D
Daniel Rudy
- Jan 1, 1970
- 0
Hello Everyone!
I've ran into a situation where I need to sense a very large flow of
current (100A) at 24VDC or so. This is for a motor supply feed. The
problem that I'm running into is isolation because there is a
microcontroller that is part of the control circuit that electrically
needs to stay away from this line as its powered from a different
source. So far, there are two ways that I'm aware of to do this:
1. Use a very low value resistor (I would need a few in parallel),
sense and amplify the voltage across that. Then feed that into a
voltage to frequency converter so it can be sent across an opto-isolator
and then on to a timer on the microcontroller.
2. Wind a couple of turns of the main feed wire onto a torridal core
form. The torrid has a gap cut into it. Inside that gap is a hall
effect device that is epoxied into place. This inherently provides the
galvanic isolation that is required. After signal conditioning, the
analog voltage can be sent directly to a ADC input on the controller.
I would prefer to use #2 as that would be easier to implement, and it
seems to have a lower parts count. Accuracy in the area of 1 amp
resolution or better, if possible, would be good. Any advise, links,
etc. is appreciated. Thanks.
I've ran into a situation where I need to sense a very large flow of
current (100A) at 24VDC or so. This is for a motor supply feed. The
problem that I'm running into is isolation because there is a
microcontroller that is part of the control circuit that electrically
needs to stay away from this line as its powered from a different
source. So far, there are two ways that I'm aware of to do this:
1. Use a very low value resistor (I would need a few in parallel),
sense and amplify the voltage across that. Then feed that into a
voltage to frequency converter so it can be sent across an opto-isolator
and then on to a timer on the microcontroller.
2. Wind a couple of turns of the main feed wire onto a torridal core
form. The torrid has a gap cut into it. Inside that gap is a hall
effect device that is epoxied into place. This inherently provides the
galvanic isolation that is required. After signal conditioning, the
analog voltage can be sent directly to a ADC input on the controller.
I would prefer to use #2 as that would be easier to implement, and it
seems to have a lower parts count. Accuracy in the area of 1 amp
resolution or better, if possible, would be good. Any advise, links,
etc. is appreciated. Thanks.