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29th July 2014, 02:00 PM #31GOLD MEMBER
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Interesting thread Grahame. Just as an aside to this I have been having no end of trouble with my whoflungdung (OKAI) plasma cutter and each time i take it back to where i bought it they cannot fault it. Take it home and the overtemp light comes on and it wont start a cut. Thought it may be overvoltage, borrowed a certified meter from work, 249 volts, i am near the distribution transformer, so could be the problem. Take it back to the shop, get it working and measure the volts there, 247, so not a voltage problem. Finally give it a try at home again, fails, turn off the AC switch on the meterbox from the inverter, and hey presto it works OK and cuts and cuts some more. Seems the harmonics created by the inverter travelling down the submains to the shed upset the electronics in the plasma cutter and trigger the overtemp circuit.
Something for you to consider with your plans.
rgds,
Crocy.
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29th July 2014, 03:11 PM #32Cba
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- Aug 2007
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One problem is that people want highly efficient inverters, which calls for high chopper frequencies and fast switching times which produce interference noise.
Another problem is that people want cheap solar systems. So makers may be tempted to leave the EMI filter off the inverter and save on a shielded metal enclosure, and installers save on external RFI filters and twisted DC cables and the ferrite cores that should go over wires. If you want to be sure, check that the inverter of your choice explicitly meets the current EMI standards for Interference (not the ones from 10 years ago). And ask the installer what he is doing (if anything) to minimize interference from the DC side of the inverter.
PS: if you are after the cheapest possible quote, maybe better do not ask about interference.
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29th July 2014, 03:56 PM #33
Crocy,
Does this mean you will have to plasma cut on mains power when the sun goes down?
Its certainly one for the electrical ginger beers and a question I shall put to my installer.
PDW
I have specified best quality components all the way through.While I do not expect problems with a top line system, it is a question worthwhile asking.
Notwithstanding I shall put the question to the installer about the EMI shielding standards being current, Bugger ! I already have enough trouble with sunspot interference on my workshop radio without any more problems arising .
Thought seriously It does raise some concerns as my Fronios Magicwave is chocka block full of electron trickery, though I half suspect that Fronios being one of the early and top shelf developers of PV inverters may be on to that one already. It certainly is a whole new can of worms.
Grahame
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29th July 2014, 08:59 PM #34GOLD MEMBER
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- Jun 2005
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