and available in lots of configurations.

author: David Hess
author_rank: Super Contributor
timestamp: February 11, 2017, 04:24:55 am
content: Quote from: Elf on February 10, 2017, 09:09:11 pmWhat was the nanny state's rationalization?

author: Unknown
author_rank: Unknown
timestamp: February 11, 2017, 11:44:45 am
content: Quote from: David Hess on February 11, 2017, 04:24:55 amJust looked over my old 2011 copy of the NEC, and of course, now that it is a few years later I can't find anything that looks directly relevant anymore. NEC 210.6a (120 volt maximum) only covers "luminaires or cord-and-plug connected loads," and 210.6 in general only seems applicable to branch circuits, not feeders. I guess it would prohibit using 277V lighting in a dwelling. At the moment the only thing I can find similar to a voltage limit is the Canadian Electrical Code 2-106 (150 volts to ground maximum in a dwelling), which I wouldn't think applicable in Washington State, or NEC 690.7d (no accessible circuits over 150 volts to ground for solar photovoltaic systems). Of course a lot of the NEC language around feeder requirements in dwellings also is worded to assume 120/240 or 208V wye.There are all sorts of state and county administrative rules on top of the NEC, so who knows. If you go looking there are plenty of funny things, like NEC 600.32i specifically prohibiting neon signs in dwellings. "Neon Secondary-Circuit Wiring, over 1000 Volts, Nominal [...] Equipment having an open circuit voltage exceeding 1000 volts shall not be installed in or on dwelling occupancies."Looking back at my notes I was told "no more than 250 volts in a dwelling." Their explanation was that they thought the average homeowner was incapable of dealing with 480V and would go opening up panels and dropping screwdrivers across bus bars.

author: David Hess
author_rank: Super Contributor
timestamp: February 11, 2017, 01:29:10 pm
content: Quote from: Elf on February 11, 2017, 11:44:45 amThey sounds like the kind of things they would come up with to prevent people from doing business activities in their homes. Everything which is not allowed is forbidden.

author: PaulAm
author_rank: Frequent Contributor
timestamp: February 11, 2017, 03:10:36 pm
content: This probably doesn't help you a lot, but I just recently picked up a couple of ACM 3710 power meters. They're about lunchbox size with a vfd display. They do everything you need and can send data over an rs-232 line. I paid $15 US ea for them. They were used pulls, probably from some generator installation. They can handle up to 5A directly, over that you need current transformers. They were sold as-is but appear to be 100% functional.Keep an eye out for a similar deal. In a commercial situation there will be periodic hardware refreshes and the old meters aren't worth much.

author: Swake
author_rank: Frequent Contributor
timestamp: February 12, 2017, 04:45:07 pm
content: Thanks for all those different brands en models.Will probably go for the Siemens or Schneider thing.

author: Jeroen3
author_rank: Super Contributor
timestamp: February 12, 2017, 08:06:47 pm
content: There are also pQubes. Which we use occasionally to find problems.http://www.powersensorsltd.com/PQubeThey do however fail your "not too expensive" point on the checklist. They're about 3k.I do know cheap modules are not accurate. 3 phase is hard, especially when you're on the consumer side.

author: capsicum
author_rank: Contributor
timestamp: February 12, 2017, 09:08:27 pm
content: Each phase is generally measured separately. An induction coil around each phase conductor to measure current, I've been awake 20 hours so I forget how the figure the voltage portion phase-phase or phase-ground. For larger consumers, power factor[phase shift] is also considered and penalized by power companies so that they don't cause issues on the main grid.(residential loads are traditionally very resistive so wash out most induction before it gets back to the grid, so power factor isn't calculated in billing.)Factories using large motors and induction process heating are the main source.

author: Assafl
author_rank: Frequent Contributor
timestamp: February 13, 2017, 12:05:41 pm
content: Quote from: Jeroen3 on February 12, 2017, 08:06:47 pmI don't know - cheap stuff can be fairly accurate. The Socomec DIRIS A40 are 0.2% on TRMS current and 0.2% on voltage. Not in the Fluke Power Quality analyzer ranges (0.1%) but good enough for household use).http://www.socomec.com/range-single-circuit-multifunction-meters_en.html?product=/diris-a40_en.htmlThey are not cheap when new (generally $800 or so with $400 for the Ethernet module), but I consider it cheap as so many of them are on eBay for less than $100. I bought a used one in 2015 for $50 + $16 shipping. At the time, I just searched eBay for an industrial 3~ monitor and acquired the cheapest. It replaced an inexpensive Hobut 3~ power meter which failed after 3 years due to incorrect wiringhttps://www.hobut.co.uk/power-meters/m850-multi-function-metersThey are also a bit over the top (harmonics analysis, tons of VA and PF analysis, kWh counters, and other - mostly useless - crap) - but I liked it because it gives me peak current and peak power consumption so I was able to monitor and balance the phases and check out power hogs.

author: coppice
author_rank: Super Contributor
timestamp: February 13, 2017, 12:29:16 pm
content: Quote from: Jeroen3 on February 12, 2017, 08:06:47 pmThe pQube is expensive because its a full power quality analyser. A 0.5% accurate 3 phase power meter, displaying the basic set of RMS voltage, RMS current, active power, reactive power, power factor, frequency, and so on is a $50 product. A 0.2% one isn't that much more these days. Prices have been driven down my the huge volumes these things are made in for utility metering.

author: Jeroen3
author_rank: Super Contributor
timestamp: February 13, 2017, 03:20:54 pm
content: The difficulty is in making the three phase current en frequency measurement work reliabably and accurate over the entire range. Current has a lot of high frequency stuff at the consumer side. Which makes it hard.I've build a meter before. Not something you "simply put together with little money and effor".Those socomec look nice. Especially the Diris A17 which shows you the actual quadrant. Instead of +/- ambiguity.*if anyone knows some 0-500hz 0-400v 96mm frequency meters, please let me know.*

author: Swake
author_rank: Frequent Contributor
timestamp: February 14, 2017, 07:48:20 pm
content: Ordered a nice Siemens Sentron PAC3200. There is an Ethernet port on this thing and that makes things much more easy.I'll have to learn about modbus I guess

author: 128er
author_rank: Regular Contributor
timestamp: February 14, 2017, 08:14:32 pm
content: Have fun with it!I've never tried to read out my PAC4200 with some sort of custom made piece of software made by myself. I've done it with the Siemens visualization tool WinCC, that was pretty easy. But it costs a lot. I wonder if there is a free library for CODESYS by 3S. CODESYS is partially free.

author: Unknown
author_rank: Unknown
timestamp: February 15, 2017, 06:20:36 am
content: Quote from: Swake on February 14, 2017, 07:48:20 pmThankfully there is not much to it! For this sort of application, you would usually just be reading from registers.Generally each device has something called a "modbus point map" supplied by the manufacturer which describes the register locations and their purpose / format. For example for the PAC3200, on pp40, section 3.9.3 of the manual (http://w3.usa.siemens.com/us/internet-dms/btlv/access/access/Docs/SENTRON_pac3200_manual_ul_PSC_en.pdf).I have used the jamod library in the past, a Java modbus TCP library (http://jamod.sourceforge.net/). Your language of choice may have something similar. If not, the protocol is simple enough to write to on the wire yourself, and I believe Wireshark (https://www.wireshark.org/) has built in decoding which can help you debug anything that might be going wrong with the communication.

author: gmb42
author_rank: Frequent Contributor
timestamp: February 15, 2017, 12:30:21 pm
content: Modbus is often known as the lowest common denominator in the SCADA world, but unfortunately there are quite a few variations that can trip up someone unfamiliar with it.The protocol specs are available from the Modbus Organisationhere. Using a library for the actual protocol will make things easier for you (assuming the library is OK).The device spec indicates most values are 32 bit floats and are held in two registers, it doesn't say the format of the float, these are usually IEEE754, and which endian the 2 16 bit parts come in. Modbus originally used big-endian, but some vendors use the native endian of the device and then sometimes you get little-endian. Hopefully your library allows you to set the order, or you'll have to read both registers and combine together in the correct order to form the single-precision float for your host. Similar endian issues can occur with the long (32 bit integers) values.Another common issue is register offsets. The protocol on the wire uses 0-based offsets, the "programmers" tools to configure Modbus devices originally used 1-based offsets, and ever since vendors have been mixing and matching which one is used. The device spec seems to show 1-based offsets, but does show those in the context of the protocol functions to read and write so might be showing protocol offsets. The spec does say that if you try to read the "second" register of the pair you get an error so that should be easy to discover.Wireshark does a reasonable job for Modbus TCP but can only show all registers in a fixed format, by setting a preference, i.e. you get all longs or all shorts or all floats.