Analog multimeter vs Digital multimeter

This topic contains 5 replies, has 2 voices, and was last updated by John C John C 8 months, 3 weeks ago.

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  • #8171

    Gus Tokenheimer
    Participant

    What is the advantage of using an analog multimeter compared to using a digital multimeter. What can I use an analog multimeter to measure that digital DVM aren’t good at doing. I know the analog meters have higher test currents compared to DVM meters. Any circuits designs under test that analog multimeters are used for when testing or troubleshooting boards?


  • #8172
    John C
    John C
    Galco Representative

    Hey Gus thanks for asking Galco. Digital meters are hard to beat for accuracy, especially on Ac or DC voltages. However the good old analog meter will show a voltage moving around easier to see than watching a display count up and down. Also the old analog meters will filter noise differently to represent a signal. This may not make much sense until you are trying to measure motor voltage driven by a VFD. There are true RMS digital meters that get close, but that usually depends on the carrier frequency the drive is set for, eh? I’m of the opinion that there is still a place for both.


  • #8173

    Gus Tokenheimer
    Participant

    So you use an analog meter to measure the variable frequency drives controllers AC output voltage? I’m guessing analog meters can measure a high AC frequency voltage compared to a digital meter?


  • #8174
    John C
    John C
    Galco Representative

    Well not exactly, it is because it doesn’t measure high frequency that you can see the motor voltage. However keep in mind 2 things with AC motor voltage from a VFD, 1) very difficult to see it below say 10Hz, because the needle will just jump up and down anyway, and 2) the accuracy of the Simpson 260 measuring may not match what the drive says it is doing on the drive’s display because of the math the drive uses to precisely calculate the actual output voltage, ok?


  • #8175

    Gus Tokenheimer
    Participant

    So how are you using the Simpson 260 or analog meter to measure the VFD. What are you using the Simpson 260 or analog meter to measure what on the VFD controller circuit or AC motor?


  • #8176
    John C
    John C
    Galco Representative

    I was kind of hoping you would ask that. Ok so you may not have the most accurate reading, but you still have a reference point. Make sure all 3 phases match with in 10%, T1 to T2, T1 to T3 and T2 to T3 ok, and if you have another drive you can run at the same speed, then measure that drive output and compare, again you should match within 10% (if using same V/F patterns).


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