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  1. PwrCntEE

    Paralleling 2-cycle and 4-cycle diesel eng gen sets

    I do not have much hands-on with generators, but have reviewed some layouts. With proper monitoring, protection, and syncing before allowing them to close together, as with any multiple source system. I do not see a problem with engine type.
  2. PwrCntEE

    Change motor speed for vacuum control?

    I agree that you should get a mechanical opinion. I will offer my thoughts, just thinking aloud. Depending upon the amount of range you need and the min/max targets will most likely determine the easy/cost effective way (not that one is much more dificult than the other). My experiance with...
  3. PwrCntEE

    Style of PE stamp

    I just received notice of passing the PE exam and I now need to get my seal. Everyone in the office uses stamp and pad. However, I think I would preferr a self-inking stamp. My only concern is do they hold up to the use of a PE. Does anyone have experiance with the self-inking that might...
  4. PwrCntEE

    calculating single phase fault

    Thank you, I use the point-to-point method and many times forget about the P.U. method. The underlying question was posed by a co-worker. He is trying to model (enter) a 3ph, 12.5kV system in EDSA (software package). However, it must have balanced loading. While it will calculate 1ph and...
  5. PwrCntEE

    calculating single phase fault

    I'm trying to reflect a fault level through a single phase transformer winding. I know I can use the %Z and the rated current to get the maximum unlimited secondary fault current. But If I know the actual level on the primary, how do I relect it thru to the secondary? I cannot just use the...
  6. PwrCntEE

    Finding complex impedance of AC unit...

    NEC 2002, 440.2 definitions may help
  7. PwrCntEE

    Phase angles on DYN11 transformers

    A client had one of the tranformer fault and needed rebuilt. They got the rebuilt tranformer back and put it back in service. We were installing a tie switch between this and another transformers. As part of commissioning, we noticed a similar problem. As a last resort, since it was just...
  8. PwrCntEE

    Receptacle Limits on a brach circuit per NEC

    Sorry, I miss stated. I have the handbook which has an exhibit 220.4 just below 220.3(B)(9). I don't think the code puts a limit in writing (as stated above); hence, when I saw the example in the handbook, I saw another interprutation.
  9. PwrCntEE

    Receptacle Limits on a brach circuit per NEC

    Hit the nail on the head.....Thanks!
  10. PwrCntEE

    Receptacle Limits on a brach circuit per NEC

    I am missing something in the NEC. #220.3.B.9 states that for a 20A circuit they allow 13 receptacles. This is only if they allow the breaker to be loaded 100%. I thought I had to size the breaker to 125% of the load or limit the load to 80% of the breaker. By this method, the limit is 10...
  11. PwrCntEE

    Transformer specs/ detailing

    I'm not sure what you are looking for, but you might start with the vendor of your transformer. Otherwise, transformers are really standardized for wiring arrangements, try GE at www.geindustrial.com. If your looking for drafting symbols, you might also try the AIA website.
  12. PwrCntEE

    Control Transformer Grounding in Washdown areas

    Interrupter: I hope I am misunderstanding you. Do you mean that you do not ground the transformer so that if you do have a fault, you size the insulation rating to handle the fault and not arc? If so, this is only acceptable if you have a Impendance Grounding System installed. Otherwise...
  13. PwrCntEE

    Utility Impedance & Isc

    Call your utility and they will give you their system caculations for the specific data at your location. Be sure to push them, because they will often give you some data but not all. Typically, they do not want to give you an X/R ratio of their system cause it can/will change in the future...
  14. PwrCntEE

    If I know Hz input of a motor, how do I know RPM?

    You need to know more information: motor type and number of poles, etc. Assuming you are talking an induction motor, Syncronous RPM = (120 * Frequency) / (# of Poles) 120 is a constant example: RPM = 120 * 60 / 4 = 1800 RPM
  15. PwrCntEE

    Control Transformer Grounding in Washdown areas

    The purpose for the ground connection is to create a path of least resistance to protect anyone who comes in contact during a failure. Not installing the ground will, without question, increase risk to personnel. Not to mention it is an obvious code violaiton to not ground.

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