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  • Users: JSong
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  1. JSong

    Grounding rod spacing

    Thanks a lot for sharing your experience and spreadsheet! It makes sense to go through the IEEE 80 process. Are there any empirical guidelines without doing those iterative calculation? In industrial facility ground design, quick and somewhat over-killed ground designs were seen in those...
  2. JSong

    Grounding rod spacing

    Hi, If designing grounding for a new fabrication facility that is 500’W x 1000’L and that it is intended to have a perimeter ground grid, plus we plan on installing 10’L ground rods periodically, what's the appropriate spacing for those rods? NEC 250.53 (B) requires a minimum of 6-ft between...
  3. JSong

    Motor Circuit Surge Surpression

    Sorry Bill, I miss-typed on the rating. It is 1/2HP rated. Here are information about the original limit switch (MICROSWITCH BZ-2R-A2) and the replaced limit switch later on (MICROSWITCH BM-1R-A2) within the temperature switches. The original one is 1/8HP rated at 125VAC and is not sufficient...
  4. JSong

    Motor Circuit Surge Surpression

    Yes, it is an 1/6HP AC motor.
  5. JSong

    Motor Circuit Surge Surpression

    Thanks for your inputs! The environment is all right and we don't think that is the key reason causing this problem. We have a few of units with the same setups in different locations, and this failure happens in several of them. It has to be due to the circuit. Diode type surge suppression is...
  6. JSong

    Motor Circuit Surge Surpression

    Dear all, We have a temperature limit switch that controls a 1/6 HP single phase motor/fun. This limit switch is 1/2HP rated according to the product sheet, however, it failed (welded and shut) due to arcs across the contacts caused by inductive kicks. I am wondering if there is a practical...
  7. JSong

    Temperature Limit Switch Failure

    Thank you all for the inputs. It is a limit switch that is triggered by a temperature sensor/actuator. I will look into the possible contact chatter. We also measured the load current. It runs at ~4.5A, with a ~11A inrush on startup.
  8. JSong

    Temperature Limit Switch Failure

    Bill, if you look at this tech spec: https://stevenengineering.com/tech_support/PDFs/31BASW.pdf. It says that it is HP rated. Once the contacts close, the moving contact stops, and the over-travel shouldn't have further impacts. Am I understanding it right?
  9. JSong

    Temperature Limit Switch Failure

    Thanks a lot for replying. You can find all the spec via: http://sensing.honeywell.com/honeywell-sensing-micro-switch-bz-large-basic-product-sheet-004955-5-en.pdf and http://sensing.honeywell.com/nomenclature-micro-switch-bz-ba-bm-be-004970-3-en.pdf The operating range is : -55 °C to 85 °C [-67...
  10. JSong

    Temperature Limit Switch Failure

    Hi all, We had a temperature limit switch failure problem in a heat exchange fan control circuit. The fan is a 1/6 HP single phase motor, and it is controlled by a Honeywell 'BM-2R-A2' temperature limit switch. This limit switch is rated for 1/2 HP that shouldn't have any problem in a 1/6 HP...

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