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  1. bmodrow

    DC High Current Contactors

    General Electric makes High Speed DC Circuit Breakers that will meet your requirements. These are referred to as Gerapid breakers.
  2. bmodrow

    Transformer Oil Analysis -worrisome results

    What are you considering to be a "significant" rise in dissolved gases over that past year and specifically what gases have increased. As stated by others I would resample immediately and verify that the DGA results are the same. If they are not, as stated I would suspect contaiminated samples...
  3. bmodrow

    DC testing voltages

    For acceptance testing refer to the manufacturers recommendation for test voltage which could be as much as 5 times the insulation rating. For normal maintenance of cable that has already been placed in service, I would not recommend testing the cable above its rated value unless you have made...
  4. bmodrow

    Detecting Broken Rotor Bars using Vibration Analysis

    This link may shed some more light on the subject for you. http://www.vibrationschool.com/vibeschool/mans/SpecInter/SpecInter32.htm
  5. bmodrow

    Power Factor Capacitor Failures

    Thank you for the replies thus far. We do have a suitable instrument (Dranetz PP4300) for recording and monitoring. The information I received on the number of air-handelers is not correct either. The information that I now have is that ALL air-handlers run off of this feed and they are all...
  6. bmodrow

    Power Factor Capacitor Failures

    I have little to no expertise in this area and was hoping I could receive some guidance. I have seached the forum regarding PF correction capacitors and have not came up with any solutions. I have a customer that has some power factor correction capacitors across the feed of two air handeling...
  7. bmodrow

    DC Contactors

    One other good supplier of DC contactors is Microelectrica Scientifica located in Italy.
  8. bmodrow

    Testing Small DC Motors

    It is possible to use a meter to check for continuity of the field circuit only. It would also be advisable to megger the field and armature windings to ensure there is no insulation break down. Also inspect brushes and commutator. Keep in mind that if you receive a low megohm reading on the...
  9. bmodrow

    Electric motor RPM vrs Load

    wment horsepower does not equate to motor RPM the change you are making is going to increase system RPM by a factor of two. The main concern you have in determining your pulley sizes is the maximum RPM that the compressor is capable of handling without damaging the compressor. Your drive...
  10. bmodrow

    Watt-Hour/VAR Meter Calibration

    See, I knew it was so simple it was eluding me. My problem stemmed from the fact that I was thinking 0-degrees leading or lagging and not of power factor itself. Thanks for the quick and simple answer jstickley!
  11. bmodrow

    switchgear maintenance

    paulryan1 I think that wbd has given a very good response for starters I would however make the following addition. Inspect bkr contacts, grease, loose hardware, arc chutes (if any) - yearly to 2 I would suggest performing primary injection testing at the same interval you perform your breaker...
  12. bmodrow

    Watt-Hour/VAR Meter Calibration

    A typical calibration for a this type of meter calls for calibration to be performed 1.0 PF(unity), 0.5-lag, and 0.5-lead for watts and this makes perfectly good sense to me. However, for the VAR function the points are 0-lag, 0-lead, .5-lag, .5-lead, .87-lag, and .87-lead. My first question...
  13. bmodrow

    Motor Condition Monitoring

    Have alook at PdMA located onthe web at www.pdma.com The items you want to look at are the Emax and MCE Max testers. I am not familar with Motorstatus or Atesis. We do however use the PdMA equipment in our shop and in the field. Great tools to say the least.
  14. bmodrow

    Resistors in rotor-circuit

    The purpose of the resistors is to control motor speed.
  15. bmodrow

    50hz motor run in 60hz environment

    As stated by acmotorengineer the motor is magnetically identical at 460/60HZ. The cheapest and easiest soultion is to hook directly to your 460 3-phase and test the motor. Is the piece of equipment you are manufacturing being used in the US or Europe? or was a cheaper solution to the...

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