Measuring 50Hz signal using interrupt for relay operation

[JACK871]

hey guys i want to measure 50Hz signal by 10 kHz interrupt by which more accurate result i get kindly help.............

 

[udayan92]

If you are using a microcontroller to measure frequency,then you might find this useful...
http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/frequency-measurement/9s12-hcs12-pulse-accumulator-c-example

 

[KlausST]

Hi,

hey guys i want to measure 50Hz signal by 10 kHz

What exactely do you want to measure?
Frequency? RMS voltage? waveform?
With ADC? timer capture?

Klaus

 

[D.A.(Tony)Stewart]

If this is an AC Relay and you are looking for zero crossing sensing then XOR the signal with delayed signal to generate pulse to clock memory cell.

 

[JACK871]

first of all thanks to all of you... i want the perfect value of signal at particular instant so if fault is occurs my 8051 can generate tripping signal.

my relay is working on 12v dc (miniature relay for project) which is turn on and off by 8051 when fault is occurs...

 

[udayan92]

If you want to generate frequency,then you can use the timer/counter in 8051 and use that frequency to sample the input wave.

if fault is occurs my 8051 can generate tripping signal.

Could you give some more details on that..?

 

[D.A.(Tony)Stewart]

first of all thanks to all of you... i want the perfect value of signal at particular instant so if fault is occurs my 8051 can generate tripping signal.

What kind of fault did you have in mind?
What do you quantize as a fault?

how much voltage, current frequency variation is expected? tolerated? Will you relay withstand full surge current on restart? Will be be auto reclose? What criteria? What are you protecting ?

 

[mdvrajkot]

Hello udayan92,

To fulfill your requirement, you will require the zero cross detector circuit at the hardware side & Timer/Counter functions at the software side.

You are saying that your crystal frequency is 10 MHz, which is sufficient for your application.

 

[udayan92]

To fulfill your requirement, you will require the zero cross detector circuit at the hardware side & Timer/Counter functions at the software side.

Correct.
JACK871,please attach the zero cross detector circuit and implement the timer counter functions on the program to get your system working in the correct manner.

 

[KlausST]

Hi,

You are saying that your crystal frequency is 10 MHz

I can´t find this information.


JACK871:
Please give more information. And more detailed.

i want the perfect value of signal

... is no specification.


Klaus

 

[paulfjujo]

hello,

hey guys i want to measure 50Hz signal by 10 kHz interrupt by which more accurate result i get kindly help.............

i did 50Hz 230V AC measurement trough a trafo 230V/9VAC to assume galvanique insulation and some natural filtering.
and measure the 50Hz sinusoide (290 elementary measure within 20mS) to calculate peak to peak value => efficace value..
With taht you can do some action .. put a relay ON if ..some conditions..

if it can inspire you, have a look HERE
Even writen for a PIC 18F

 

[JACK871]

THANX to all of you..
my system is 230v Ac, 50 Hz frequency, and i want to measure current using cts. when i am creating overcurrent or overvoltage fault at that time my project give trip signal to relay.

my maximum current is 15A and when it is reach to 20A it gives trip for overcurrent..

I cant find this peak value for which my microcontroller know its time to give trip signal to relay.

plz also help for programming 8051 with adc for this project..