Hi,

I am using ADE7816 along with the EVB. I want to get the rms values of voltage and current for every 2ms. I had some questions regarding this :

In the user manual, you mentioned :

The ADE7816 provides rms measurements on the six current channels and the voltage channel simultaneously. These measurements have a **settling time of approximately 440 ms** with the integrator off and 500 ms with the integrator on. The **registers are updated every 125 μs**. The rms value is measured over a **2 kHz bandwidth**.

a) What is the 2KHz Bandwidth ?

b) Are the rms registers update for every 125us ? If yes how was the caluculation of rms done ?(done using instantaneous samples ?(how many and how much duration ?))

c) What do you mean by settling time ?

Thanks&Regards

RMS is not just a dc measurement. RMS is calculated based on our ADC samples and our ADC has a 2k bandwidth so if you had a 2k sinewave with no noise you will get the RMS of that frequency. If you had DC and a 2k signal + noise you would get the RMS of the DC to 2Khz spectrum.

RMS is updated every sample continuously. This is a filtered output so some setting is required. If you change your input value from say .1v to .2v it will take 440ms(integrator off) to settle to the datasheet specs for RMS accuracy. What is your accuracy requirement? You can read RMS every 2ms the reading my not reflect your input to datasheet accuracy until 440ms later.

RMS = current sample ^2 --> lowpass filters ---> SQrt

The low pass filter contains previous sample ^2 data this is why the settling time.

Dave