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  1. #1
    Join Date
    Jan 2009
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    question for the guys working on VFD chillers

    I am looking input on what you guys use to check the load side of the vfd. Does your RMS meter work on the load side? I was told because of the simulated DC block wave that mimics an AC sine wave you need a special type of meter. I can buy an amp clamp the can check vfd amps but I am wondering what you guys use in the field for checking the volts?

  2. #2
    Join Date
    Feb 2017
    Location
    New York
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    For normal logging and light troubleshooting, I go off what the front panel says. I haven't seen an issues with my Fluke 87V.

    Sent from my SM-G935U using Tapatalk
    -----Stop, step back, relax and have another go at it.-----

  3. #3
    Join Date
    Nov 2011
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    East Side
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    Your line side amp draw is accurate for normal troubleshooting. Are you having an issue?

  4. #4
    Join Date
    Jan 2009
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    winnipeg
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    Thread Starter
    its not the line side I am referring to, but the load side of a VFD. I was told that a standard true RMS meter wont give you a true reading of voltage or amperage because of the choppy sine wave of converting dc to ac. I just found a meter from amp probe that claims to do load side voltage and amperage readings. Its more of a question for the guys out there who work with vfds and there findings.

  5. #5
    Join Date
    Jan 2009
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    winnipeg
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    Thread Starter
    what are the voltages you are working with? and are you checking load side of the vfd? It just meant to be a conversation piece

  6. #6
    Join Date
    Aug 2018
    Location
    Chicago + Suburbs
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    Quote Originally Posted by BennyD View Post
    For normal logging and light troubleshooting, I go off what the front panel says. I haven't seen an issues with my Fluke 87V.

    Sent from my SM-G935U using Tapatalk
    Benny are you using the clamp attachment on that meter?

    Sent from my SM-G973U using Tapatalk

  7. #7
    Join Date
    Nov 2011
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    East Side
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    I check amp draw on speed drives all the time on load side. Not specifically chillers, As I only check them when I suspect an issue, but pumps, AHU’s etc. never had any issues.

  8. #8
    Join Date
    Dec 2014
    Location
    New Mexico
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    I am with Chops small drives yes on load side. But reaching into a 1100 HP on full tilt buggie no way. Even with a full arc flash suit. The drives have enough checks and balances in side to be very precise on amps and output voltages.
    A few years back when having the exploding DC cap. problem big Daddy Karl came down with a box of Fluke meters that used small diameter flexible amp leads that we could put on everything. Input, output AC and the DC bus run the cables out and read / record nice and safe. Looked like NASA shooting a rocket.


    Sent from my iPhone using Tapatalk

  9. #9
    Join Date
    Aug 2006
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    Mixing oil and fire with a big spoon.
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    Quote Originally Posted by Chev5372 View Post
    I am with Chops small drives yes on load side. But reaching into a 1100 HP on full tilt buggie no way. Even with a full arc flash suit. The drives have enough checks and balances in side to be very precise on amps and output voltages.
    A few years back when having the exploding DC cap. problem big Daddy Karl came down with a box of Fluke meters that used small diameter flexible amp leads that we could put on everything. Input, output AC and the DC bus run the cables out and read / record nice and safe. Looked like NASA shooting a rocket.


    Sent from my iPhone using Tapatalk
    Rogowski coils.
    "Right" is not the same as "Wise".

    Don't step on my favorite part of the Constitution just to point out your favorite part.

  10. #10
    Join Date
    Dec 2014
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    New Mexico
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    One of the meters was a Fluke 435-II


    Sent from my iPad using Tapatalk

  11. #11
    Join Date
    Nov 2011
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    Yeah, safety should be the bigger point about checking drives. Having a large (or any) HP speed drive cabinet open during operation is never a good idea.

    A year or so ago, we had a chiller drive explode. Thankfully nobody was there when it did. When the door was opened, parts fell out on the floor.

    I’ve got a fluke meter with the flexible cord adaptor for checking amperage on large equipment. It’s Bluetooth capable, so I can keep the doors closed and monitor it from my phone.

  12. #12
    Join Date
    Aug 2006
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    Quote Originally Posted by Chev5372 View Post
    One of the meters was a Fluke 435-II


    Sent from my iPad using Tapatalk
    Fancy! I only have the 435. It is sweet, though.
    "Right" is not the same as "Wise".

    Don't step on my favorite part of the Constitution just to point out your favorite part.

  13. #13
    Join Date
    Dec 2014
    Location
    New Mexico
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    It was quite the box of meters and leads.


    Sent from my iPhone using Tapatalk

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