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Topic: Measure High current (Read 423 times) previous topic - next topic

AMPS-N

Dear all,

I am trying to build application to measure current 15A-20A @1000v. I have build circuit with hall sensor and interface with arduino UNO using mux circuit.

Now i am trying to build circuit on shunt basis .if anyone here can put suggestion to take care during building circuit will be appreciable.
AMPS

jackrae

#1
Jun 21, 2014, 08:38 am Last Edit: Jun 22, 2014, 09:58 am by jackrae Reason: 1
There are extreme dangers associated with what you intend since your measurement circuit is always attached electrically to the 1000v supply and the only advice I could give is AVOID doing so.  It matters little whether your supply is AC or DC, the potential is equally as dangerous.

Assuming one side of your 1000v supply is "grounded", the shunt should be on the grounded side of the supply to minimise the potential that your measurement system could rise to.  But if the supply polarity should be accidentally reversed, even momentarily then your measuring device voltage becomes lethal.   Similarly if the ground connection of your supply should become open circuit due to a wiring or operating fault, the measurement connection potential could rise to a lethal value.

If your 1000v supply is "floating' ie not connected to ground, (a common practice on DC systems) then both positive and negative terminals should run at about 500v with reference to ground, so again lethal.  If a ground fault develops the measuring side could be at either 0V or 1000v, it all depends on which pole develops the ground fault.

If you are already happy using hall sensors then stick with them.  There are no prizes for winning the Darwinian medal of natural selection.  ( The process whereby those who endeavour to kill themselves by doing idiotic things manage to do so before they get a chance to breed the next generation of like minded individuals)

MarkT

#2
Jun 21, 2014, 11:01 am Last Edit: Jun 21, 2014, 11:03 am by MarkT Reason: 1
High voltage and shunt sensing do not go together.  Isolated hall sensor or a
current-transformer (CT) is needed, but CT's only work for AC.

The only way to do high tension shunt sensing is to have an entire isolated circuit
floating with the shunt (incluing its own isolated power supply) which then transmits the
value via optic fibre, opto isolator or wirelessly.

[ BTW high current at 1000V will kill, no second chances. ]
[ I won't respond to messages, use the forum please ]

AMPS-N

Is it possible to measure current using shunt resistor . Like used in clamp meter .

Its equivalent of string monitor in solar.
AMPS

Paul__B


Is it possible to measure current using shunt resistor . Like used in clamp meter .


Well, clearly a clamp meter is not a current shunt.

You originally specified you were using a Hall sensor.  That is the correct way to do it (and is precisely how a DC clamp meter works in any case), there is no need to do it any other way.


Pelleplutt

Do you have to measure at the high end (1000 volts)
Is it possible to measure at low end (0 volt)

I think it's same current going around the circuit.

Pelle

Docedison

#6
Jun 21, 2014, 09:57 pm Last Edit: Jun 21, 2014, 10:04 pm by Docedison Reason: 1
Measuring the drop across a series resistor in the ground leg of a power supply is perfectly do-able but not really advisable unless you have a means of sensing the voltage at the high side of the sense resistor to detect an open condition or all the electronics are TOTALLY isolated from everything AND I DO MEAN EVERYTHING else connected to that node....
IMO a lot of extra crap to emulate the inherent isolation provided by a hall effect device.... Safety is NEVER, NEVER a place to try to save a dollar or "Simplify" a design.
You have been advised of how to do the task 'correctly' the obvious way, Twice...
What is the underlying issue that keeps you asking about how to do something inherently VERY Dangerous.
Were your engineering skills at the same level as your 'apparent' coding skills you would know this and not ask a useless question.
1A @ 1KV is 1 KW... this is a NON TRIVIAL current and voltage and 'accidents or parts/construction failures are generally LETHAL to both the equipment and the operator.
The answer to your question about ground sensing of DC current is perfectly valid... However after 40+ years of engineering experience, Something I would NOT attempt to do... simply because the safety devices added to limit the available fault voltage are subject to failure from the conditions imposed by the measurement techniques... OR.. Are of a nature as to degrade the available accuracy... NOT under ANY circumstances a 'wise' choice

Doc
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

LarryD

Quote
I am trying to build application to measure current 15A-20A @1000v.

You will kill yourself or someone else.
Leave this to the experts!
The way you have it in your schematic isn't the same as how you have it wired up!

TomGeorge

Hi, can you tell us what the project is going to be used on please.
There may be an easier way to do it, and I'm worried that 20A x 1000V = 20kW!

Tom...... :)
Everything runs on smoke, let the smoke out, it stops running......VK3DMK

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