AC current measurement

[ramanc51]

i like to measure AC current range 1 to 20A.What is the easiest and cheap method to measure it?

 

[Tahmid]

For ease of use, you can use a current transformer or a hall-effect sensor. They wouldn't necessarily be cheap though.

 

[Junus2012]

what meaning of method ? and these current where it found like?

 

[Tahmid]

Do you mean that you want to measure it, as in, using a meter? If so, use an ammeter. Since it's AC, you can also use clamp ammeters.

Or do you want to measure the current using, eg a microcontroller? If so, use hall-effect sensor or current transformer as mentioned above.

 

[Junus2012]

yes if you are asking about a meter then the clamp meter is the easiest way

 

[ramanc51]

These current range to single and three phase motor control using microcontroller?. Can i use ferrite core as current transformer that available in computer SMPS that shown on picture?. if answer is yes. then how many turns used for primary and secondary winding and diameter of copper wire?View attachment 83274

 

[tpetar]

Calculator:

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SPLIT-CORE:
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Additional Info:
https://en.wikipedia.org/wiki/Current_transformer


The electrical performance of split-core current transformers is not as good as that of the continuous toroidal coil. The “circle” like (or “ring” like) shape of the toroid usually offers a shorter magnetic path length than other cores. Since the toroids are continuous, they do not add any air gap to the core structure. Split-core current transformers (including toroidal split- cores) add some air gap to the core structure.

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CT should always be shorted across the secondary terminals. The reason is very high voltages will be induced at the terminals. Think of the CT as a transformer, with a 1 turn primary and many turns on the secondary. When current is flowing through the primary, the resulting voltage induced in the secondary can be quite high, on the order of KV.

 

[ramanc51]

Now i decided to use ACS712 20A version. How to connect AC load to measure the current it takes?

 

[Tahmid]

Here is the datasheet: https://www.allegromicro.com/~/Media/Files/Datasheets/ACS712-Datasheet.ashx

You can find connection information here:
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These pictures should help make it easy to understand for you:

Hope this helps.
Tahmid.

 

[tpetar]

Several examples with ACS712 and PIC source codes :

A brief overview of Allegro ACS712 current sensor (Part 2)
https://embedded-lab.com/blog/?p=4529

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A brief overview of Allegro ACS712 current sensor (Part 1)
https://embedded-lab.com/blog/?p=4469

3 digits Digital Ammeter (AC / DC)

https://coolcircuit.com/project/digital_amp_meter/picmicro_digital_amp_meter.html

 

[ramanc51]

I have asked how to connect AC load through ACS712 to measure load current?

 

[tpetar]

From link in post #10 - Part II :

"Keep in mind that the ACS712 sensor provides an instantaneous output corresponding to the current flowing through the conduction terminals. If the current flow is in positive direction (from pins 1 and 2 to pins 3 and 4), the sensitivity of the device is positive, and the ACS712 output voltage rises above Vcc/2. But if the current changes its direction, the sensitivity will be negative and the output of the ACS712 decreases below Vcc/2. This means, for an AC current, the 10-bit ADC output measured by the microcontroller oscillates about 512 counts. Therefore, the microcontroller needs to sample the sensor output fast enough so that the RMS value of the current can be computed from them."


Method of connection to AC is the same. Sensor can meter AC/DC but calc in uC will be different.

 

[Tahmid]

I have shown that quite clearly in post #9. https://www.edaboard.com/threads/272292/#post1167595