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Thread: Installed a VFD and the motor is running @ low RPMs???

  1. #1
    Join Date
    Feb 2014
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    Installed a VFD and the motor is running @ low RPMs???

    Hoping that someone with greater experience / electrical knowledge might be able to offer some advice. I hooked up a TECO Westinghouse L510-203 frequency inverter to a 3hp 3 phase motor this evening (dust collector blower). The VFD flashed "5.00" before I ran through the modes to set up and or check factory settings, then "run". The impeller spun in the correct direction but at a small fraction of the 3450 RPM I was expecting. I couldn't guess the speed but it wouldn't move dust.
    Here are a few of the setup parameters I've confirmed:

    • 00-05=1 for keypad controls for potentiometer (tried turning knob)
    • 02-03= 3450 RPM for motor rated speed
    • 02-04= 230 motor rated voltage
    • 02-06= 60Hz motor rated frequency


    I hooked the VFD up to a second 3ph 3phase motor and had the same issue.

    Something I haven't mentioned is that i checked both motors to see if they were wired for high voltage (460v), and I'm not sure what to make of what I saw. The first motor box was a bunch of wires & nuts without a board or diagram so I moved over the second motor. It had a nice diagram on the inside cover illustrating the high and low wiring configurations with three rows and two numbers in each row.. but the actual board was two rows of 4 connections so the diagram wasn't of help. I can say the second motor is a "Wye" configuration with 3 pairs and the 4th has 3 wires (9 total).

    Sorry for the long post but I wanted to cover what I've checked so far. Any help would be appreciated.

  2. #2
    Join Date
    Sep 2016
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    What frequency does the display claim it is running? How long does it take to get up to speed? Is it possible it is slowly accelerating over a minute or more and you turned it off too soon? Are you sure it is 240 volts in and not 120. Is it rated for single phase input. I assume you only have single phase power in the shop.
    Does the reverse function work.
    Bill D

  3. #3
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    Hi Bill,
    Thanks for your reply.
    The startup frequency is the "5.0" but you asked what frequency does the display show while it is running...which I did not know. I turned it on, hit the "enter" button when it was showing the 5.0 starting frequency; toggled over a few digits and changed the number to 60 and sure enough the motor started to make all the right sounds as it came to speed.
    Not yet sure where I failed in my setup programing? I had the accelerator timing set to 4 or 5 seconds, the max frequency at 60, and control panel potentiometer was programed. But anyway, I'm thrilled the motor works and I'm a little closer to the finish line on this project. Thanks again.

  4. #4
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    Glad to hear you've got it running!
    David

  5. #5
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    Glad it works now. It is often the simple things that are hard to figure out because they are too obvious.
    Make sure the motor is allowed to coast to a stop. No need for dynamic braking on a fan and it will save a lot of wear and tear. Often when you set the acceleration time it will automatically set deceleration to the same time.
    Bill D

  6. #6
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    Quote Originally Posted by Bill Dufour View Post
    Glad it works now. It is often the simple things that are hard to figure out because they are too obvious.
    Make sure the motor is allowed to coast to a stop. No need for dynamic braking on a fan and it will save a lot of wear and tear. Often when you set the acceleration time it will automatically set deceleration to the same time.
    Bill D
    Bill, that's so true. Glad I came here to get someone else's perspective; was ready to pull the motor apart/spend hrs of youtube videos on motor repairs.

    For archive purposes, let me mention to future hobbyists that they should check their VHD manufacturer for programming updates if their new VHD isn't operating correctly. I bought two of these TECO 51-03 at the same time and last night I opened the second box to get started on an old 3 phase cabinet saw I've had sitting around (pandemic project #9). There was an insert inside that stated the programming codes had been swapped around, meaning button controls vs knob control for the frequency. That's why the knob wasn't working on VHD #1 for the dust collector. Problem solved.

    Bill, if you happen to read this response again what is your take on safe wind down speeds for the cabinet saw? You mentioned a hard brake could stress the DC motor. Would a setting of 2-3 seconds on the cabinet saw be a good mix between personal safety and mechanical?

  7. #7
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    Quote Originally Posted by Patrick Curry View Post
    Bill, that's so true. Glad I came here to get someone else's perspective; was ready to pull the motor apart/spend hrs of youtube videos on motor repairs.

    For archive purposes, let me mention to future hobbyists that they should check their VHD manufacturer for programming updates if their new VHD isn't operating correctly. I bought two of these TECO 51-03 at the same time and last night I opened the second box to get started on an old 3 phase cabinet saw I've had sitting around (pandemic project #9). There was an insert inside that stated the programming codes had been swapped around, meaning button controls vs knob control for the frequency. That's why the knob wasn't working on VHD #1 for the dust collector. Problem solved.

    Bill, if you happen to read this response again what is your take on safe wind down speeds for the cabinet saw? You mentioned a hard brake could stress the DC motor. Would a setting of 2-3 seconds on the cabinet saw be a good mix between personal safety and mechanical?

    I have heard that less then 3 seconds is hard on the drive line. There is not much flywheel effect on a tablesaw compared to a grinder or a lathe which should take longer to stop safely. For a ten inch saw I think 3 seconds is fine. If you stop too fast it is possible for the blade nut to unscrew, in theory.
    If you have too much rotating mass and stop too fast and too often you can damage the VFD.
    Bill D

  8. #8
    Join Date
    Aug 2017
    Location
    Arlington, TX
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    If the cabinet saw takes standard blades with no holes for anti-rotation pins, the arbor nut will loosen if the arbor is slowed too quickly, and the nut and blade could come off the saw.

    When I was in shop class in the late 1970's, they had just gotten a new RAS with an electronic brake, set at the factory. The first time they had turned it on (no students present), when they turned it off, that saw blade came off, flying across the shop floor, into the wall on the other side! Thank goodness the two instructors were not hurt. The factory sent a rep out to adjust the brake properly.

    In a cabinet saw, the blade might not escape the cabinet, but it won't do itself or the cabinet any good for certain!

    -- Andy

  9. #9
    I also have a TECO L510 Drive and I believe it is set at 5 hertz at the factory. Iím almost positive mine was the same way. I had to up the hertz to 60 too.

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