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Mains frequency

Kelly Marie Angel
Just checked the dynamic demand site and the frequency was down to around49.7 cycles almost down to the lower legal limit never seen that before
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    Kelly Marie:

    Thankfully.my appointment went ok I had loads of tests and saw a consultant who wants me to have an MRI and CT scan and a blood test they are going to give me some stuff to help me stop panicking in the confines of the machine not out of the woods yet but getting there




    Splendid!


    I found an MRI scan of my back (twice) pretty unpleasant. What I couldn't understand was why they didn't put my legs instead of my body in the machine.


    In any event, I just closed my eyes, so it didn't matter whether the magnet was an inch, a foot, or a yard away.

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    Actually, unless you have steel shrapnel inside you, the bigger worry in an MRI scan should not be the magnet whcih is near constant with a small sweep coil adding and subtracting some milliTeslas from it, but the significant fraction of a kW of RF they use to get the nuclear magnets all jiggling together. There is a reason they like the room to be cool.



    Any way, there is no real need to worry - and it sounds like you (both actually) are in good hands.
  • Former Community Member
    0 Former Community Member
    No need to stress over it Kelly, the CT scanner is a quick process but the MRI is indeed confined, so just think of the enormous benefit of the scan revealing your inside workings, so your diagnosis and subsequent care is correct!

    I fell asleep during one of the longer MRI scans as the headphones subdued the noise and yes, it is warm in there!

    Oh, they'll ask about being pregnant and any tattoos! Apparently the very very old or "privately done in your cell" inkings may have contained lead but as non ferrous, I couldn't see the logic as their viewing partition is lead loaded anyway.


    PM me if you need more reassurance.


    Regards


    BOD
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    Simon Barker:




    Denis McMahon:





    Posted by Simon Barker on Feb 14, 2020 8:13 am



    Or build big battery banks around the country.  Spare power from renewables can be stored.  Then when the generations drops too low, the batteries can top the grid up for long enough to bring backup generators on line.




    On a grid system powered by solar power we would certainly lose the stability provided by inertia. However, this is hypothetical, since I cannot envisage such systems. Solar panels are not very clever at night. Also bear in mind that nuclear power, though not strictly renewable, is virtually carbon free and is going to be with us for a good while yet. It is going to be some time before we worry about losing the stability of inertia.

     



     

    Not hypothetical at all.  South Australia already has a huge battery bank, and it appears to be doing a good job. https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/ 


    It isn't intended to run the whole grid for hours on end.  It is there to store enough power to handle any short-term peak load, or sudden losses of supply.

     




     

    By "hypothetical", I meant relying almost totally on solar power. Thanks for the interesting web link, Simon. I have agreed all along that the building of big batteries all over the place makes good sense as we move towards more sources of renewable energy.
  • Former Community Member
    0 Former Community Member

    perspicacious:

    but the MRI is indeed confined, so just think of the enormous benefit of the scan revealing your inside workings, so your diagnosis and subsequent care is correct!

     




     

    Remind me to tell you the story of a junior doctor who used to like to entertain her gentlemen friends in the MRI suite - it took several very well qualified doctors to actually work out what they were looking at when the imaging got onto the NHS network - it then went viral and nearly crashed the network


    OMS
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    I hope it is not related to the "having lead in your pencil" saying OMS?
  • Former Community Member
    0 Former Community Member
    LoL - I couldn't possibly comment


    OMS
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    Could be if the ink is resonant and in the right place! The RF field is several hundred watts of basically microwaves.


    I got my arm quite warm once at 432 MHz, it is an extremely strange feeling......
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    OMS, that sort of thing was done, officially, about 20 years ago in Holland, and got written up in the BMJ among other places

    here - but you need to pay to read more about it  than the webpage.

    For reasons not entirely clear it has far more copy requests than most other BMJ articles about medical imaging.
  • 0
    Well that was heavy reading before breakfast on a Friday morning.

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