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  • Test motor on Bt3k

    Someone told me that I should test amperage draw on motor to ensure that windings are not burned out.

    I have a small el cheapo ( free from Harbor Freight) multimeter but I don't think it is the right thing to use.

    I found some clamp multi meters but I don't know if that is the way to go.

    I wonder if my source of info is blowing smoke rings or something.

    if anyone has comments or info I would appreciate it.

    thanks,

    Lee

  • #2
    Problem with checking amperage on an appliance, motor, tool, etc., is that you have to interfere with the current passing from the supply to the tool In other words, the current has to pass through the meter as it goes to the object that is being powered, so that you can measure the "current flow".

    Easiest tool that I've found for measuring amperage, watts, etc. is the "Kill-A-Watt" energy meter which you simply plug into the outlet and then plug the tool into it. There's a series of selection buttons on the Kill-A-Watt meter that allows you to select Volts, Amps, Watts, Hz, or KW hours used during the duration of operating time. Real simple to use, and it is currently available at Harbor Freight or other sources for about $25.

    https://www.harborfreight.com/kill-a...tor-93519.html

    I bought mine at Lee-Valley several years ago and have used it to measure several tools and appliances over the years.

    Hope this helps,

    CWS
    Think it Through Before You Do!

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    • #3
      CWS,

      Thanks for the info. I had somehow thought of that as I have a Kill-a-watt but it seemed that it would have been too simple. I will give it a try

      Lee

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      • #4
        Originally posted by cwsmith View Post
        Problem with checking amperage on an appliance, motor, tool, etc., is that you have to interfere with the current passing from the supply to the tool In other words, the current has to pass through the meter as it goes to the object that is being powered, so that you can measure the "current flow".

        Easiest tool that I've found for measuring amperage, watts, etc. is the "Kill-A-Watt" energy meter which you simply plug into the outlet and then plug the tool into it. There's a series of selection buttons on the Kill-A-Watt meter that allows you to select Volts, Amps, Watts, Hz, or KW hours used during the duration of operating time. Real simple to use, and it is currently available at Harbor Freight or other sources for about $25.
        The Kill-A-Watt is a good option, and a good tool to have for checking appliances, etc.

        Interfering with the current flow is one way to measure current, but it can also be measured inductively. That's how the clamp-on type current meters work, they clamp around the wire and measure current without interrupting flow. Even the low cost HF versions seem to work pretty well, I use them often.

        --------------------------------------------------
        Electrical Engineer by day, Woodworker by night

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        • #5
          Thanks Woodturner,

          A "clamp-on" meter is something I've never owned, so no experience with. I have several multi-meters going way back to the 70's, but never looked at a clamp-on for it's additional features. I'm never too old to learn something new, but kick-myself for not knowing this.

          Thanks,

          CWS
          Think it Through Before You Do!

          Comment


          • #6
            Thanks Woodturner and CWS,

            I will first try my kill-a-watt and then I'll go to HF and pickup a clampdown meter. I almost got one when my CRV was having battery problems due to a parasitic discharge. I got tired of using my HF multimeter with with leads held to battery and cable with vise grip pliers and took it to a Honda dealer who found a broken shorted bulb and a bad relay.

            Now I question how a broken/shorted taillight bulb would cause a battery drain when car is not running and the lights are off - it should have been an open circuit.

            Lee

            Comment


            • #7
              You’ll need to build a test cord so that you can separate the 3 wires. The clamp meter only reads the “hot” wire. If you clamp it on the cord it will read zero.
              Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison

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              • #8
                I would use the Killawatt first and I am en elecrtrical engineer with breakout power cords, clamp on ammeters and DMMs with clamp on probes and direct reading.
                The Kill-a-watt is so easy and accurate and rated to 15 Amps.
                Test the motor in place. Unloaded it won't draw (I think but 1-2 AMps) but don't hold me to that.
                I really don't think you need to test it at all.
                If it plugs in and you apply power with no smoke then its probably OK, the motor will spin at maximum RPM.which is about 4500 RPM.and a pretty good whine,
                I don't see why the ammeter would tell you anything special. Don't understand the point of doing that.
                If the windings are shorted you will blow up your meter anyway if the circuit breaker in your house doesn't trip first. Why risk your meter to see if its shorted when just plugging it in will do that?
                Loring in Katy, TX USA
                If your only tool is a hammer, you tend to treat all problems as if they were nails.
                BT3 FAQ - http://www.sawdustzone.org/forum/dis...sked-questions

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