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  1. mparenteau

    UPS Load Test

    It's more typical to use resistive load banks. I suppose you could use a reactive load bank...I personally have never seen it done. Mike
  2. mparenteau

    Areas of New Jersey that still use ungrounded delta?

    perhaps this will help: https://www.eng-tips.com/threads/california-utilities-preference-for-ungrounded-distribution.475516/ Mike
  3. mparenteau

    VFD increasing the motor winding temperature

    Distance from drive to motor? Is the motor inverter duty rated? Mike
  4. mparenteau

    new ATS and now one downstream Breaker tripping

    Sounds like an inrush trip. Is your breaker feeding the transformer set properly? Mike
  5. mparenteau

    Gas group IIA vs IIB, IIC

    You'll have to do your due diligence and check the frame sizes with the corresponding motor group. Also, be careful with AIT and any VFD applications as it pertains to motor inverter duty capability. Mike PS for example, you may have a motor spec that gives a T3C temperature code for a sine...
  6. mparenteau

    Tie Breaker in Series and Bus duct

    Not sure about your voltage...maybe a tie-breaker in your busduct link? Mike
  7. mparenteau

    Reactance and Time constant tests for a generator

    Programs like SKM, ETAP, etc.
  8. mparenteau

    Reactance and Time constant tests for a generator

    That information certainly helps to model your capability curve. Mike
  9. mparenteau

    What is positive to negative sequence coupling and negative to positive sequence coupling ?

    Mutual coupling... Mike
  10. mparenteau

    Analysis for determining location of arrestors on overhead distribution lines

    Maybe this will help: IEEE Std C62.22TM-2009 Mike PS Found this paper as well: https://www.sciencedirect.com/science/article/pii/S0378779621005642#:~:text=Line%20surge%20arresters%20are%20installed,to%20a%20poor%20soil%20conductivity.
  11. mparenteau

    Arc Flash in SKM

    Assuming you have a MV or HV circuit breaker w/ no "brains", the relay is the brains. So, there will be a slight delay between relay sensing, and the relay issuing a trip command. So it would actually be longer than 2 sec, unless you included the opening time of the breaker. Mike
  12. mparenteau

    MV Switchgear Fuse

    Who knows? Did you look at how the fuse performs at 12x @ .1 sec and 20x @ .01 sec (I have seen 25x @ .01 sec as well)? Mike
  13. mparenteau

    Single VFD running two motors - One motor temperature much hotter.

    An ID run is a procedure whereby the VFD "learns" the motor(s) characteristics via an algorithm. I'll defer to jraef on the rest... Mike
  14. mparenteau

    Running a DOL starter from a VFD

    There are usually interlocks between a VFD, load side disconnect and the VFD itself (I've never used a starter on the load side of a VFD, but have installed disconnects on the load side of a VFD for local isolation). Drives don't like switching actions on the load side of their terminals while a...
  15. mparenteau

    Eutectic Alloy vs E100 Solid State Overload

    Solid state OLs will give you some flexibility on setting based on FLA. Some have phase loss settings for motor protection as well. Mike
  16. mparenteau

    480V ungrounded Delta

    Thanks to dpc for clarifying. Yes...400A resistor on a 480V system is no bueno. My suggestion is for a MV system.
  17. mparenteau

    480V ungrounded Delta

    Consider the withstand time of the resistor. A 400A resistor is pretty common, having a 10 second withstand. Extended time ratings means more $$$. Mike
  18. mparenteau

    Current clamp meter high voltage

    I use this: https://www.mitchellinstrument.com/hd-electric-hva-2000-high-voltage-digital-ammeter-up-to-500kv.html?gad_source=1&gclid=EAIaIQobChMI5ZvQ8uesigMVuiytBh3zcxGFEAQYASABEgJz0fD_BwE Mike
  19. mparenteau

    3-Phase Faults Vs Line to ground

    I would just add to dpc's commentary: close-coupled switchgear, i.e. perhaps a power style transformer that is a few feet away from a switchgear lineup, will likely have a SLG fault current (3*Io) greater than the 3PH fault current. As dpc addresses above, this is cause for concern. Mike
  20. mparenteau

    Industrial System Harmonics Application

    Right or wrong...I used the following: <5% VTHD <33% ITHD Anything above those #'s, I would look into filtering if operational/equipment issues were noticed, etc. I hadn't experienced any operational down-sides to those #'s, but your mileage may vary depending on your installation. Mike

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