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  1. SparkOmatix

    Low Voltage MCC - Build/Configuration Tool

    Does anyone know what manufacturers (Eaton, ABB, Schneider, Allen Bradley, Siemens, etc.) offer either a cloud/web-based tool or [free] downloadable software that will allow me to build out a motor control center with known loads and provide me a layout visualization? Ideally something that is...
  2. SparkOmatix

    Power One-Line Requirement?

    We have many remote, unmanned, compressor sites. The voltages from from 3Ph 480V to 240/120 (most are single phase 240/120). Are One-Lines required by some governing body (OSHA perhaps?)? Is there anything in NFPA XXX stating one "shall" be required to have such an animal? If so, is there...
  3. SparkOmatix

    System Grounding Question

    We have a compressor/meter-station site where we have grounded everything together via copper wire underground and grounding rods. There is one portion (meter skid) where they will install isolation kits at the incoming and outgoing flanges...ultimately isolating this portion from everything...
  4. SparkOmatix

    A question regarding "Free Air"

    I have a question for regarding the definition of "Free Air". I have attached a photo of an older installation. You will three (3) large disconnects. Inside each disconnect is an old Klockner Moeller 800AF/AT Breaker. On the line side of each breaker lands two (2) sets of 3-1/C 500MCM...
  5. SparkOmatix

    Effects of reduced/low frequency (VFD) on a motor

    I know the effects of increasing the frequency (above 60 Hz) essentially shortens a motors life (heating, etc.). I wish to know what, if any, detrimental effects occur from running a motor at a lower frequency…say 40 Hz, for a majority of the time.
  6. SparkOmatix

    Sizing a Circuit Breaker

    What is the proper way to size a circuit breaker? I have a squirrel cage motor with "X" full load amps. Does code say you will protect motors of this type...and perhaps between a certain horsepower...with a Circuit Breaker rated at "Y%" of the FLA? Thanks.
  7. SparkOmatix

    Replacing a 40HP Motor with a 50HP Motor

    DPC, By the way...thanks for taking the time offer up your thoughts and share your knowledge.
  8. SparkOmatix

    Replacing a 40HP Motor with a 50HP Motor

    You state "Conductor must be rated at least for 81 A. That will require #3 AWG (copper), minimum." Looking in the 2011 Code Book, Article 310, Table 310.15(B)(16) I see that a #4 at 75C is good for 85A; therefore, replacing the #4 with #3 would not be required, no? Also, is it 125% of FLA...
  9. SparkOmatix

    Replacing a 40HP Motor with a 50HP Motor

    I have an Allen Bradley Size 3 Starter with a maximum HP rating of 50 HP, an overload block adjustable to 75 Amps, a 3P 100 Amp Breaker, and (3) #4 THHN Wires. The Compressor motor is approximately 200 linear feet from the MCC panel. This is the current configuation on a 40HP motor. I am...
  10. SparkOmatix

    GE Multilin 750 - "Ground Time Overcurrent"

    The 5000kVA transformer (located between the 15kV gear and the 5kV gear)is High-Resistance Grounded. The Ground Overcurrent is indeed using a seperate CT (50/5).
  11. SparkOmatix

    GE Multilin 750 - "Ground Time Overcurrent"

    This is not a new installation, no. I am not aware of any recent changes. These two are not typically run simultaneously but have been successfully run simultaneously before. I'm looking into what changes have been made since such occurred. I will also look to find the current/angles at time...
  12. SparkOmatix

    GE Multilin 750 - "Ground Time Overcurrent"

    I have a switchgear (15kV, 95kV BIL, 1200A) that feeds a 5000kVA, 15kV to 4160V transformer that in turn powers a 5kV switchgear (1200A, 60kA RMS symmetrical). The 5kV switchgear feeds to 1750HP motors. When we attempt to start one while the other is running...it runs for about 5 minutes then...
  13. SparkOmatix

    480/277 Y Secondary 4-Wire Service Question

    I mistakenly put "400" when it is indeed 500. There are parallel feeds coming off the xfmr. They feed 3 independent starter racks (think guttered bus). Each rack is fused with 1200A time delay fuses(LTL-1200). Note, there are no 277V loads.
  14. SparkOmatix

    480/277 Y Secondary 4-Wire Service Question

    I have a question or two that I hope someone can aid in answering. I have a 2500kVA transformer with the secondary (480/277 Y) feeding a bus with the following 4-wire configuration: 3-400 KCMILL/ phase, 3-4/O neutrals (X0), and 3-#2 equipment grounds. Question 1: what happens if one of the...
  15. SparkOmatix

    Class I Div II Area and 24VDC

    I have an IS 24VDC transmitter located in a Class I Div II area. It goes back to a NEMA 4 junction box some 10' away. There is a 24VDC terminal strip in said box - nothing more nothing less. The conduits entering/leaving box have seal-offs poured. There is also a seal-off at the device. I...
  16. SparkOmatix

    Going from PVC (concrete ductbank) to RMC (stubups/aboveground) Part 2

    My initial post was as follows: A concrete, below-ground, ductbank system made up of PVC conduit. At every point of stub-up, a transition from PVC to RMC is performed. The RMC will have a grounding bushing on it and it will be connected to the system ground grid. Is this an acceptable...
  17. SparkOmatix

    Going from PVC (concrete ductbank) to RMC (stubups/aboveground)

    Hi David. Let me begin by saying "thank you." Yes, by RMC I mean rigid metal conduit. Yes, all circuits will have a ground wire. Thanks for the recommendation regarding corrosion. It is duly noted.
  18. SparkOmatix

    Going from PVC (concrete ductbank) to RMC (stubups/aboveground)

    Is the following permissable: A concrete, below-ground, ductbank system made up of PVC conduit. At every point of stub-up, a transition from PVC to RMC is performed. The RMC will have a grounding bushing on it and it will be connected to the system ground grid. Is this an acceptable...
  19. SparkOmatix

    CAT Generator Current Unbalance Question

    I thank you all for your time and effort in commenting on my post. All of you have provided great insight!
  20. SparkOmatix

    CAT Generator Current Unbalance Question

    During testing CAT noticed a small load unbalance on our generator and I wanted to get thoughts on this. The CAT technician seemed to think it might cause premature wear on the generator eventually. They said typically they did not get too concerned unless the imbalance was over one hundred...

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