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Recent content by jktwn

  1. jktwn

    Transmission Line Cost

    thanks FPelec. Will be designed for NESC Hheavy.
  2. jktwn

    Transmission Line Cost

    I'm needing a good rough estimate of the cost per mile to build a 50 mile 138KV, 1272 ACSR transmission line in the central US excluding land acqusition cost? Route is straight, land is flat, mostly open range and sparsly populated. Considering wooden H-frame or concrete structures. Sorry, I...
  3. jktwn

    Harmonic Solution Idea

    Problem is on the distribution (12.5KV) lines. All of the individual 480V vfds are working together to corrupt the grid PQ. Any new drives added automatically are subjected to the harmonics.
  4. jktwn

    Harmonic Solution Idea

    We are having problems in the field with drive trips, fuses blowing,etc caused by high level 5th order harmonics on our lines. With over 1000 6 pulse vfds installed and little or no filtering on the drives, the voltage distortion is really bad. The thought is to have half of the sites pole top...
  5. jktwn

    GE 1000 HP DC Motor Field Coil Rewind

    Good feedback. Looks like the motor is down for the count. We do have another 1000HP GE motor at another site in USA that is available but I'm not certain if it will fit. It is a frame size CD6270 versus CD6766 that came out. Electrical specs are similar althoght rpm is 1600 versus 1200. Does...
  6. jktwn

    GE 1000 HP DC Motor Field Coil Rewind

    A couple of days ago we had a failure of a GE 1000 hp extruder motor on one of our films lines here in our plant. The motor had a lot of water and ice ingested into the air intake from the roof during the snow storm shorting out 2 of the 6 motor field windings. The motor shop says the repairs...
  7. jktwn

    Looking for Flender Cavex Gearbox

    We had a driveshaft failure that bent the worm shaft on a Flender Cavex CFW 250 gear reducer ratio 16.67:1. We have ordered a gearbox from Flender but it won't ship until mid-December. Anyone have an idea where to look for an emergency replacement gearbox maybe on the surplus market...
  8. jktwn

    Unknown Thermistor in GE 600 HP DC Motor

    sed2developer, The Siemens drive is a model 6RA7091. Talked with our in-house technical person and he found the relavent parameters for this drive to configure it for a PTC 600 ohm thermistor. We popped the peckerhead on the motor and found that the 3 thermistors in the motor are wired in...
  9. jktwn

    Unknown Thermistor in GE 600 HP DC Motor

    According to GE it is a PTC with R=600 Ohms.
  10. jktwn

    Unknown Thermistor in GE 600 HP DC Motor

    We recently had a GE 600HP DC motor suffer overheating and destruction when the cooling air intake became blocked by debris. During the the investigation it was discovered that the motor overtemperature devices (thermistor - GE p/n 36A172828BBG01) were not configured to work with the Siemens...
  11. jktwn

    Carbon Brush Wear Alarm Circuit

    Thanks UKpete & stardelta for the suggestions. After considering your thoughts on the matter and visiting with the brush rep (he too warns about relying on wear sensors even though they sell them), I have decided to drop the alarm circuit project at least for now. The brush munufacturer makes...
  12. jktwn

    Carbon Brush Wear Alarm Circuit

    I'm looking at adding BW detection and alarm to dc motors ranging in size from 2HP to 1000HP. We are currently measuring and recording brush lengths at each PM turnaround and will be generating statistics on wear rates. I would like to install one sensored brush in each motor if possible and...
  13. jktwn

    DC Motor flashover

    Ref thread 237-32685
  14. jktwn

    Carbon Brush Wear Alarm Circuit

    I am researching methods to retrofit a bunch of dc motors in the plant with indicator lights to let someone know when its time to replace brushes in the motor. I see where one of the brush manufacturers has come out with an embedded sensor in their brushes that can be used to signal an...
  15. jktwn

    PFC Cap Bank Repair vs Replace Economics

    Wareagle, Overall demand is just above 20MVA and we operate 24/7. Our demand is close to flat which makes our utility company happy. Keewee, I wasn't involved in the decision, but back then we had a very capable retired power company consultant in the plant and his recommendations were acted on...

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