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  1. RAMConsult

    Transformer inrush

    I believe what you meant was that the "..UPS failed to continuously supply power..." For that you need to look at exactly the type of UPS you have, i.e., whether it is on-line, line-interactive, standby, or some combination of the above. Basically if the AC input is directly connected to the...
  2. RAMConsult

    Constant Voltage Transformer Capacitor failing

    The generator adds an additional layer to this. If I understand correctly this is a small (under 10kW) consumer generator that outputs directly to the CVT whose output then goes to a main breaker in a distribution panel. "Normsl" operation is to start the generator and then close the main...
  3. RAMConsult

    Constant Voltage Transformer Capacitor failing

    If something carrying current is discoloring it usually means that it's carrying much more current then it's supposed to. I would get a noncontact thermometer and monitor your bridge pieces for hot spots, it could just be poor crimps. But the real question is why is the current so high, for...
  4. RAMConsult

    Overall Load Analysis

    The word is diversity. OP, you're assuming that every circuit is loaded to the rating of each breaker. It's time to speak to someone with experience doing this type of calculation.
  5. RAMConsult

    4hp single phase motor problem

    It may be that the problem is not electrical but mechanical nature. Assuming for the moment that the centrifugal switch is not at fault it could be a slight misalignment of the pulleys or excess tension in the belt that is causing the bearings to bind enough to create an additional load on the...
  6. RAMConsult

    Phosphor Bronze fastners for transformer terminals

    Phosphor bronze From Wikipedia, the free encyclopedia Phosphor bronze is an alloy of copper with 3.5 to 10% of tin and a significant phosphorus content of up to 1%.... These alloys are notable for their toughness, strength, low coefficient of friction, and fine grain. The phosphorus also...
  7. RAMConsult

    Generator Mod

    Confusing yourself is one thing, killing yourself is quite another. Your problem lies with your combining the "common/ground" connection which are really two separate and distinct functions. In the US the four wires would be red, black, white and green. 240 volts between red and...
  8. RAMConsult

    Motor's Maximum Inertia

    Kelley8, You actually have enough information to solve your problem graphically. Take the motor's speed-torque curve and plot the speed-torque curve of the load on to it. The net difference between the two curves is the torque available for accelerating the load at any given speed. In order to...
  9. RAMConsult

    Flying start on 3phase induction motor

    jb, sorry, the original poster provided enough information by stating 'induction motor trips' and '60 seconds'. Based upon these criteria and the input from other posters, there is no analysis that will support your contention. The main reason that Chapter 11 does not include motors has to...
  10. RAMConsult

    Flying start on 3phase induction motor

    jb, please provide the specific documentation from the Brown Book that says that the voltage will still be high enough to cause damage after 60 seconds as the original poster questioned.
  11. RAMConsult

    Flying start on 3phase induction motor

    It depends upon what your friend defines as massive. As the threads suggested by busbar indicate, there is no problem after an induction motor has been de-energized for more than 10 cycles; however, if the high inertia load has coasted down significantly and is re-energized there will be an...
  12. RAMConsult

    T-8 ballast vs. occupancy sensor

    I would check the sensor circuitry, some are intended for incandescent loads only.
  13. RAMConsult

    Offline generator losses

    You didn't state the rating of the generator or the type of excitation system but in general there are two different operating conditions that need to be examined; i.e., accelerating and steady state. During the acceleration period everything should be de-energised, therefore the only losses...
  14. RAMConsult

    Starting I in induction motor at synchronous speed

    Sorry jb, I commented on the cc's opening question where he posits "If I have an induction motor (500 kW) being driven at exactly synchronous speed,..."; i.e., if this condition were achieved what would be the result. Furthermore, at your prodding, cc clarified that his setup was...
  15. RAMConsult

    Starting I in induction motor at synchronous speed

    cc, the reason the starting current is so low at exactly synchronous speed is that the line is only supplying the initial inrush and steady-state magnetizing current plus copper losses while the small drive motor is supplying all the power that is required to overcome the inertia plus friction...
  16. RAMConsult

    corona factor F

    The clue here is that 'F' is determined by test; i.e., it is a function of multiple factors which can vary widely and whose combinations are too varied to determine a typical value. Some of these factors include conductor: material; construction; number, pitch, and diameter of strands...
  17. RAMConsult

    24 kA A.C. Source?

    Achieving these short circuit currents in a safe manner is a non-trivial task; therefore I suggest you check the following links to see how others do it: http://powersearch.cpri.res.in/LABS/sc.htm http://powersearch.cpri.res.in/stds/1500mva.htm...
  18. RAMConsult

    Loop inductance on DC Overhead line system

    Try googling on "dc traction system calculations", you should get about 6,770 hits, the answer to your question is in there somewhere.
  19. RAMConsult

    Looking for RJ45 physical switch.

    Try www.kristamicro.com they sell a wide variety of switch boxes. I've also gotten lucky at computer or ham radio shows in my area.
  20. RAMConsult

    Recommendation for microwave occupancy sensor

    Try this link to a robotics site: http://massmind.org/techref/robotics.htm

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