Shunt Resistors For AC Current Measurement

One thing you have to take in care that Isolation is not possible this would be very useful for fresh usages which you go to design or develop infuture

The lack of isolation can easily create unexpected complications that cause circuitry to fry. To provide proper isolation one can quickly lose all implied accuracy of using a shunt resistor instead of a current transformer. You can also have bandwidth complications that your CT were limiting that a resistance won't.

If I were you I'd use one of the Yokogawa CT calibrated to be used with this power meter. This way everything stays calibrated.

Hi Vishram,

Very good comments here and you have done some good homework. I would add the following to think about.

1. Do a three point current plot. Run and measure your motor under load at 10% and 50% of full load to make sure your shunt is linear. Some people use a precision analog HP AC voltmeter for reiteration. This will also check for current harmonics the Yoko may not see.

2. Some new AC Motor Drives can reach 0.1% accuracy at 10% of full scale internally with no external components and provide you with a usable output to monitor each phase for current balance.

3. Temperature may be a factor depending on the shunt design you select.

Isolated Hall probe shut ICs are available from Avago / Winson/ Siliconlabs - pl see Google and search. I do not see any difficulty in using these as long as the sensor is rigidly mounted with respect to the current cable- relative positions are imporatnt as it is measuring flux density due to the main current.

I'm not sure I fully comprehend the details of what you are trying to accomplish. However, I have had related problems and for 10 years have been using Rogowski coils and electronic integrators with almost utter reliability. This method has been superior to shunts and Hall effect devices for our high current welding applications.

Here is a link to some useful information on the various methods of current measurement and the features of each.

http://fwbell.com/downloads/files/Methods_Current_Measurement.pdf

If your goal is to electrocute someone, then go ahead and uses resistors.