How to prevent increasing current above a certain level?

[JBA]

One question that has not been asked is "what are you planning to use to drive your generator?"

This is critical for determining the method to control its rpm.

 

[meBigGuy]

It's kind of discouraging to go through this much discussion and still not have answers to the basic questions. There seems to be a comprehension problem.
I ask:

1. How do you control the RPM of the generator? Can we use that to control the current?

And the answer is:

ANSWER: that is element #1 above . i want to cut the current at X Amps, if drops below X Amps then should automatically allow current to flow .

Which has nothing to do with controlling the RPM of the generator. You said you can control the RPM of the generator. Please describe HOW!

 

[jim hardy]

4. Regarding your switch, it has been noted before that this has an issue. If you sense 10A and turn off, the current drops to 0 amps, and it turns back on, draws 10A and turns back off, on and off forever. How do you plan to stop that from happening?
ANSWER: I want it to go on off forever , it need to be a switch that can handle that kind of operation

"on and off forever ? "
Isn't that a PWM series regulator ? Interesting approach.

We learn more by by doing than by reading about doing. ( anyone old enough to remember Fanny Hill?)

It seems to me Benofer's idea is not clearly thought all the way through.
He needs to build something and figure out why it didn't work, climb up the learning curve as he gets it working piece by piece.

old jim

 

[benofer90]

One question that has not been asked is "what are you planning to use to drive your generator?"

This is critical for determining the method to control its rpm.

why ?

put aside the generator or anything . just looking for a method to cut current at x amps and allow current flow below (automatically) .

for the rest i will use buck convertor as suggested .

 

[benofer90]

It's kind of discouraging to go through this much discussion and still not have answers to the basic questions. There seems to be a comprehension problem.
I ask:

And the answer is:
Which has nothing to do with controlling the RPM of the generator. You said you can control the RPM of the generator. Please describe HOW!

put aside the generator or anything . just looking for a method to cut current at x amps and allow current flow below (automatically) .

for the rest i will use buck convertor as suggested .

 

[benofer90]

"on and off forever ? "
Isn't that a PWM series regulator ? Interesting approach.

We learn more by by doing than by reading about doing. ( anyone old enough to remember Fanny Hill?)

It seems to me Benofer's idea is not clearly thought all the way through.
He needs to build something and figure out why it didn't work, climb up the learning curve as he gets it working piece by piece.

old jim

Hi Jim , i can have a range as specified before but was deviating from it . it can be a range . for example : detect either overcurrent of 10 Amps and undercurrent of 5Amps so at 10 it will cut flow and below 5 it will allow current .

 

[meBigGuy]

That makes no sense at all. If you open the circuit at 10 amps, you then instantly have zero amps. Where will the 5 amps come from.

What are you getting from the buck converter? Why are you using it? What do you expect it to accomplish? We had something in mind when we suggested a buck, but I think you missed the point entirely. Do you understand what a buck converter does?

 

[JBA]

The best answers to problems are obtained when all elements of the problem are known. When you limit your input to how do I do this single element in your design, you limit the ability of the respondents. For my part, in order for me to spend time on the subject I would prefer to know whether or not the whole system is logical; or, is not simply reinventing the wheel. For example, if you were to state "I want to build my own electric welding machine" then I would suspect that there is a lot more information you require than simply how to "limit the current to 10 amps".

 

[JBA]

The reason I am asking about your driving method is that varying circuit loads result in varying loads on the generator driver; so, if you want to have any type of a stable generating system you will require a feedback system that respond to those load variations and maintain a stable rpm rate to the generator. Every type of electrical power generator has a governing system to achieve this goal; otherwise, you can end up with an uncontrolled power oscillation in your system.

 

[benofer90]

The reason I am asking about your driving method is that varying circuit loads result in varying loads on the generator driver; so, if you want to have any type of a stable generating system you will require a feedback system that respond to those load variations and maintain a stable rpm rate to the generator. Every type of electrical power generator has a governing system to achieve this goal; otherwise, you can end up with an uncontrolled power oscillation in your system.

Hi JBA,

"you can end up with an uncontrolled power oscillation in your system." which i am ok with having power oscillation in the system.
all i want is a self powered adjustable DC device to detect both overcurrent of X Amps and undercurrent of Y Amps so at X it will cut flow and below Y it will allow current . where X>>Y. where the Voltage can be from 0-30 (I'm flexible on the voltage upper limit )

thanks

 

[benofer90]

That makes no sense at all. If you open the circuit at 10 amps, you then instantly have zero amps. Where will the 5 amps come from.

What are you getting from the buck converter? Why are you using it? What do you expect it to accomplish? We had something in mind when we suggested a buck, but I think you missed the point entirely. Do you understand what a buck converter does?

Buck convertor is for another circuit which will be part of the entire system . that is why i divided my answers.

as i answered to jim and JBA above:

"Hi Jim , i can have a range as specified before but was deviating from it . it can be a range . for example : detect either overcurrent of 10 Amps and undercurrent of 5Amps so at 10 it will cut flow and below 5 it will allow current ."

"all i want is a self powered adjustable DC device to detect both overcurrent of X Amps and undercurrent of Y Amps so at X it will cut flow and below Y it will allow current . where X>>Y. where the Voltage can be from 0-30 (I'm flexible on the voltage upper limit )"

 

[jim hardy]

"Hi Jim , i can have a range as specified before but was deviating from it . it can be a range . for example : detect either overcurrent of 10 Amps and undercurrent of 5Amps so at 10 it will cut flow and below 5 it will allow current ."

look up "foldback current limiter circuit"

 

[axemaster]

I'd like to jump in an quickly mention 2 things:

1. Relays have a finite lifetime. If you have one toggling on and off constantly, it will wear out. If it's switching a large current, it may burn out very quickly.

2. I strongly recommend that whatever you do, you test it out on a low power circuit first. This is doubly true given your inexperience. As I said before, your system has 100's of watts available, and that means it has explosive potential.

 

[meBigGuy]

Hi Jim , i can have a range as specified before but was deviating from it . it can be a range . for example : detect either overcurrent of 10 Amps and undercurrent of 5Amps so at 10 it will cut flow and below 5 it will allow current ."

Can't you see the problem with that statement? How can it conduct 5 amps if it is shut off? Once you cut flow there is no current to detect.

You need to make a functional drawing of what you would like to implement. Show the source of generator RPM, how it can be controlled, how the buck is connected, what its output voltage is, where you want to sense current, and where you want to switch it off, and where the load is, and its nature. Without such a top level drawing we will keep going in circles as we have been doing.

It doesn't have to be a real schematic. Just a symbolic drawing that describes the system architecture. I think when you try to draw it you will begin to see the issues that have been raised.