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    #16
    Originally posted by Jraef View Post
    that's where the line reactors help. They slow down the rise time of the surges and if the drive is running
    They slow down di/dt. For spikes, the concern is dv.

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      #17
      Originally posted by Besoeker3 View Post
      They slow down di/dt. For spikes, the concern is dv.
      Yes, the current through a series inductor is the integral of the voltage across it (plus a constant) and so it will slow down the rate of rise (and the rate of fall) of the current. Of course if you wanted the highest protection level you would add a surge protector in front of a line reactor to clamp any large voltage spikes before the inductor can store much energy from a voltage spike.
      It would be interesting to know what the stray capacitance is across a typical reactor inductance due to the interwinding capacitance. That would limit how much it could slow down fast rising voltage spikes

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        #18
        Originally posted by Besoeker3 View Post
        They slow down di/dt. For spikes, the concern is dv.
        His concern is "tripping out", which unless he returns and discloses the meaning of that, means it is all speculation at this point. But as a general rule, I recommend line reactors on almost all VFD applications, they are cheap insurance.
        __________________________________________________ ____________________________
        Many people are shocked when they discover I am not a good electrician...

        I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

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          #19
          Originally posted by Jraef View Post
          Yes, line reactors. What a line reactor does mainly for a VFD is to slow down the rise time of any transients on the incoming line side, so that they don't cause the dc bus to spike up and either trip the drive, or damage the capacitors and diode bridge. I call them "cheap insurance" fro expensive drives.
          They also limit fault current.

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