Circuit for dc voltage & current sensing

[parihar1988]

Dear all
i have urgently required a circuit which can sense dc voltage up to 1000v and dc current upto 30amp.
Please help me as soon as possible.


Amit singh

 

[jiripolivka]

There are many such circuits available. To "sense" means to translate the high DC voltage to a lower level that can be processed easier. The straightforward way is to use a resistor divider, say 100 MOhms as the load, with a "tap" on it close to ground. What is your "sense" input?

With DC current the situation is similar, use a shunt resistor, say 0.1 Ohm, then across it you get 3V to process. Certain problem may be the voltage to ground on the current loop but there are opamps designed for this purpose.

Knowing Ohm's Law is enough, plus some knowledge of DC circuits.

 

[D.A.(Tony)Stewart]

Dear all
i have urgently required a circuit which can sense dc voltage up to 1000v and dc current upto 30amp.
Please help me as soon as possible.


Amit singh

1kV is lower than what is expected on 120Vac lines. Are you sure 1kV is the limit for detection & isolation? There are many ways to use resistor ladders to ensure adequate breakdown voltage. Current is easy to detect and best when shunt does not generate self-heating and user must know the thermal resistance of shunt to determine maximum power level. e.g. if rated for 5W then use 1W @30A or ~ 1mV/30A shunt or 33mΩ 5W shunt thus gain required depends on ADC range and resolution required determines Vio offset error over temperature. Then you must define time resolution for measurement and if any peak and hold measurement is also needed. Output requires very low noise and input offset, so auto-calibration method may be needed and noise filtering from EMI.

Once you have defined your requirements better, a solution can be determined.

 

[schmitt trigger]

I always avoid answering a newbie post with the phrase: "This are dangerous voltages and currents, do you know what you are doing?"

As the previous poster mentioned, these is a fairly straightforward application of Ohm's law. But the current/voltage levels require a good understanding of the hazards involved, and the auxiliary components required to achieve the task safely.

Therefore -unfortunately- this time I've to ask, do you know what you are doing? Do you understand the hazards? How are you going to protect against faults?

 

[mike.zhang]

How about ACS712 ? It's a current sensor with 2.1kVrms voltage isolation.