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How to make a sensitive current sensing device?

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rolandchok

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hi guys do you any idea how to make a sensitive current sensing device? a device that can sense even a small amount of current flowing. thanks operates 3 to 6A or 220V wire. thanks
 

Current Sensing

In ICs we use to measure voltage drop across a resistor because is easier... at other scale you could do the same....
 

Re: Current Sensing

I post a picture that should work in theory. That is I know it'l work if you make it right and fine tune it.

If the current is AC, then you have to use a little transformator that does make only a minimal voltage drop.
 

Re: Current Sensing

i forgot to mention that the current to be measured is from an AC voltage source. its from the main line. thet said the only way to measure it is through a "magnetic current sensing" ferrite toroid. any idea how to make one. i found out that the maximum can be drawn from the AC outlet is 300A. but that is for max current. but in conventional house. how much current is actualy flowing in the house to power up a small house hold.
 

Current Sensing

kinda of like a transformer with magnetic coupling
to pick up the current?
 

Re: Current Sensing

Current transformers are standard parts in electric instrumentation, available from all major manufacturers. They usually have secondary current of 1 or 5 A for full scale.

Small current transformers respectively sensors for instruments (e. g. electronic meters) are also available from several manufacturers, e. g. from Talema/Nuvotem http://www.nuvotem.com/en/products/pdf/CT Catalog Jun-06.pdf

Technically, current transformers can be calculated like any transformer, following the same basic relations. Although you may use ferrit torroids, they generally use tape wound cores from high permeable magnetic alloys.
 

Re: Current Sensing

you can try use hall effect current transducer...from LEM, i just use it to complete my power factor correction unit project..all the best!!!
 

Re: Current Sensing

can you actually do you have any idea on how to make a magnetic current sensing. the computation for the winding materials to be use. just a wild idea on building one. i give up to AC motor coz i could not find a driver IC IR2110 i was try to order one. i don't know yet if its available. i could not find any in our electronics stores in here.:cry: any ways. any good idea for a project?
 

Re: Current Sensing

I think, this has been discussed in the forum many times before. I assume you have a one turn primary winding, then the number of secondary turns sets the current ratio, you can define it to your needs. Commercial sensors as shown above give an idea of possible dimensioning. The secondary winding has to be terminated with a low ohmic resistor.

The sum of load resistor and winding resistance in relation to secondary inductance defines the lower cutoff frequency fg = R/(6.28 • L). Also, the core has a maximum voltage integral per turn. Above this value (could be calculated as a maximum secondary voltage for a given operating frequency) the core gets saturated and the measurement distorted.
 

Re: Current Sensing

the materials to be use do you have and idea. copper wire? the core it self what it should be made of and where can i particularly get it? thanks.
 

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