Measure power factor using 89c51

[lats]

measuring power factor

Hi friends,
i trying to measure power factor using 89c51 but the results are not stable. i simply started timer on first interuppt and stopped on second and then caculated, but the results aren't too good. i mean they are not too stable some times they show proper value sometimes wrong.
can anyone please share some code for the same.

Thanks

With best regards.

 

[nandhu015]

how to measure power factor

Hai

As far as i know measuring power factor is not an easy job.

And further more 89c51 is not suitable for that job.

Nandhu


Here is something i found on another forum
https://avrfreaks.net/index.php?nam...r+factor&sid=58b096183ad3eb0385ad108f9725fb83

 

[pravin_dwaramwar]

measure power factor

Dear friend will u tell me ur scheme of calculating PF.
then only i can help u.

 

[sawaak]

microcontroller power factor

Hi,
check the following post




thanks
sawaak

 

[muoinhohn]

measuring power factor microcontroller

Hi lats,
How do you calcul power factor with 89C51? If you describe your problem in detail, then people in the forum can help you.
I think if you measure simply in detecting the zero cross of I and U , after calcul the duration, then PF is not correct.
Regards
Muoinho

 

[roykyn]

power frequency zero crossing

one simple method of finding the power factor is by using pll......
check cd4046 IC .....

 

[jayavardhan]

power factor microcontroller

As far as i know measuring power factor is not an easy job.

donot use normal timers use a timer which is having a PWM mode.

 

[lipeng]

measure power frequency

use a small dsp

 

[muoinhohn]

measuring power ic

You can use 89C51 incorporate with ADE77xx (7753 , 7754...) of Analog Devices.
Regards

 

[lats]

measuring power factor: problems

lipeng can u please guide me which small dsp can i use.

muoinhohn, few month back i tried lot interfacing ADE7754 with 89c51 but wasn't able to do it. can u share some code regarding the same.

Thanks all of you

 

[watermelon]

50hz counter with 89c51

I guess, the problem is that there are

(a) Initial errors due to the analog hardware etc. causing phase shift, error in zero crossing etc. leading to repeatable errors which can be nulled by calibration.

(b) The frequency is not always 60/50 Hz, it varies.

(c) Noise and interference.


I'd suggest :

(a) Get the current sample, filter (amplitude limiting is also required) and use a zero crossing detector to get a zero pulse on rising (or falling) edge.

(b) Do the same with voltage.

(c) Use the interrupts on the microcontroller to count the phase, i.e. start with voltage zero and end with current zero, continue counting till the next voltage zero, this gives you the 360 degrees of the voltage (indicating exact frequency). Phase error due to power frequency changes will be small and may be ignored unless you want higher accuracy (than normal), in that case, calibrate for each increment / decrement of 1 or 2 Hz..

(d) Divide phase count by frequency count. First calibrate with known zero phase shift (at the specific power frequency) and find the error. Ensure that nothing heats up.

(e) From each count subtract the error in real readings. Integrate over 16 or 32 samples to get an average value.

The counter frequency should be sufficiently high to provide the required resolution. You could use 60 (or 50) X 256 (8 bits, but keep the counter as 16 bits in case of decrease in power frequency) = 15,356 Hz. 8051 and derivatives have no problem at this count rate.

Use noise / RFI filtering and enclose everything in an earthed metal box. Use very good grounding.

This worked 10 years ago.

 

[watermelon]

measuring power factor

Of prime importance is ensuring that interference, high voltage, spikes, current surges etc are removed. This requires good signal conditioning and careful designing.

I guess, sampling once every second and using a window filter of 32 samples should be sufficient. Surges due to heavy machinery start / stop / load / unload range from 2 to 15 seconds. Filter length and sampling rate can be modified to suit various needs.

I hadn't tried median or modal filters, but these could be easy to implement in software.

 

[mg_designs]

how do i measure power factor

i measure power factor with ade7754 the result was very good

 

[Prabakaran]

how to measure power factor?

Measuring The Power Factor is not So easier Thing.

Better Go for Accuracy Meter ADE7753 which is single Phase Power Meter IC .
In That measure the Watt and VA energy wit those parameters calculate the Power factor. But ADE7753 supports SPI protocol to access the data from that. Better GO for AT89S52 which supports the SPI protocol .

 

[hulahula]

measuring power in microcontroller

**broken link removed**

 

[svaidy]

power factor measurement mcu

Please tell the circuit for power factor measurement for 1-phase circuit. and please give the circuit diagram and codings for microcontroller. This will very helpful to our project.

thanking you,

with regards,
S.Vaidyanathan,
srivenkatraman@gmail.com

 

[nandhu015]

89c51 rising edge interrupt

Please tell the circuit for power factor measurement for 1-phase circuit. and please give the circuit diagram and codings for microcontroller. This will very helpful to our project.

thanking you,

with regards,
S.Vaidyanathan,
srivenkatraman(at)gmail.com

Why are digging 2 yrs old thread.

Why dont you start a new topic?

Nandhu

 

[madicalphy]

for further information on the subject of the post, check this link and find suitable information.
**broken link removed**