[Milsurplus] Brouhaha over Navy ROTHR radar

[Kenneth G. Gordon]

On 30 Mar 2017 at 21:58, Peter Gottlieb wrote:

> I did a lot with lithium ion and now I work with vanadium redox flow batteries.  
> Depending on the system the voltage range will most commonly be in the 400 to 
> 1100 volt DC range.  4 kV strings are being discussed for larger systems but not 
> much so far.  Short circuit on a string is at least 3 kA and on a system can 
> easily be over 100 kA.  When testing we sometimes related a 1 MW fault to a 
> stick of dynamite.  You remember being nearby when it happens.  Most big DC 
> fuses have a max interrupting current of 100 kA and they can explode violently 
> if you exceed that, so yes, the big systems have some challenging protection 
> problems (then there's arc flash).  Oh yes there's design calculations you have 
> to do on busbars because the mutual magnetic field on a fault could break them 
> from their supports.  There are load break contactors to react to less severe 
> problems and the overload "relay" function is programmed into a controller and 
> the current is monitored with current transformers. Also voltage taps so any 
> number of current and voltage vs time parameters can operate that circuit 
> breaker.  So yes a lot of thought goes into over-current and short circuit 
> protection.

All that sounds like very interesting work.

And I repeat: thank you for giving me much more up-to-date information on wind systems, 
etc. I appreciate that very much.

And I would suppose that YOU would care about RFI, since (among other things) you are a 
"radio person", but the manufacturers, in my opinion, will do any and everything they can as 
long as they can to ignore the problem. It is in their best economic interests to do so.

Yes, the Chinese sources of RFI are most often worse than those of "our" manufacturers, but 
ours still are not taking RFI issues seriously enough to "waste" money on a solution.

Again, thank you for the very interesting discussion.

Ken W7EKB

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