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VFD over-voltage error (E 07)

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  • VFD over-voltage error (E 07)

    Everything wired and fired up nicely but for an E 07 error when the motor is turned off at higher speeds.
    No problem with the mechanical variable speed head cranked down. ("When the DC bus voltage exceeds a threshold due to regenerative energy from the motor")

    I understand the motor may be generating power on shut down and I can't remember what setting I have for internal
    VFD braking but, does this sound like a candidate for an external braking resistor?

    Never had this problem with this VFD on the gear head mill but plenty of friction to slow things down there.

    Hitachi SJ200.

    Apparently the internal resistor has braking torque of 20%
    Last edited by QSIMDO; 09-08-2018, 07:26 PM.
    Len

  • #2
    Lengthen the ramp down time. Try 5 seconds, and work from there.

    Comment


    • #3
      One reason I usually use the "coast to stop" feature on my VFDs.
      CPeter
      Grantham, New Hampshire

      Comment


      • #4
        Coast-to-stop eats the day away and makes flipping from fwd to rev useless. I use braking resistors on all my VFD to great effect. Never have used the mechanical brake.

        So.. use an external braking resistor... AND (most important) invoke the parameter that extends deceleration if voltage rises. That will take care of varying tool weights and speeds. Set B130 to on. Turn that on now even without a braking resistor.

        On the SJ200-022 a 300W 120v element of some type works wonders. I use an engine block heater.
        Last edited by lakeside53; 09-09-2018, 12:54 AM.

        Comment


        • #5
          a typical 2 hp motor probably consumes 2-300 watts under full v/hz excition regardless of how fast the motor is spinning.

          so when the ramp down time is less than some value, the motor will back drive the vfd enough to supply the motor losses and the 30 or so watts the vfd consumes. if the ramp down time is optimal, then the motor will just barely charge up the vfd capacitors as it slows down. this could still be pretty quick. 300 watts or so of electrical power pulled from a 2 hp induction motor is probably equivalent to 400 watts at the shaft.

          but if the ramp down time is too slow then the vfd will be powering some portion of the motor's no load losses and this is not optimal.


          coast to stop will not extract any power from the induction motor because electrically its dead, and this of course can take a very long time.
          Last edited by johansen; 09-09-2018, 01:03 AM.

          Comment


          • #6
            Originally posted by johansen View Post
            a typical 2 hp motor probably consumes 2-300 watts under full v/hz excition regardless of how fast the motor is spinning.

            so when the ramp down time is less than some value, the motor will back drive the vfd enough to supply the motor losses and the 30 or so watts the vfd consumes. if the ramp down time is optimal, then the motor will just barely charge up the vfd capacitors as it slows down. this could still be pretty quick. 300 watts or so of electrical power pulled from a 2 hp induction motor is probably equivalent to 400 watts at the shaft.

            but if the ramp down time is too slow then the vfd will be powering some portion of the motor's no load losses and this is not optimal.


            coast to stop will not extract any power from the induction motor because electrically its dead, and this of course can take a very long time.
            Informative, But how does this information help?

            Change the numbers, and the math can satisfy any combination of motor drives,

            A dump resistor will help the OP, as will prolonging the decel time.

            Comment


            • #7
              Yes.. but more importantly, set B130 to on... That is the underlying mechanism with variable loads and speed to allow the VFD to give "best efforts" to stop without trip. It's "ok" on a S200 but way better on the WJ series. I can decelerate from 6000 rpm without a trip, but the deceleration time (constant tooling mass) will be extended from say 3000 rpm

              Comment


              • #8
                Yup, braking resistor. A lot of times a cheap braking resistor can be found in range top heating elements. You can also add extra capacitance to the bus of the VFD which makes it take longer before the it over-volts.

                Comment


                • #9
                  Raising the Overvoltage Threshold on mine helped. A 220/240v 3ph usually has a setting of 440/460v. I think I raised mine to 600v or more. I don't have my book in front of me--It's in the shop and all my settings are in notes.

                  But... If you're still running that extra motor off part of the phase, all bets are off.

                  Comment


                  • #10
                    Thanks guys!

                    Now, with cheaters on and magnifier in hand, I go forth to find out how to do all this in yet another, ridiculously small print operation manual!
                    Len

                    Comment


                    • #11
                      YES!!

                      PDF version!
                      Len

                      Comment


                      • #12
                        Originally posted by CCWKen View Post
                        Raising the Overvoltage Threshold on mine helped. A 220/240v 3ph usually has a setting of 440/460v. I think I raised mine to 600v or more. I don't have my book in front of me--It's in the shop and all my settings are in notes.

                        But... If you're still running that extra motor off part of the phase, all bets are off.
                        What "extra motor"?
                        I get another machine I didn't know about?
                        Len

                        Comment


                        • #13
                          Anything over 5 seconds deceleration and I get "E05" error.
                          Anything under is "E07".

                          All with B130 on.
                          Len

                          Comment


                          • #14
                            Originally posted by QSIMDO View Post
                            What "extra motor"?
                            I get another machine I didn't know about?
                            I thought you were the one trying to run a 1-phase motor at the same time as a 3-phase off the same VFD output. Something like that. I don't recall but it was just a few days/week ago.

                            Comment


                            • #15
                              Originally posted by CCWKen View Post
                              I thought you were the one trying to run a 1-phase motor at the same time as a 3-phase off the same VFD output. Something like that. I don't recall but it was just a few days/week ago.
                              Naah, the only other motor I have is a pancake fan to cool the vari-speed and that's connected before the VFD.
                              Len

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