Connect with us

AC milliameter

Discussion in 'Electronic Basics' started by Joe Lees, Apr 1, 2004.

Scroll to continue with content
  1. Joe Lees

    Joe Lees Guest

    I have recently purchased 2 AC milliameters 0 to 500milliamps, I want to
    use these meters to read ac current in the range of 0 to 30 amps, can a
    shunt resistor be used as in DC meters, I havent actually received the
    meters yet so I dont know the value of the meter movements

    Thanks Joe L
     
  2. Can't see any reason why not ??
     
  3. JeffM

    JeffM Guest

    I...purchased 2 [500milliamp] AC milliameters
    ....or a non-invasive solution: current transformers.
     
  4. Rich Grise

    Rich Grise Guest

    The internal resistance of your meter is going to be
    way low, and so calibrating a shunt will be a real PITA.
    One thing that can help is to put a resistor in series
    with the ammeter, turning it into sort of a voltmeter -
    they used to use 1mA meters and call them a "1000 ohms
    per volt" meter, a 50 uA movement gives you "20K ohms
    per volt", I think for a 500 mA meter, a 2 ohm series
    resistor would give you a "2 ohms per volt" meter. Since
    the meter movement resistance is probably practically
    negligible, just use 2 ohms then for your shunt calc.
    (and still 500 mA FS, but you'd be losing 2 volts from
    the circuit).

    To actually measure the internal resistance of a meter,
    you need two pots. Start with one in series with the
    meter and a supply, and adjust to full scale. Put the
    other pot in parallel with the meter (without changing
    R1) and adjust for exactly half-scale. The pot is now
    equal to the meter's internal resistance.

    Have Fun!
    Rich
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Similar Threads
There are no similar threads yet.
Loading...
Electronics Point Logo
Continue to site
Quote of the day

-