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Using PIC microcontroller to measure high voltage andcurrent

Discussion in 'Microcontrollers' started by GraveYard_Killer, Aug 8, 2004.

  1. Wond3rboy

    Wond3rboy Member

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    Hi the EPE mag isssue is Feb 2005. But i found something better(dont know its authenticity) its supposed to have all projects published in EPE since 1995.

    EPE PIC Mirror

    This ones from 1995

    PIC Electric Meter

    This is from 2005

    PIC Electric MK2
     
    Last edited: Jul 1, 2009
  2. unknown118

    unknown118 New Member

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    can i use a ordinary resistor instead of a shunt resistor in measuring current?? there's no available shunt resistor at our place so instead of using shunt any other way or do you know other circuit regarding my problem?

    hope u guys can reply to my problems tnx alot :)
     
  3. spindrah

    spindrah New Member

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    Sure, just make sure you don't go over its rated wattage
     
  4. dave

    Dave New Member

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  5. Oznog

    Oznog Active Member

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    Well, a shunt resistor typically MEANS it's a low ohms resistor, also usually means high precision and high power rating. So NO, you cannot replace it with a non-shunt resistor unless you put a lot of them in parallel.

    A "normal" 100ohm resistor with 1 amp pushed through it drops 100V and 100W. Nowhere near usable.
     
  6. spindrah

    spindrah New Member

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    like I said, there is nothing wrong with using a resistor as long as you don't go over its rated wattage.

    what is the point of using a 1000amp shunt if you are dealing with 30mA?
     
  7. Sceadwian

    Sceadwian Banned

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    If it's 30ma you don't need a 'shunt' Many electronics devices I've pulled apart have 1ohm or 10ohm resistors used as shunts, as the current is so low modest power loss isn't an issue as long as it's a plug in device. High precision is generally speaking not an issue as it'll have to be calibrated regardless. That being said lower values of resistance mean lower power dissipation in it which means better stability. You could if you wanted and had a decent low noise opamp simply tap any two slightly different points of the power leading into a circuit and use that has a shunt, the current is already going through that trace, if you calibrate it there's no reason to use anything special.
     
  8. Muhammad Hassan Akhtar

    Muhammad Hassan Akhtar New Member

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    I need to measure 220 V and currents around 13 Amperes using PIC micro-controller. The circuit I have designed on Proteus using differential amplifier that converts 220 Volts to 2.5 volts (0-5 volts range) taking 40 samples of the peak voltage is given below. The ADC of PIC is used for converting analog voltages into digital. The voltage divider divides the voltages into half so that it comes in the range of (0-5 volts) which can be read by PIC. It's showing the values of voltage and current on the input side accurately on LCD but I have some confusions regarding this circuit.
    1. First of all is this circuit okay as I have some doubts about it?
    2. Should I use a current transformer and voltage transformer on the input side?
    3. The 1 ohm bypass resistor should be used if I use a current transformer or should I use only high power wire wound resistor only instead of CT for current measurement?
    (I'm a student so I don't have much experience in this area. So kindly explain everything)
     

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