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  1. SCOC

    bipolar tvs

    I have 2 comments about this 1. Using two packcages in series, compared to 1 bi-directional package, may result in a bit more lead inductance so your peak voltage during ESD discharge may be a bit higher. Ultimitely, your test will confirm the pass/fail result. 2. Generally, ESD is a CE...
  2. SCOC

    60079-11 Ferrite Bead Inductance Calculation

    I have a design which needs to meet IEC 60079-11 instrinsic safety. Does anyone have experience calculating the inductance of ferrite beads specifically for IS? I have been told that the inductance needs to be calculated at 1KHz for IS, however, the datasheet for the ferrite bead we are using...
  3. SCOC

    Conformal Coating on IDC Ribbon Cable Connector?

    Thanks for the replies. This connector is direct wire to board, impossible to disconnect/reconnect after coating. Product uses forced air cooling which contains dust and other contaminents, so we are trying to keep as much as possible out from corroding the contacts. We've experienced no...
  4. SCOC

    Conformal Coating on IDC Ribbon Cable Connector?

    I am using an IDC type ribbon cable connector (TE 2-746610-4)in a fairly dusty/dirty environment. We have been conformal coating the connector, including top holes, on the assembly after the cable is crimped in of course. Our manufacturer is now saying that it could be an issue if the coating...
  5. SCOC

    VFD Overvoltage Trip - what exactly happens?

    Thanks for the replies. So in the case of an AC line surge, the only real protection for the IGBTs a drive has is its DC link inductor/caps acting as a low pass filter, and external protection like SPDs and line reactors. Of course there may be MOVs internal to the drive too. And as Mark...
  6. SCOC

    VFD Overvoltage Trip - what exactly happens?

    Greetings, I am wondering what exactly happens in an IGBT driven VFD drive when it trips due to overvoltage. I presume that in all cases there is voltage detection on the DC bus. Once it goes above a certain threshold, the drive "trips". What exactly does the drive do to protect from the...
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