Power measurement ICs: Search Term needed and suggestions welcome - Page 1
Forum section: electronics / beginners

author: schwarz-brot
author_rank: Regular Contributor
timestamp: November 24, 2016, 12:41:49 pm
content: Hi folks,I am a bit stuck on what to search.I need to measure line power in a pretty detailed way (a 230V, 50Hz system that is), allowing for detailed analysis via a µC. First option would be using the µC directly via a shunt or hall effect sensor. But maybe there are specialized ICs out there to do this for me? I get the feeling I simply don't know what to search for.Thank you!Jan

author: bktemp
author_rank: Super Contributor
timestamp: November 24, 2016, 12:46:10 pm
content: You are looking for energy metering ics.http://www.analog.com/en/products/analog-to-digital-converters/integrated-special-purpose-converters/energy-metering-ics.htmlhttp://www.nxp.com/products/power-management/energy-measurement-ics:MC_71789http://www.microchip.com/wwwproducts/en/MCP3909http://www.silergy.com/products/electricity_metering_icsSome ics contain only multiple adcs, but others do also the full power calculation.

author: nfmax
author_rank: Super Contributor
timestamp: November 24, 2016, 12:58:02 pm
content: You can get DIN-rail mounting metering modules which measure current & voltage and give a pulse output, e.g. 1000 pulses per kW-hr. The pulse output is isolated from the supply. They can be pretty cheap. For examplehttp://uk.rs-online.com/web/p/digital-power-meters/8718302/

author: DTJ
author_rank: Super Contributor
timestamp: November 24, 2016, 01:05:43 pm
content: TI make some MSP430's targeted at that sort of application.Maybe:http://www.ti.com/product/MSP430F67791A/toolssoftware

author: Yansi
author_rank: Super Contributor
timestamp: November 24, 2016, 01:31:34 pm
content: ST Also makes some MCUs targeted for such applications:http://www.st.com/en/microcontrollers/stm32f373.html?querycriteria=productId=LN10

author: coppice
author_rank: Super Contributor
timestamp: November 24, 2016, 01:32:32 pm
content: Quote from: schwarz-brot on November 24, 2016, 12:41:49 pmHow detailed? What parameters do you need to measure? A number of people produce black box ASIC devices specifically for measuring mains power and energy (ADI, Cypress, etc). Several people make MCUs with suitable ADCs, so software can be used for a more flexible approach to measurement (Ti, NXP, etc). Some make a MCU with a largely fixed function measurement block (Silergy, Toshiba, etc). If you really want flexibility you might need more horsepower from the CPU (e.g. power quality measurement to IEC61000-4-30). Atmel's dual core M4 + ADCs device for the metering market might give you enough performance, or you might need to look at a faster processor and a separate front end.

author: schwarz-brot
author_rank: Regular Contributor
timestamp: November 24, 2016, 02:07:45 pm
content: Alright,seems like more information is needed. I want to measure or calculate all kinds of power: active, reactive, complex and have a special interest in deformed power. Would be great if I could derive the current waveform for further analysis. I don't care about the voltages waveform as I expect them to be pretty stable. I know this ain't always true but I'll leave that for a possible later iteration. I don't mind sending data off to a PC or log on a sd card, this will most probably happen anyway. If doing so I might as well simply take the waveforms and do anything later.I already searched the usual suspects before posting here. Power metering IC and energy metering IC being my search terms. I was overwhelmed by the sheer number of hits and thought I might have been wrong because it seemed I only found those devices catering to simple power meters, returning pulses or maybe analog readings.This all may seem a bit confused. Don't worry - I have not yet settled on the way I want to tackle this.Thank you all, for your quick replies. Further comments are of course welcome.

author: coppice
author_rank: Super Contributor
timestamp: November 24, 2016, 02:14:26 pm
content: Quote from: schwarz-brot on November 24, 2016, 02:07:45 pmYou can see 20% THD on a mains voltage waveform, especially in industrial areas. I've seen voltage THD vary between 2% and 20% between the ground floor and high floors of a single tower. That will reflect in the current waveform, even for a simple resistive load, like a water heater. Therefore, looking at the current waveform in isolation from the voltage waveform doesn't make a whole lot of sense.

author: nfmax
author_rank: Super Contributor
timestamp: November 24, 2016, 03:36:36 pm
content: How about these?http://www.sentec.co.uk/our-technology/micromonitor

author: coppice
author_rank: Super Contributor
timestamp: November 24, 2016, 03:51:06 pm
content: Quote from: nfmax on November 24, 2016, 03:36:36 pmThey look a bit crude compared to the competition. They can't interface directly to a shunt for one thing, and their accuracy is not very good. For some users the use of a UART output could be a big benefit over the SPI output of most ASICs. However, Atmel has ASICs with a UART interface which can directly interface to a shunt. This is a business Atmel bought from IDT, so you might find information about the same devices with IDT's name on it.