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  1. BigMotorGuy

    690v 3 phase application lead wire rating

    TBE, in regard to the peak voltage versus RMS, wiring ratings are RMS values, so I don;t believe that is an issue. Waross, if each individual wire is rate at 600v between the inner conductor and (in this case) the out SST armor (i.e. ground), then having 2 cables next to each other (i.e. the...
  2. BigMotorGuy

    690v 3 phase application lead wire rating

    Stupid question, but I have an application going into a 690v 3 phase system, so since the actual voltage to ground on any of the 3 legs is 690/sqrt3 = 398.4v using 600v rate wire is ok right?
  3. BigMotorGuy

    NEC 500 Class I/Div I Purged Junction Box Requirements

    To All, correction, the boxes are actually cast Div I boxes, but that assumes you use a rated gland which we do not at this point. The area is a Div I since it is in the immediate area for a submerged LNG pump electrical feedthru. I guess the easiest answer would be to seal the cable with a...
  4. BigMotorGuy

    NEC 500 Class I/Div I Purged Junction Box Requirements

    We run a test stand that is rated Class I/Div I hazardous area in which we run multiple electric pumps from low voltage up to 6600v. Since we install and tear down the pump connection setup on a daily basis (hence the test stand designation), we do not have the luxury of having sealed AEx e...
  5. BigMotorGuy

    R134a Refrigerant Corrosion

    Looking for material compatibility of typical induction motor components when exposed/submerged in R134a refrigerant, specifically ixlpe lead wire insulation and epoxy resins.
  6. BigMotorGuy

    Junction Box Ratings versus minimum wire size?

    Thanks for the comments Warros. I get what you are saying about the physical fit, but that is not the problem. the problem is an inspector is having a problem with the wire being smaller than the minimum size noted on the box. We use hazardous area glands sized appropriately for the present...
  7. BigMotorGuy

    Junction Box Ratings versus minimum wire size?

    I have a given junction box that has a current rating above the rating of the load (induction motor). The box stated a minimum wire size which ties into the box current rating. Since the load is much lower than the box rating (e.g. 250 amp box rating for a 100 amp FLA motor rating), do I still...
  8. BigMotorGuy

    Easiest way to provide constant 250 ARMS for junction box thermal testing?

    Thanks for all the help. I think I will look at renting a unit per ScottyUK and see what I can get for cheap. this is a one off thing for me, so buying equipment is not in the budget! I do like the CT suggestion though....I will see what our test guys have and maybe do a scaled down test to...
  9. BigMotorGuy

    Easiest way to provide constant 250 ARMS for junction box thermal testing?

    I am looking for the best/easiest way to perform a temperature rise test (i.e. measure box temperature with 250amps flowing through the 3 phases - need a T6 rating) on a new junction box which is rated at 6.6kv and 250amps. Will simply finding a constant current power supply rated to 250amps or...
  10. BigMotorGuy

    Phase Rotation Check - 3.3kv Submerged Generator

    Thanks for all the info.....I cannot spin the rotor by hand, but can drive it at about 10Hz with our hydraulic drive pump (runs off of a VFD), so using a o-scope, I assume I will still be able to verify whether 120 degree or 240 degree separation between the phases on the motor leads.
  11. BigMotorGuy

    Phase Rotation Check - 3.3kv Submerged Generator

    Oldfieldguy, Thanks for the procedure......question, I assume when you say "with the generator running" you mean the generator being driven mechanically and with the power leads opened? Also, do you only need to take one measurement between any 2 phases or must you measure 3 times between each...
  12. BigMotorGuy

    Phase Rotation Check - 3.3kv Submerged Generator

    I have a need to verify phase rotation on a submerged expander generator. We are in testing phase and need to verify the correct rotation prior to trying to synch with the power grid. This is a 2MW induction generator (2 pole) and we do not have access to the unit as it is submerged in LNG...
  13. BigMotorGuy

    IEC 61000-6-4 EMC Testing for 3 Phase Induction Motors?

    Do 3 phase squirrel cage induction motors (550Hp, 3.3kv, 50Hz) produce EMI which may be problematic for IEC 61000-6-4? Do different neutral grounding systems (i.e. ungrounded, grounded, resistance grounded, etc.) have any affect on this? I believe this standard references a frequency range...
  14. BigMotorGuy

    Bondable Magnet Wire Insulation Removal

    The easiest way is to burn the coating off with a hand lighter, then clean with isopropyl alcohol. This will leave you with a clean copper wire end to make connections with.
  15. BigMotorGuy

    Induction Motor or Generator EMC/EMI Testing?

    Skoggsgura.........good info in the presentation. KllrWolf, I tend to agree that a standard 3 phase DOL induction machine will not generate any EMI except maybe right at the grid frequency. I have had some experience with small universal motors and due to the brush commutation, you would get...
  16. BigMotorGuy

    Induction Motor or Generator EMC/EMI Testing?

    Do DOL induction machines in general generate EMI levels which need to be considered? Does NEMA or IEEE address induction machines in regard to electrical noise? I realize that if they are VFD driven, this can be an issue due to the drive itself, but wondering if DOL applications need to be...
  17. BigMotorGuy

    Synchronous Reactance for Induction Motors?

    Is the synchronous reactance a parameter for asynchronous induction motors or does it only apply to synchronous machines? If so, how does one calculate it from typical equivalent circuit info? Also, how does one determine the transient time constant on an induction motor in the event of a...
  18. BigMotorGuy

    Epoxy VPI System Vacuum Levels

    Thanks Motorwinder........that was my thoughts as well. We currently double dip all of our motors and with our spec of 3 Torr, our pump has trouble maintaining it at times. Though I think we do need a rebuild on the pump, I was considering going to a higher capacity vacuum pump that is capable...
  19. BigMotorGuy

    Epoxy VPI System Vacuum Levels

    In regard to form wound induction motors, are there any drawbacks to drawing a higher than recommended vacuum(recommended by the VPI equipment manufacturer)? For example a recommended vacuum level of 3 torr is typical for using epoxy resin. Is going to less than 1 Torr going to cause any...
  20. BigMotorGuy

    PI Test Values AC Induction Motors: Random Wound Versus Form Wound Ratios

    Thanks for the feedback! It makes sense that the meter capabilities limits the ability to capture the increasing resistance profile, especially if the test only looks at the 1 minute and 10 minute mark. It would seem like a good idea to develop a test and equipment which can record data...

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