AVR Freaks

Thank you very much, Lee. This a really useful post, with lots of information.

In brief, we also don't want to use it to bill any energy, but the main use will be double: motor protection in single phase (similar to your posted project, very nice, BTW), and also power consumption/energy metering per hour.

It is intended as a 'gadget' to add functionality to a controller that takes care of a certain machine, that have few different electric motors and different setpoint/adjusts that can affect overall energy saving. Thus not only protect, but also add energy saving functionality.

For a bigger application, where 3-phase motors, we are analyzing the possibility to do all this with a 'number cruncher' that also measure harmonics and waveform distortions, but the idea to use this IC also for a 3-phase is appealing. Can you tell me how do yo do that in 3-phase? Aaron configuration or three different IC's?

The main difference, from what I could see right now between both, is that while ADE has an internal register that counts energy, the Cirrus IC don't have this register, thus one needs an external counter. On the other hand, the CS5463 measures waveform distortion (in power, not in V neither in I), thus no need to do any FFT.

Of course, for harmonics calculation and phase imbalance-assimetry-out of phase in 3-phase systems, there is no way to get rid of FFT.

Anyway, we are still in the study phase, so still not shure about wich exact features we should give to this products. So this is the main reason why I can't tell more about the intended application.

I will also take a look at '7753, or even better, to take a deeper look at AD's web page. Since I'm using some AD's ADC's, I'm quite confident in their quality. That is why my first chance would be their IC, but this depends also on the final requirements.

Thanks for you help.

Thanks for the information, Lee. I still have to take a look at this IC's. Right now, I have a bunch of meetings, 'brainstormings', few documents to finish off, and few other tasks to finsh from other projects that are about to be released (or similar :S). Probably next week I cold take a deeper look at them. I don't know when will be ready to test this chips (and many more), but I expect about Q4, this year.

Right now we are only 'throwing ideas', with few hints about what is in the IC market, and past summer we will probably go further investigating all possible lines. But the fact that AD have some 3-phase products is a major point to us. Probably Cirrus also have some.

The main problem with waveform distortion is that certain motors run warmer, and in our case, this could be a problem, while for resistors and fans, this is not an issue.

Anyway, we still should investigate what kind of electric disturbances are the most problematic, and what protections should we implement. We would worry later about how we implement them. Overheating motors can be protected with a simple temperature probe, or even with a thermostat.

I like AD products. I worked with AD7708 16 bit ADC, also SPI, and it tooks me few days to interface it and make a "driver". It works like a charm, although it has a lot of registers inside. The waveform capture in the ADE would be also a good point, since we can use it as a simple external ADC and perform any waveform analisis through that. The fact that we need a wide dynamic range for the current (from few mA to, perhaps, 20A) to work with the different loads that we would handle is also a good point, since 12 bit would not be enough (and AD7708 would be too slow).

Respect to the price, it seems that both are 'cheap', in the sense that the main cost would be isolate them and other electrical issues. And if we take into account the fact that to do a similar job one needs an external ADC with 16 bits or more (due our dinamic range in current, probably in voltage also), then the price difference becames even smaller.

A pity that this project probably would not be AVR powered (neither Xmega :(). Perhaps certain MIPS based uC? This decission is not in my hands.