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[PIC] implementing power meter

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burrow

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Hai
Iam pretty new to pic's Adc features. For my next project I need to implement some adc. My requirements are
1) measure a voltage in the range 0 to 30volt dc
2) measure another voltage in the range 0 to 320 ac
3) measure current. In the range 0 to 20 amps
4) track actual power in the second line

I need to measure all 4 together. . Which microcontroller is best for this application?

Also is their any sort of ic that will be measure this and talk to mcu via i2c or any interface?
 

milan.rajik

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Only some PICs, I think PIC24s do simultaneous ADC measurements. Generally PICs have multiplexed ADC. So, only one channel is read at a time.
 

burrow

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Okay... and yea precision is not a concern for me. Power meter is optional too.
Even multiplexed monitoring is going to be okay.
 

milan.rajik

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Use PIC18F. If you need just 4 ADC channels then use PIC with less pin count like PIC18F26K22.
 

KlausST

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Hi,

Is 3) ampere DC, AC peak or AC RMS?

While DC is relatively simple... AC is not. With AC you need continous sampling with a fixed sample rate. Both Voltage and current.
Then you have to decide wether you want to calculate apparant power or active power...

Klaus
 

asdf44

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Well specify the sample rate you need on each one. Multiplexing shouldn't be a problem unless you're bumping up against a sample rate requirement.

There is also going to be some design work to condition these signals for measurement by the PIC.

Do you know how you're going to measure the high voltage AC and 20A signals? It's not trivial.
 

burrow

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Hi,

Is 3) ampere DC, AC peak or AC RMS?

While DC is relatively simple... AC is not. With AC you need continous sampling with a fixed sample rate. Both Voltage and current.
Then you have to decide wether you want to calculate apparant power or active power...

Klaus
i want to measure AC RMS. i suppose ac rms is used to measure active power.

- - - Updated - - -

Well specify the sample rate you need on each one. Multiplexing shouldn't be a problem unless you're bumping up against a sample rate requirement.

There is also going to be some design work to condition these signals for measurement by the PIC.

Do you know how you're going to measure the high voltage AC and 20A signals? It's not trivial.

to be frank i dont know how.. iam starting from scratch.. :)..currently reading some articles on implementing adc
 

FvM

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i want to measure AC RMS. i suppose ac rms is used to measure active power.
Nope. To measure active power, you'll multiply instantaneous values of I and V and average the product.
 

burrow

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Nope. To measure active power, you'll multiply instantaneous values of I and V and average the product.
Oh i see. thanks for the information.
 

KlausST

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Hi,

FvM is true.

With both RMS voltag and RMS current you only can calculate apparent power. For active power you need the phase shift as additional information.

Klaus
 

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