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Gr8blu / xnuke, Thank you for your time replying. It is certainly more clear to me now, but I need to fully absorb the depth of what has been said to finally get there. I am always thinking of how to relate topics (any topic) to someone who asks me, and I need to visualize things to be able to...

Hi Hoxton, Thank you for the reply, but to my knowledge these currents do actually exist, and they counter rotate and therefore cut the rotor at 2x fundamental frequency. This causes rapid overheating of the rotor ends (in particular) and eventually ruins the machine. I don't understand the...

Searched the thread archive for this one, but didn't find what I was looking for. After showing someone how to calculate NPS currents from Generator data, they asked my a question that I had never even asked myself, and couldn't answer - What makes NPS currents rotate counter to the rotating...

No argument there, but as there are hundreds of them on this site (and thousands on other sites), and the fact that Manufacturers keep making them, Projects keep installing them, and Standards keep quoting them, then the question still stands. I did nearly have an epiphany though - a sudden...

Follow up: I have come across NETA 2015 Standards stating the following: Sec 7.16.1.1.B.4 Test motor protection devices in accordance with manufacturer’s published data. In the absence of manufacturer’s data, use Section 7.9 and Sec 7.9.1.11 49R Thermal Replica Relay: 1. Determine time delay...

Quick one for the North American audience: Are there any standards (NEMA/NFPA/NEC or other) that specify that thermal overloads need to be current injection tested periodically, and/or after replacement? There are pro's and con's for testing them - pro's are obvious, but the con's are that they...

Thanks waross, Sometimes it doesn't take much for the penny to drop. By reading your opening few lines I suddenly realised where I was going wrong - all phases simply take their positions relative to the grounded point, and not the hull assuming a potential of the phase(s). I take it that my...

I have attached a hand drawing of what I believe are the vectors for an Ungrounded Star, and an ungrounded Delta system, and shown it with a ground fault, on different phases, on the two different voltage systems. Link Please comment on them - good or bad. The first one (Ungrounded STAR)...

Fuse4, Thanks for the reply. I'm not sure that I will be going out to buy the book specially for this, but it does look to be the kind where I could find out the answer. I take it that because you are the only responder (and I appreciate that), the question cannot be readily answered by other...

I am having a bit of trouble getting my head round a problem regarding to systems of varying voltages running in Isolated Earth configuration. It is a floating vessel which comprises of a Topsides earthed system at 13.8kV, and feeders from the Switchboard go to the Marine side (Hull)...

catserveng, Thanks for the postings. Can never have enough good material [bigsmile]

@electricalpete: no you were not fooled by my title. I was indeed after the electromagnetic influences that tend to slow a Rotor down when load current is increased on the Stator of a Generator - that's it. I was not after an explanation on Isoch/Droop or Proportional/Integral control loop...

Gents, Thank you very much for your insights and clear explanations. @electricpete: Very interesting paper you have published there - like you say, the convention is to show (like I simplistically have) Stator coils in the air-gap, and I have actually wondered in the past what effect there is...

I need to roll out an electrical generation presentation to groups of Technicians to help underpin their understanding of generation principals. I was separately discussing with one of them about why Generators tend to slow down when load is applied, and how the Governor is increased to correct...

Waross, I like the alternative way of looking at this very much - thank you very much indeed. I have attached a hand-written pdf file depicting this. Looking at it this way makes me think how simple the original question was to answer (and why didn't I think of doing that...) - just goes to...

And I apologise for maybe being a little sensitive. The analogy I made was just that - analogy. I see that it could be construed as me still not understanding that ways and the means of what is happening despite such valuable input, but I can assure you that is not the case. Thank you for your...

- what on earth are you talking about? Since when have I ever had interaction with you about such things? - is that not what we have been striving to work out? - well I was simply making the analogy of two generation systems running in parallel with one of them forced to operate at a fixed PF...

Thank you rhatcher - that is what I had as well. It has been a good learning exercise for me as I was initially very unsure how to approach combining supplies with differing Power Factors, and making sense of the results. Like I say, thanks to everyone for their inputs - I have already passed...

David, Thank you very much - my figures are now working out and, as near as doesn't matter, matching yours (I used 0.8275 for the load PF). A purple Star for you. Thanks for you help and patience - much appreciated, and thanks to the other responders for their input as well.

David, Thank you for your patience here, and can I ask that you stretch it a bit more... I think I'm having a case of "can't see the wood for the trees". Could you please spell out for me your calculations on how you arrived at a resultant current of 710A when using 0.6684 PF. Nothing I'm...