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# Problem with power factor measurements (ADE7816)

Hi,

we have a problem with ADE7816, we started the design of a new device with multi-input CT, we bought the evaluation board and connected a inductive load at channel A, and we used in parallel a analyzed power to calibrate it....these are the results:

1) we got differents power factors:

Analyzed power(calibrated): 0.850

2) we got this angle by two ways, and get the same result:

ADE7816 method (1)  --> cos(arctg(AVARHR / AWATTHR))=0.985

method (2)  --> directly reading ANGLE0 -->  cos(ANGLE0*(50-360)/25600)=0.995

We don't know what happend but we get different power factor when use reactive load (0.985 =/ 0.85),

it's a big different between these values.

I think this driver (ADE7816) should work well, but we don't know what happend.

Thank you at all.

Parents
• Hi himani,

I am using this reference meter:

http://www.ndmeter.co.uk/files/Rail_350_Meter_Leaflet_Jan2012.pdf

we use this meter before and I think it's accurate, up 30th armonic to 50Hz.

Today I have changed the load and now PF=0.87, as you see in the picture that I attach you.

I attach you other picture with the jumper configure of current input (channel A) and voltage.

There is a big error between these results  (reference meter =0.87  //  ADE7816(channel A)=0.98),

I have tried to do other exercises to solve that problem,

-I tested other channel, with the same result.

-I tested other load, same error

-I checked CT, and I'm sure that doesn't introduce that error.

• * write WTHR1=0x02
• *write VARTHR1=0x02
• * after several minutes read AVARHR & AWATTHR to calculate PF

with these initial values and start DSP, AD7816 start to accumulate active and reactive, but with a error so big.

What am I doing wrong? What do you think?

• Hi himani,

I am using this reference meter:

http://www.ndmeter.co.uk/files/Rail_350_Meter_Leaflet_Jan2012.pdf

we use this meter before and I think it's accurate, up 30th armonic to 50Hz.

Today I have changed the load and now PF=0.87, as you see in the picture that I attach you.

I attach you other picture with the jumper configure of current input (channel A) and voltage.

There is a big error between these results  (reference meter =0.87  //  ADE7816(channel A)=0.98),

I have tried to do other exercises to solve that problem,

-I tested other channel, with the same result.

-I tested other load, same error

-I checked CT, and I'm sure that doesn't introduce that error.